Java Persistence API, Version 2.1

Java Persistence API, Version 2.1
JSR 338: JavaTM Persistence API, Version 2.1
Java Persistence 2.1 Expert Group
Specification Lead:
Linda DeMichiel, Oracle
See http://jpa-spec.java.net to comment on and discuss this specification
F
Version 2.1, Final Release
R
l
a
n
i
e
s
a
e
l
e
April 2, 2013
Java Persistence 2.1, Final Release
Oracle
Specification: JSR-000338 Java(tm) Persistence Specification ("Specification")
Version: 2.1
Status: Final Release
Specification Lead: Oracle America, Inc. (“Specification Lead”)
Release: 2 April 2013
Copyright 2013 Oracle America, Inc.
All rights reserved.
LIMITED LICENSE GRANTS
1. License for Evaluation Purposes. Specification Lead hereby grants you a fully-paid, non-exclusive,
non-transferable, worldwide, limited license (without the right to sublicense), under Specification Lead's
applicable intellectual property rights to view, download, use and reproduce the Specification only for
the purpose of internal evaluation. This includes (i) developing applications intended to run on an implementation of the Specification, provided that such applications do not themselves implement any portion(s) of the Specification, and (ii) discussing the Specification with any third party; and (iii) excerpting
brief portions of the Specification in oral or written communications which discuss the Specification provided that such excerpts do not in the aggregate constitute a significant portion of the Specification.
2. License for the Distribution of Compliant Implementations. Specification Lead also grants you a perpetual, non-exclusive, non-transferable, worldwide, fully paid-up, royalty free, limited license (without
the right to sublicense) under any applicable copyrights or, subject to the provisions of subsection 4 below, patent rights it may have covering the Specification to create and/or distribute an Independent Implementation of the Specification that: (a) fully implements the Specification including all its required
interfaces and functionality; (b) does not modify, subset, superset or otherwise extend the Licensor Name
Space, or include any public or protected packages, classes, Java interfaces, fields or methods within the
Licensor Name Space other than those required/authorized by the Specification or Specifications being
implemented; and (c) passes the Technology Compatibility Kit (including satisfying the requirements of
the applicable TCK Users Guide) for such Specification ("Compliant Implementation"). In addition, the
foregoing license is expressly conditioned on your not acting outside its scope. No license is granted
hereunder for any other purpose (including, for example, modifying the Specification, other than to the
extent of your fair use rights, or distributing the Specification to third parties). Also, no right, title, or
interest in or to any trademarks, service marks, or trade names of Specification Lead or Specification
Lead's licensors is granted hereunder. Java, and Java-related logos, marks and names are trademarks or
registered trademarks of Oracle America, Inc. in the U.S. and other countries.
3. Pass-through Conditions. You need not include limitations (a)-(c) from the previous paragraph or any
other particular "pass through" requirements in any license You grant concerning the use of your Independent Implementation or products derived from it. However, except with respect to Independent Implementations (and products derived from them) that satisfy limitations (a)-(c) from the previous
paragraph, You may neither: (a) grant or otherwise pass through to your licensees any licenses under
Specification Lead's applicable intellectual property rights; nor (b) authorize your licensees to make any
claims concerning their implementation's compliance with the Specification in question.
4. Reciprocity Concerning Patent Licenses.
a. With respect to any patent claims covered by the license granted under subparagraph 2 above that
would be infringed by all technically feasible implementations of the Specification, such license is conditioned upon your offering on fair, reasonable and non-discriminatory terms, to any party seeking it
from You, a perpetual, non-exclusive, non-transferable, worldwide license under Your patent rights
2
4/2/13
Java Persistence 2.1, Final Release
Oracle
which are or would be infringed by all technically feasible implementations of the Specification to develop, distribute and use a Compliant Implementation.
b With respect to any patent claims owned by Specification Lead and covered by the license granted
under subparagraph 2, whether or not their infringement can be avoided in a technically feasible manner
when implementing the Specification, such license shall terminate with respect to such claims if You initiate a claim against Specification Lead that it has, in the course of performing its responsibilities as the
Specification Lead, induced any other entity to infringe Your patent rights.
c Also with respect to any patent claims owned by Specification Lead and covered by the license granted
under subparagraph 2 above, where the infringement of such claims can be avoided in a technically feasible manner when implementing the Specification such license, with respect to such claims, shall terminate if You initiate a claim against Specification Lead that its making, having made, using, offering to
sell, selling or importing a Compliant Implementation infringes Your patent rights.
5. Definitions. For the purposes of this Agreement: "Independent Implementation" shall mean an implementation of the Specification that neither derives from any of Specification Lead's source code or binary code materials nor, except with an appropriate and separate license from Specification Lead,
includes any of Specification Lead's source code or binary code materials; "Licensor Name Space" shall
mean the public class or interface declarations whose names begin with "java", "javax", "com.sun" and
“com.oracle” or their equivalents in any subsequent naming convention adopted by Oracle America, Inc.
through the Java Community Process, or any recognized successors or replacements thereof; and "Technology Compatibility Kit" or "TCK" shall mean the test suite and accompanying TCK User's Guide provided by Specification Lead which corresponds to the Specification and that was available either (i) from
Specification Lead's 120 days before the first release of Your Independent Implementation that allows
its use for commercial purposes, or (ii) more recently than 120 days from such release but against which
You elect to test Your implementation of the Specification.
This Agreement will terminate immediately without notice from Specification Lead if you breach the
Agreement or act outside the scope of the licenses granted above.
DISCLAIMER OF WARRANTIES
THE SPECIFICATION IS PROVIDED "AS IS". SPECIFICATION LEAD MAKES NO REPRESENTATIONS OR WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO, WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE,
NON-INFRINGEMENT (INCLUDING AS A CONSEQUENCE OF ANY PRACTICE OR IMPLEMENTATION OF THE SPECIFICATION), OR THAT THE CONTENTS OF THE SPECIFICATION
ARE SUITABLE FOR ANY PURPOSE. This document does not represent any commitment to release
or implement any portion of the Specification in any product. In addition, the Specification could include
technical inaccuracies or typographical errors.
LIMITATION OF LIABILITY
TO THE EXTENT NOT PROHIBITED BY LAW, IN NO EVENT WILL SPECIFICATION LEAD OR
ITS LICENSORS BE LIABLE FOR ANY DAMAGES, INCLUDING WITHOUT LIMITATION,
LOST REVENUE, PROFITS OR DATA, OR FOR SPECIAL, INDIRECT, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF OR RELATED IN ANY WAY TO YOUR HAVING,
IMPELEMENTING OR OTHERWISE USING USING THE SPECIFICATION, EVEN IF SPECIFI-
3
4/2/13
Java Persistence 2.1, Final Release
Oracle
CATION LEAD AND/OR ITS LICENSORS HAVE BEEN ADVISED OF THE POSSIBILITY OF
SUCH DAMAGES.
You will indemnify, hold harmless, and defend Specification Lead and its licensors from any claims arising or resulting from: (i) your use of the Specification; (ii) the use or distribution of your Java application,
applet and/or implementation; and/or (iii) any claims that later versions or releases of any Specification
furnished to you are incompatible with the Specification provided to you under this license.
RESTRICTED RIGHTS LEGEND
U.S. Government: If this Specification is being acquired by or on behalf of the U.S. Government or by a
U.S. Government prime contractor or subcontractor (at any tier), then the Government's rights in the
Software and accompanying documentation shall be only as set forth in this license; this is in accordance
with 48 C.F.R. 227.7201 through 227.7202-4 (for Department of Defense (DoD) acquisitions) and with
48 C.F.R. 2.101 and 12.212 (for non-DoD acquisitions).
REPORT
If you provide Specification Lead with any comments or suggestions concerning the Specification
("Feedback"), you hereby: (i) agree that such Feedback is provided on a non-proprietary and non-confidential basis, and (ii) grant Specification Lead a perpetual, non-exclusive, worldwide, fully paid-up, irrevocable license, with the right to sublicense through multiple levels of sublicensees, to incorporate,
disclose, and use without limitation the Feedback for any purpose.
GENERAL TERMS
Any action related to this Agreement will be governed by California law and controlling U.S. federal law.
The U.N. Convention for the International Sale of Goods and the choice of law rules of any jurisdiction
will not apply.
The Specification is subject to U.S. export control laws and may be subject to export or import regulations in other countries. Licensee agrees to comply strictly with all such laws and regulations and acknowledges that it has the responsibility to obtain such licenses to export, re-export or import as may be
required after delivery to Licensee.
This Agreement is the parties' entire agreement relating to its subject matter. It supersedes all prior or
contemporaneous oral or written communications, proposals, conditions, representations and warranties
and prevails over any conflicting or additional terms of any quote, order, acknowledgment, or other communication between the parties relating to its subject matter during the term of this Agreement. No modification to this Agreement will be binding, unless in writing and signed by an authorized representative
of each party.
Rev. April, 2006
4
4/2/13
Oracle
Java Persistence 2.1, Final Release
Table of Contents
Chapter 1
Introduction.................................................................................................................... 21
1.1 Expert Group ................................................................................................... 21
1.2 Document Conventions ................................................................................... 21
Chapter 2
Entities ........................................................................................................................... 23
2.1 The Entity Class .............................................................................................. 23
2.2 Persistent Fields and Properties....................................................................... 24
2.2.1 Example ............................................................................................ 26
2.3 Access Type..................................................................................................... 27
2.3.1 Default Access Type ......................................................................... 27
2.3.2 Explicit Access Type......................................................................... 28
2.3.3 Access Type of an Embeddable Class............................................... 29
2.3.4 Defaulted Access Types of Embeddable Classes and Mapped Superclasses
29
2.4 Primary Keys and Entity Identity .................................................................... 29
2.4.1 Primary Keys Corresponding to Derived Identities.......................... 31
2.4.1.1 Specification of Derived Identities ..................................... 31
2.4.1.2 Mapping of Derived Identities............................................ 32
2.4.1.3 Examples of Derived Identities .......................................... 32
2.5 Embeddable Classes ........................................................................................ 40
2.6 Collections of Embeddable Classes and Basic Types ..................................... 41
2.7 Map Collections .............................................................................................. 41
2.7.1 Map Keys .......................................................................................... 41
2.7.2 Map Values........................................................................................ 42
2.8 Mapping Defaults for Non-Relationship Fields or Properties......................... 42
2.9 Entity Relationships ........................................................................................ 43
2.10 Relationship Mapping Defaults....................................................................... 45
2.10.1 Bidirectional OneToOne Relationships ............................................ 45
2.10.2 Bidirectional ManyToOne / OneToMany Relationships................... 46
2.10.3 Unidirectional Single-Valued Relationships ..................................... 48
2.10.3.1 Unidirectional OneToOne Relationships............................ 48
2.10.3.2 Unidirectional ManyToOne Relationships ......................... 49
2.10.4 Bidirectional ManyToMany Relationships ....................................... 50
2.10.5 Unidirectional Multi-Valued Relationships ...................................... 51
2.10.5.1 Unidirectional OneToMany Relationships ......................... 52
2.10.5.2 Unidirectional ManyToMany Relationships....................... 53
2.11 Inheritance ....................................................................................................... 54
2.11.1 Abstract Entity Classes ..................................................................... 54
2.11.2 Mapped Superclasses ........................................................................ 55
2.11.3 Non-Entity Classes in the Entity Inheritance Hierarchy................... 57
2.12 Inheritance Mapping Strategies ....................................................................... 58
2.12.1 Single Table per Class Hierarchy Strategy........................................ 58
2.12.2 Joined Subclass Strategy ................................................................... 58
5
4/2/13
Oracle
Java Persistence 2.1, Final Release
2.12.3 Table per Concrete Class Strategy..................................................... 59
2.13 Naming of Database Objects ........................................................................... 59
Chapter 3
4/2/13
Entity Operations ........................................................................................................... 63
3.1 EntityManager ................................................................................................. 63
3.1.1 EntityManager Interface.................................................................... 65
3.1.2 Example of Use of EntityManager API ............................................ 80
3.2 Entity Instance’s Life Cycle ............................................................................ 80
3.2.1 Entity Instance Creation .................................................................... 81
3.2.2 Persisting an Entity Instance ............................................................. 81
3.2.3 Removal ............................................................................................ 81
3.2.4 Synchronization to the Database ....................................................... 82
3.2.5 Refreshing an Entity Instance ........................................................... 83
3.2.6 Evicting an Entity Instance from the Persistence Context ................ 84
3.2.7 Detached Entities............................................................................... 84
3.2.7.1 Merging Detached Entity State ........................................... 85
3.2.7.2 Detached Entities and Lazy Loading .................................. 86
3.2.8 Managed Instances ............................................................................ 86
3.2.9 Load State.......................................................................................... 86
3.3 Persistence Context Lifetime and Synchronization Type................................ 87
3.3.1 Synchronization with the Current Transaction.................................. 88
3.3.2 Transaction Commit .......................................................................... 88
3.3.3 Transaction Rollback......................................................................... 89
3.4 Locking and Concurrency ............................................................................... 89
3.4.1 Optimistic Locking............................................................................ 90
3.4.2 Version Attributes.............................................................................. 90
3.4.3 Pessimistic Locking........................................................................... 91
3.4.4 Lock Modes....................................................................................... 92
3.4.4.1 OPTIMISTIC, OPTIMISTIC_FORCE_INCREMENT...... 93
3.4.4.2 PESSIMISTIC_READ, PESSIMISTIC_WRITE,
PESSIMISTIC_FORCE_INCREMENT94
3.4.4.3 Lock Mode Properties and Uses ......................................... 96
3.4.5 OptimisticLockException.................................................................. 97
3.5 Entity Listeners and Callback Methods........................................................... 98
3.5.1 Entity Listeners ................................................................................. 98
3.5.2 Lifecycle Callback Methods.............................................................. 100
3.5.3 Semantics of the Life Cycle Callback Methods for Entities ............. 101
3.5.4 Example............................................................................................. 102
3.5.5 Multiple Lifecycle Callback Methods for an Entity Lifecycle Event102
3.5.6 Example............................................................................................. 103
3.5.7 Exceptions ......................................................................................... 105
3.5.8 Specification of Callback Listener Classes and Lifecycle Methods in the
XML Descriptor105
3.5.8.1 Specification of Callback Listeners .................................... 105
3.5.8.2 Specification of the Binding of Entity Listener Classes to Entities
106
3.6 Bean Validation................................................................................................ 106
3.6.1 Automatic Validation Upon Lifecycle Events................................... 107
6
Oracle
Java Persistence 2.1, Final Release
3.7
3.8
3.9
3.10
3.11
Chapter 4
3.6.1.1 Enabling Automatic Validation .......................................... 107
3.6.1.2 Requirements for Automatic Validation upon Lifecycle Events107
3.6.2 Providing the ValidatorFactory ......................................................... 108
Entity Graphs................................................................................................... 109
3.7.1 EntityGraph Interface........................................................................ 110
3.7.2 AttributeNode Interface .................................................................... 113
3.7.3 Subgraph Interface ............................................................................ 114
3.7.4 Use of Entity Graphs in find and query operations........................... 117
3.7.4.1 Fetch Graph Semantics ....................................................... 117
3.7.4.2 Load Graph Semantics........................................................ 120
Type Conversion of Basic Attributes .............................................................. 122
Caching............................................................................................................ 124
3.9.1 The shared-cache-mode Element ...................................................... 124
3.9.2 Cache Retrieve Mode and Cache Store Mode Properties ................. 125
Query APIs ...................................................................................................... 128
3.10.1 Query Interface ................................................................................. 128
3.10.2 TypedQuery Interface ....................................................................... 136
3.10.3 Tuple Interface .................................................................................. 140
3.10.4 TupleElement Interface ..................................................................... 141
3.10.5 Parameter Interface ........................................................................... 142
3.10.6 StoredProcedureQuery Interface....................................................... 143
3.10.7 Query Execution ............................................................................... 148
3.10.7.1 Example .............................................................................. 150
3.10.8 Queries and Flush Mode ................................................................... 150
3.10.9 Queries and Lock Mode.................................................................... 151
3.10.10 Query Hints ....................................................................................... 151
3.10.11 Parameter Objects ............................................................................. 152
3.10.12 Named Parameters ............................................................................ 152
3.10.13 Positional Parameters........................................................................ 152
3.10.14 Named Queries.................................................................................. 152
3.10.15 Polymorphic Queries......................................................................... 153
3.10.16 SQL Queries...................................................................................... 153
3.10.16.1 Returning Managed Entities from Native Queries ............. 153
3.10.16.2 Returning Unmanaged Instances ........................................ 157
3.10.16.2.1 Scalar Results ....................................................... 158
3.10.16.2.2 Constructor Results .............................................. 158
3.10.16.3 Combinations of Result Types............................................ 159
3.10.16.4 Restrictions ......................................................................... 159
3.10.17 Stored Procedures.............................................................................. 159
3.10.17.1 Named Stored Procedure Queries....................................... 160
3.10.17.2 Dynamically-specified Stored Procedure Queries.............. 160
3.10.17.3 Stored Procedure Query Execution .................................... 160
Summary of Exceptions .................................................................................. 161
Query Language............................................................................................................. 165
4.1 Overview ......................................................................................................... 165
4.2 Statement Types............................................................................................... 166
4.2.1 Select Statements .............................................................................. 166
7
4/2/13
Oracle
Java Persistence 2.1, Final Release
4.2.2 Update and Delete Statements........................................................... 167
4.3 Abstract Schema Types and Query Domains .................................................. 167
4.3.1 Naming .............................................................................................. 168
4.3.2 Example............................................................................................. 168
4.4 The FROM Clause and Navigational Declarations ......................................... 170
4.4.1 Identifiers .......................................................................................... 170
4.4.2 Identification Variables ..................................................................... 171
4.4.3 Range Variable Declarations ............................................................. 172
4.4.4 Path Expressions ............................................................................... 173
4.4.4.1 Path Expression Syntax ...................................................... 174
4.4.5 Joins................................................................................................... 175
4.4.5.1 Inner Joins (Relationship Joins).......................................... 176
4.4.5.2 Left Outer Joins .................................................................. 177
4.4.5.3 Fetch Joins .......................................................................... 178
4.4.6 Collection Member Declarations ...................................................... 178
4.4.7 FROM Clause and SQL .................................................................... 179
4.4.8 Polymorphism ................................................................................... 179
4.4.9 Downcasting...................................................................................... 179
4.5 WHERE Clause ............................................................................................... 180
4.6 Conditional Expressions .................................................................................. 181
4.6.1 Literals............................................................................................... 181
4.6.2 Identification Variables ..................................................................... 182
4.6.3 Path Expressions ............................................................................... 182
4.6.4 Input Parameters................................................................................ 182
4.6.4.1 Positional Parameters.......................................................... 182
4.6.4.2 Named Parameters .............................................................. 183
4.6.5 Conditional Expression Composition................................................ 183
4.6.6 Operators and Operator Precedence.................................................. 183
4.6.7 Comparison Expressions ................................................................... 184
4.6.8 Between Expressions......................................................................... 184
4.6.9 In Expressions ................................................................................... 185
4.6.10 Like Expressions ............................................................................... 186
4.6.11 Null Comparison Expressions........................................................... 187
4.6.12 Empty Collection Comparison Expressions...................................... 187
4.6.13 Collection Member Expressions ....................................................... 188
4.6.14 Exists Expressions............................................................................. 188
4.6.15 All or Any Expressions ..................................................................... 189
4.6.16 Subqueries ......................................................................................... 189
4.6.17 Scalar Expressions............................................................................. 191
4.6.17.1 Arithmetic Expressions....................................................... 191
4.6.17.2 Built-in String, Arithmetic, and Datetime Functional Expressions
191
4.6.17.2.1 String Functions.................................................... 191
4.6.17.2.2 Arithmetic Functions ............................................ 192
4.6.17.2.3 Datetime Functions............................................... 193
4.6.17.3 Invocation of Predefined and User-defined Database Functions193
4.6.17.4 Case Expressions ................................................................ 194
4.6.17.5 Entity Type Expressions ..................................................... 195
4.7 GROUP BY, HAVING .................................................................................... 196
4/2/13
8
Oracle
Java Persistence 2.1, Final Release
4.8 SELECT Clause .............................................................................................. 197
4.8.1 Result Type of the SELECT Clause.................................................. 198
4.8.2 Constructor Expressions in the SELECT Clause.............................. 199
4.8.3 Null Values in the Query Result........................................................ 200
4.8.4 Embeddables in the Query Result..................................................... 200
4.8.5 Aggregate Functions in the SELECT Clause.................................... 201
4.8.5.1 Examples ............................................................................ 202
4.8.6 Numeric Expressions in the SELECT Clause................................... 202
4.9 ORDER BY Clause ......................................................................................... 203
4.10 Bulk Update and Delete Operations ................................................................ 205
4.11 Null Values ...................................................................................................... 206
4.12 Equality and Comparison Semantics............................................................... 207
4.13 Examples ......................................................................................................... 208
4.13.1 Simple Queries.................................................................................. 208
4.13.2 Queries with Relationships ............................................................... 208
4.13.3 Queries Using Input Parameters ....................................................... 209
4.14 BNF ................................................................................................................. 210
Chapter 5
Metamodel API.............................................................................................................. 217
5.1 Metamodel API Interfaces............................................................................... 217
5.1.1 Metamodel Interface ......................................................................... 218
5.1.2 Type Interface ................................................................................... 219
5.1.3 ManagedType Interface..................................................................... 220
5.1.4 IdentifiableType Interface ................................................................. 226
5.1.5 EntityType Interface.......................................................................... 228
5.1.6 EmbeddableType Interface ............................................................... 228
5.1.7 MappedSuperclassType Interface ..................................................... 228
5.1.8 BasicType Interface........................................................................... 229
5.1.9 Bindable Interface ............................................................................. 229
5.1.10 Attribute Interface ............................................................................. 230
5.1.11 SingularAttribute Interface ............................................................... 231
5.1.12 PluralAttribute Interface ................................................................... 232
5.1.13 CollectionAttribute Interface ............................................................ 232
5.1.14 SetAttribute Interface........................................................................ 233
5.1.15 ListAttribute Interface....................................................................... 233
5.1.16 MapAttribute Interface...................................................................... 233
5.1.17 StaticMetamodel Annotation ............................................................ 234
Chapter 6
Criteria API.................................................................................................................... 235
6.1 Overview ......................................................................................................... 235
6.2 Metamodel....................................................................................................... 236
6.2.1 Static Metamodel Classes ................................................................. 236
6.2.1.1 Canonical Metamodel......................................................... 236
6.2.1.2 Example .............................................................................. 238
6.2.2 Bootstrapping .................................................................................... 238
6.3 Criteria API Interfaces..................................................................................... 239
9
4/2/13
Oracle
Java Persistence 2.1, Final Release
6.4
6.5
6.6
6.7
6.8
6.9
4/2/13
6.3.1 CriteriaBuilder Interface ................................................................... 239
6.3.2 CommonAbstractCriteria Interface ................................................... 268
6.3.3 AbstractQuery Interface .................................................................... 269
6.3.4 CriteriaQuery Interface ..................................................................... 272
6.3.5 CriteriaUpdate Interface.................................................................... 277
6.3.6 CriteriaDelete Interface ..................................................................... 280
6.3.7 Subquery Interface ............................................................................ 282
6.3.8 Selection Interface............................................................................. 286
6.3.9 CompoundSelection Interface ........................................................... 286
6.3.10 Expression Interface.......................................................................... 287
6.3.11 Predicate Interface............................................................................. 289
6.3.12 Path Interface..................................................................................... 290
6.3.13 FetchParent Interface......................................................................... 292
6.3.14 Fetch Interface................................................................................... 294
6.3.15 From Interface ................................................................................... 295
6.3.16 Root Interface.................................................................................... 299
6.3.17 Join Interface ..................................................................................... 300
6.3.18 JoinType ............................................................................................ 301
6.3.19 PluralJoin Interface ........................................................................... 301
6.3.20 CollectionJoin Interface .................................................................... 302
6.3.21 SetJoin Interface................................................................................ 303
6.3.22 ListJoin Interface............................................................................... 304
6.3.23 MapJoin Interface.............................................................................. 305
6.3.24 Order Interface .................................................................................. 306
6.3.25 ParameterExpression Interface.......................................................... 306
Criteria Query API Usage................................................................................ 307
Constructing Criteria Queries .......................................................................... 307
6.5.1 CriteriaQuery Creation...................................................................... 307
6.5.2 Query Roots....................................................................................... 308
6.5.3 Joins................................................................................................... 309
6.5.4 Fetch Joins......................................................................................... 311
6.5.5 Path Navigation ................................................................................. 311
6.5.6 Restricting the Query Result ............................................................. 312
6.5.7 Downcasting...................................................................................... 313
6.5.8 Expressions........................................................................................ 314
6.5.8.1 Result Types of Expressions ............................................... 317
6.5.9 Literals............................................................................................... 318
6.5.10 Parameter Expressions ...................................................................... 318
6.5.11 Specifying the Select List.................................................................. 319
6.5.11.1 Assigning Aliases to Selection Items.................................. 321
6.5.12 Subqueries ......................................................................................... 321
6.5.13 GroupBy and Having ........................................................................ 324
6.5.14 Ordering the Query Results............................................................... 325
6.5.15 Bulk Update and Delete Operations.................................................. 327
Constructing Strongly-typed Queries using the javax.persistence.metamodel Interfaces329
Use of the Criteria API with Strings to Reference Attributes ......................... 330
Query Modification ......................................................................................... 332
Query Execution .............................................................................................. 333
10
Oracle
Java Persistence 2.1, Final Release
Chapter 7
Entity Managers and Persistence Contexts .................................................................... 335
7.1 Persistence Contexts........................................................................................ 335
7.2 Obtaining an EntityManager ........................................................................... 336
7.2.1 Obtaining an Entity Manager in the Java EE Environment .............. 336
7.2.2 Obtaining an Application-managed Entity Manager ........................ 337
7.3 Obtaining an Entity Manager Factory ............................................................. 337
7.3.1 Obtaining an Entity Manager Factory in a Java EE Container ......... 338
7.3.2 Obtaining an Entity Manager Factory in a Java SE Environment .... 338
7.4 EntityManagerFactory Interface...................................................................... 338
7.5 Controlling Transactions ................................................................................. 342
7.5.1 JTA EntityManagers.......................................................................... 343
7.5.2 Resource-local EntityManagers ........................................................ 343
7.5.3 The EntityTransaction Interface........................................................ 343
7.5.4 Example ............................................................................................ 345
7.6 Container-managed Persistence Contexts ....................................................... 345
7.6.1 Persistence Context Synchronization Type....................................... 346
7.6.2 Container-managed Transaction-scoped Persistence Context .......... 347
7.6.3 Container-managed Extended Persistence Context .......................... 347
7.6.3.1 Inheritance of Extended Persistence Context ..................... 347
7.6.4 Persistence Context Propagation....................................................... 348
7.6.4.1 Requirements for Persistence Context Propagation ........... 348
7.6.5 Examples........................................................................................... 349
7.6.5.1 Container-managed Transaction-scoped Persistence Context349
7.6.5.2 Container-managed Extended Persistence Context ............ 350
7.7 Application-managed Persistence Contexts .................................................... 351
7.7.1 Examples........................................................................................... 352
7.7.1.1 Application-managed Persistence Context used in Stateless Session
Bean352
7.7.1.2 Application-managed Persistence Context used in Stateless Session
Bean353
7.7.1.3 Application-managed Persistence Context used in Stateful Session
Bean354
7.7.1.4 Application-managed Persistence Context with Resource Transaction355
7.8 Requirements on the Container ....................................................................... 356
7.8.1 Application-managed Persistence Contexts...................................... 356
7.8.2 Container Managed Persistence Contexts......................................... 356
7.9 Runtime Contracts between the Container and Persistence Provider ............. 356
7.9.1 Container Responsibilities ................................................................ 356
7.9.2 Provider Responsibilities .................................................................. 358
7.10 Cache Interface................................................................................................ 359
7.11 PersistenceUnitUtil Interface........................................................................... 360
Chapter 8
Entity Packaging ............................................................................................................ 361
8.1 Persistence Unit ............................................................................................... 361
8.2 Persistence Unit Packaging ............................................................................. 362
8.2.1 persistence.xml file ........................................................................... 363
11
4/2/13
Oracle
Java Persistence 2.1, Final Release
8.2.1.1
8.2.1.2
8.2.1.3
8.2.1.4
8.2.1.5
8.2.1.6
name.................................................................................... 364
transaction-type................................................................... 364
description........................................................................... 365
provider ............................................................................... 365
jta-data-source, non-jta-data-source.................................... 365
mapping-file, jar-file, class, exclude-unlisted-classes ........ 365
8.2.1.6.1 Annotated Classes in the Root of the Persistence Unit366
8.2.1.6.2 Object/relational Mapping Files ........................... 366
8.2.1.6.3 Jar Files................................................................. 366
8.2.1.6.4 List of Managed Classes....................................... 368
8.2.1.7 shared-cache-mode ............................................................. 368
8.2.1.8 validation-mode .................................................................. 368
8.2.1.9 properties ............................................................................ 369
8.2.1.10 Examples............................................................................. 371
8.2.2 Persistence Unit Scope ...................................................................... 373
8.3 persistence.xml Schema................................................................................... 374
Chapter 9
Container and Provider Contracts for Deployment and Bootstrapping ......................... 381
9.1 Java EE Deployment ....................................................................................... 381
9.2 Bootstrapping in Java SE Environments ......................................................... 383
9.2.1 Schema Generation ........................................................................... 384
9.3 Determining the Available Persistence Providers............................................ 384
9.3.1 PersistenceProviderResolver interface.............................................. 386
9.3.2 PersistenceProviderResolverHolder class ......................................... 386
9.4 Schema Generation.......................................................................................... 387
9.4.1 Data Loading ..................................................................................... 390
9.5 Responsibilities of the Persistence Provider.................................................... 390
9.5.1 javax.persistence.spi.PersistenceProvider ......................................... 391
9.5.2 javax.persistence.spi.ProviderUtil..................................................... 393
9.6 javax.persistence.spi.PersistenceUnitInfo Interface ........................................ 396
9.6.1 javax.persistence.spi.ClassTransformer Interface ............................. 400
9.7 javax.persistence.Persistence Class ................................................................. 401
9.8 PersistenceUtil Interface.................................................................................. 405
9.8.1 Contracts for Determining the Load State of an Entity or Entity Attribute
406
Chapter 10
Metadata Annotations .................................................................................................... 409
10.1 Entity ............................................................................................................... 409
10.2 Callback Annotations ...................................................................................... 410
10.3 EntityGraph Annotations ................................................................................. 411
10.3.1 NamedEntityGraph and NamedEntityGraphs Annotations .............. 411
10.3.2 NamedAttributeNode Annotation ..................................................... 411
10.3.3 NamedSubgraph Annotation ............................................................. 412
10.4 Annotations for Queries................................................................................... 413
10.4.1 NamedQuery Annotation .................................................................. 413
10.4.2 NamedNativeQuery Annotation........................................................ 413
4/2/13
12
Oracle
Java Persistence 2.1, Final Release
10.4.3 NamedStoredProcedureQuery Annotation........................................ 414
10.4.4 Annotations for SQL Result Set Mappings....................................... 416
10.5 References to EntityManager and EntityManagerFactory .............................. 417
10.5.1 PersistenceContext Annotation ......................................................... 417
10.5.2 PersistenceUnit Annotation............................................................... 418
10.6 Annotations for Type Converter Classes......................................................... 419
Chapter 11
Metadata for Object/Relational Mapping ...................................................................... 421
11.1 Annotations for Object/Relational Mapping ................................................... 421
11.1.1 Access Annotation ............................................................................ 422
11.1.2 AssociationOverride Annotation....................................................... 422
11.1.3 AssociationOverrides Annotation ..................................................... 425
11.1.4 AttributeOverride Annotation ........................................................... 426
11.1.5 AttributeOverrides Annotation ......................................................... 428
11.1.6 Basic Annotation............................................................................... 429
11.1.7 Cacheable Annotation ....................................................................... 430
11.1.8 CollectionTable Annotation .............................................................. 431
11.1.9 Column Annotation........................................................................... 433
11.1.10 Convert Annotation........................................................................... 435
11.1.11 Converts Annotation ......................................................................... 438
11.1.12 DiscriminatorColumn Annotation..................................................... 439
11.1.13 DiscriminatorValue Annotation ........................................................ 440
11.1.14 ElementCollection Annotation.......................................................... 441
11.1.15 Embeddable Annotation.................................................................... 442
11.1.16 Embedded Annotation....................................................................... 443
11.1.17 EmbeddedId Annotation ................................................................... 444
11.1.18 Enumerated Annotation .................................................................... 445
11.1.19 ForeignKey Annotation..................................................................... 446
11.1.20 GeneratedValue Annotation .............................................................. 447
11.1.21 Id Annotation .................................................................................... 449
11.1.22 IdClass Annotation............................................................................ 449
11.1.23 Index Annotation............................................................................... 450
11.1.24 Inheritance Annotation...................................................................... 450
11.1.25 JoinColumn Annotation .................................................................... 451
11.1.26 JoinColumns Annotation................................................................... 454
11.1.27 JoinTable Annotation ........................................................................ 455
11.1.28 Lob Annotation ................................................................................. 457
11.1.29 ManyToMany Annotation................................................................. 457
11.1.30 ManyToOne Annotation ................................................................... 460
11.1.31 MapKey Annotation.......................................................................... 462
11.1.32 MapKeyClass Annotation ................................................................. 463
11.1.33 MapKeyColumn Annotation............................................................. 465
11.1.34 MapKeyEnumerated Annotation ...................................................... 466
11.1.35 MapKeyJoinColumn Annotation ...................................................... 467
11.1.36 MapKeyJoinColumns Annotation..................................................... 470
11.1.37 MapKeyTemporal Annotation .......................................................... 471
11.1.38 MappedSuperclass Annotation ......................................................... 471
11.1.39 MapsId Annotation ........................................................................... 472
13
4/2/13
Oracle
Java Persistence 2.1, Final Release
11.1.40 OneToMany Annotation.................................................................... 473
11.1.41 OneToOne Annotation ...................................................................... 475
11.1.42 OrderBy Annotation.......................................................................... 478
11.1.43 OrderColumn Annotation.................................................................. 480
11.1.44 PrimaryKeyJoinColumn Annotation................................................. 482
11.1.45 PrimaryKeyJoinColumns Annotation ............................................... 484
11.1.46 SecondaryTable Annotation .............................................................. 485
11.1.47 SecondaryTables Annotation............................................................. 487
11.1.48 SequenceGenerator Annotation......................................................... 488
11.1.49 Table Annotation ............................................................................... 489
11.1.50 TableGenerator Annotation ............................................................... 490
11.1.51 Temporal Annotation......................................................................... 492
11.1.52 Transient Annotation......................................................................... 493
11.1.53 UniqueConstraint Annotation ........................................................... 493
11.1.54 Version Annotation............................................................................ 494
11.2 Object/Relational Metadata Used in Schema Generation ............................... 494
11.2.1 Table-level elements.......................................................................... 495
11.2.1.1 Table.................................................................................... 495
11.2.1.2 Inheritance .......................................................................... 496
11.2.1.3 SecondaryTable................................................................... 496
11.2.1.4 CollectionTable ................................................................... 496
11.2.1.5 JoinTable ............................................................................. 496
11.2.1.6 TableGenerator.................................................................... 496
11.2.2 Column-level elements...................................................................... 496
11.2.2.1 Column................................................................................ 497
11.2.2.2 MapKeyColumn.................................................................. 497
11.2.2.3 Enumerated, MapKeyEnumerated...................................... 497
11.2.2.4 Temporal, MapKeyTemporal .............................................. 498
11.2.2.5 Lob ...................................................................................... 498
11.2.2.6 OrderColumn ...................................................................... 498
11.2.2.7 DiscriminatorColumn ......................................................... 498
11.2.2.8 Version ................................................................................ 498
11.2.3 Primary Key mappings...................................................................... 498
11.2.3.1 Id ......................................................................................... 498
11.2.3.2 EmbeddedId ........................................................................ 499
11.2.3.3 GeneratedValue................................................................... 499
11.2.4 Foreign Key Column Mappings........................................................ 499
11.2.4.1 JoinColumn......................................................................... 499
11.2.4.2 MapKeyJoinColumn........................................................... 500
11.2.4.3 PrimaryKeyJoinColumn ..................................................... 500
11.2.4.4 ForeignKey ......................................................................... 500
11.2.5 Other Elements.................................................................................. 501
11.2.5.1 SequenceGenerator ............................................................. 501
11.2.5.2 Index ................................................................................... 501
11.2.5.3 UniqueConstraint ................................................................ 501
11.3 Examples of the Application of Annotations for Object/Relational Mapping 502
11.3.1 Examples of Simple Mappings ......................................................... 502
11.3.2 A More Complex Example ............................................................... 505
4/2/13
14
Oracle
Java Persistence 2.1, Final Release
Chapter 12
XML Object/Relational Mapping Descriptor ................................................................ 511
12.1 Use of the XML Descriptor............................................................................. 511
12.2 XML Overriding Rules.................................................................................... 512
12.2.1 persistence-unit-defaults Subelements.............................................. 512
12.2.1.1 schema ................................................................................ 512
12.2.1.2 catalog................................................................................. 512
12.2.1.3 delimited-identifiers............................................................ 513
12.2.1.4 access .................................................................................. 513
12.2.1.5 cascade-persist .................................................................... 513
12.2.1.6 entity-listeners .................................................................... 513
12.2.2 Other Subelements of the entity-mappings element ......................... 514
12.2.2.1 package ............................................................................... 514
12.2.2.2 schema ................................................................................ 514
12.2.2.3 catalog................................................................................. 514
12.2.2.4 access .................................................................................. 514
12.2.2.5 sequence-generator ............................................................. 514
12.2.2.6 table-generator .................................................................... 515
12.2.2.7 named-query ....................................................................... 515
12.2.2.8 named-native-query ............................................................ 515
12.2.2.9 named-stored-procedure-query........................................... 515
12.2.2.10 sql-result-set-mapping ........................................................ 515
12.2.2.11 entity ................................................................................... 515
12.2.2.12 mapped-superclass.............................................................. 516
12.2.2.13 embeddable ......................................................................... 516
12.2.2.14 converter ............................................................................. 516
12.2.3 entity Subelements and Attributes .................................................... 516
12.2.3.1 metadata-complete.............................................................. 516
12.2.3.2 access .................................................................................. 516
12.2.3.3 cacheable ............................................................................ 517
12.2.3.4 name.................................................................................... 517
12.2.3.5 table .................................................................................... 517
12.2.3.6 secondary-table ................................................................... 517
12.2.3.7 primary-key-join-column.................................................... 517
12.2.3.8 id-class ................................................................................ 517
12.2.3.9 inheritance .......................................................................... 517
12.2.3.10 discriminator-value ............................................................. 518
12.2.3.11 discriminator-column.......................................................... 518
12.2.3.12 sequence-generator ............................................................. 518
12.2.3.13 table-generator .................................................................... 518
12.2.3.14 attribute-override ................................................................ 518
12.2.3.15 association-override............................................................ 518
12.2.3.16 convert ................................................................................ 519
12.2.3.17 named-entity-graph............................................................. 519
12.2.3.18 named-query ....................................................................... 519
12.2.3.19 named-native-query ............................................................ 519
12.2.3.20 named-stored-procedure-query........................................... 519
12.2.3.21 sql-result-set-mapping ........................................................ 520
12.2.3.22 exclude-default-listeners..................................................... 520
12.2.3.23 exclude-superclass-listeners ............................................... 520
15
4/2/13
Oracle
Java Persistence 2.1, Final Release
12.2.3.24 entity-listeners..................................................................... 520
12.2.3.25 pre-persist, post-persist, pre-remove, post-remove, pre-update,
post-update, post-load520
12.2.3.26 attributes.............................................................................. 520
12.2.3.26.1 id ........................................................................... 520
12.2.3.26.2 embedded-id ......................................................... 521
12.2.3.26.3 basic...................................................................... 521
12.2.3.26.4 version .................................................................. 521
12.2.3.26.5 many-to-one.......................................................... 521
12.2.3.26.6 one-to-many.......................................................... 521
12.2.3.26.7 one-to-one............................................................. 521
12.2.3.26.8 many-to-many ...................................................... 521
12.2.3.26.9 element-collection ................................................ 521
12.2.3.26.10 embedded.............................................................. 521
12.2.3.26.11 transient ................................................................ 521
12.2.4 mapped-superclass Subelements and Attributes ............................... 522
12.2.4.1 metadata-complete .............................................................. 522
12.2.4.2 access .................................................................................. 522
12.2.4.3 id-class ................................................................................ 522
12.2.4.4 exclude-default-listeners..................................................... 522
12.2.4.5 exclude-superclass-listeners................................................ 522
12.2.4.6 entity-listeners..................................................................... 522
12.2.4.7 pre-persist, post-persist, pre-remove, post-remove, pre-update,
post-update, post-load523
12.2.4.8 attributes.............................................................................. 523
12.2.4.8.1 id ........................................................................... 523
12.2.4.8.2 embedded-id ......................................................... 523
12.2.4.8.3 basic...................................................................... 523
12.2.4.8.4 version .................................................................. 523
12.2.4.8.5 many-to-one.......................................................... 523
12.2.4.8.6 one-to-many.......................................................... 523
12.2.4.8.7 one-to-one............................................................. 523
12.2.4.8.8 many-to-many ...................................................... 524
12.2.4.8.9 element-collection ................................................ 524
12.2.4.8.10 embedded.............................................................. 524
12.2.4.8.11 transient ................................................................ 524
12.2.5 embeddable Subelements and Attributes .......................................... 524
12.2.5.1 metadata-complete .............................................................. 524
12.2.5.2 access .................................................................................. 524
12.2.5.3 attributes.............................................................................. 524
12.2.5.3.1 basic...................................................................... 525
12.2.5.3.2 many-to-one.......................................................... 525
12.2.5.3.3 one-to-many.......................................................... 525
12.2.5.3.4 one-to-one............................................................. 525
12.2.5.3.5 many-to-many ...................................................... 525
12.2.5.3.6 element-collection ................................................ 525
12.2.5.3.7 embedded.............................................................. 525
12.2.5.3.8 transient ................................................................ 525
12.3 XML Schema................................................................................................... 526
4/2/13
16
Oracle
Java Persistence 2.1, Final Release
Chapter 13
Related Documents ........................................................................................................ 563
Appendix A
Revision History ............................................................................................................ 565
A.1 Draft 1.............................................................................................................. 565
A.2 Draft 2.............................................................................................................. 566
A.3 Draft 3.............................................................................................................. 567
A.4 Draft 4.............................................................................................................. 567
A.5 Early Draft ....................................................................................................... 567
A.6 Draft 6.............................................................................................................. 568
A.7 Draft 7.............................................................................................................. 568
A.8 Draft 8.............................................................................................................. 568
A.9 Early Draft 2 .................................................................................................... 569
A.10 Public Draft ..................................................................................................... 569
A.11 Proposed Final Draft........................................................................................ 569
A.12 Final Release Draft .......................................................................................... 570
17
4/2/13
Oracle
Java Persistence 2.1, Final Release
4/2/13
18
Oracle
Java Persistence 2.1, Final Release
List of Tables
Table 1
Table 2
Table 3
Table 4
Table 5
Table 6
Table 7
Table 8
Table 9
Table 10
Table 11
Table 12
Table 13
Table 14
Table 15
Table 16
Table 17
Table 18
Table 19
Table 20
Table 21
Table 22
Table 23
Table 24
Table 25
Table 26
Table 27
Table 28
Table 29
Table 30
Table 31
Table 32
Table 33
Table 34
Table 35
Table 36
Table 37
Table 38
Table 39
Table 40
Table 41
Definition of the AND Operator ...........................................................................................................206
Definition of the OR Operator ..............................................................................................................207
Definition of the NOT Operator............................................................................................................207
Access Annotation Elements.................................................................................................................422
AssociationOverride Annotation Elements...........................................................................................423
AssociationOverrides Annotation Elements .........................................................................................425
AttributeOverride Annotation Elements ...............................................................................................426
AttributeOverrides Annotation Elements..............................................................................................428
Basic Annotation Elements ...................................................................................................................430
Cacheable Annotation Elements ...........................................................................................................430
CollectionTable Annotation Elements ..................................................................................................432
Column Annotation Elements ...............................................................................................................434
Convert Annotation Elements ...............................................................................................................435
Converts Annotation Elements..............................................................................................................438
DiscriminatorColumn Annotation Elements.........................................................................................440
DiscriminatorValue Annotation Elements.............................................................................................441
ElementCollection Annotation Elements ..............................................................................................442
Enumerated Annotation Elements.........................................................................................................446
ForeignKey Annotation Elements.........................................................................................................447
GeneratedValue Annotation Elements ..................................................................................................448
IdClass Annotation Elements ................................................................................................................449
Index Annotation Elements...................................................................................................................450
Inheritance Annotation Elements ..........................................................................................................451
JoinColumn Annotation Elements ........................................................................................................452
JoinColumns Annotation Elements.......................................................................................................454
JoinTable Annotation Elements ............................................................................................................456
ManyToMany Annotation Elements .....................................................................................................458
ManyToOne Annotation Elements........................................................................................................461
MapKey Annotation Elements ..............................................................................................................462
MapKeyClass Annotation Elements .....................................................................................................463
MapKeyColumn Annotation Elements .................................................................................................465
MapKeyEnumerated Annotation Elements...........................................................................................467
MapKeyJoinColumn Annotation Elements ..........................................................................................468
MapKeyJoinColumns Annotation Elements.........................................................................................471
MapKeyTemporal Annotation Elements...............................................................................................471
MapsId Annotation Elements................................................................................................................472
OneToMany Annotation Elements........................................................................................................474
OneToOne Annotation Elements ..........................................................................................................476
OrderBy Annotation Elements ..............................................................................................................479
OrderColumn Annotation Elements......................................................................................................481
PrimaryKeyJoinColumn Annotation Elements.....................................................................................483
19
4/2/13
Oracle
Java Persistence 2.1, Final Release
Table 42
Table 43
Table 44
Table 45
Table 46
Table 47
Table 48
Table 49
4/2/13
PrimaryKeyJoinColumns Annotation Elements....................................................................................484
SecondaryTable Annotation Elements ..................................................................................................486
SecondaryTables Annotation Elements .................................................................................................487
SequenceGenerator Annotation Elements.............................................................................................488
Table Annotation Elements ...................................................................................................................489
TableGenerator Annotation Elements ...................................................................................................490
Temporal Annotation Elements .............................................................................................................492
UniqueConstraint Annotation Elements................................................................................................493
20
Oracle
Java Persistence 2.1, Final Release
Ch apt er 1
Introduction
This document is the specification of the Java API for the management of persistence and object/relational mapping with Java EE and Java SE. The technical objective of this work is to provide an
object/relational mapping facility for the Java application developer using a Java domain model to manage a relational database.
The Java Persistence 2.1 specification adds support for schema generation, type conversion
methods, use of entity graphs in queries and find operations, unsynchronized persistence
contexts, stored procedure invocation, and injection into entity listener classes. It also
includes enhancements to the Java Persistence query language, the Criteria API, and to the
mapping of native queries.
1.1 Expert Group
This work is being conducted as part of JSR 338 under the Java Community Process Program. This
specification is the result of the collaborative work of the members of the JSR 338 Expert Group:
akquinet [email protected]: Michael Bouschen; Ericsson: Nicolas Seyvet; IBM: Kevin Sutter, Pinaki Poddar;
OW2: Florent Benoit; Oracle: Linda DeMichiel, Gordon Yorke, Michael Keith; Pramati Technologies:
Deepak Anupalli; Red Hat, Inc.: Emmanuel Bernard, Steve Ebersole, Scott Marlow; SAP AG: Rainer
Schweigkoffer; Sybase: Evan Ireland; Tmax Soft Inc.: Miju Byon; Versant: Christian von Kutzleben;
VMware: Oliver Gierke; individual members: Matthew Adams; Adam Bien; Bernd Mueller; Werner
Keil.
The work of the JSR 338 Expert Group is being conducted using the jpa-spec.java.net project.
1.2 Document Conventions
The regular Times font is used for information that is prescriptive by this specification.
The italic Times font is used for paragraphs that contain descriptive information, such as notes describing typical use, or notes clarifying the text with prescriptive specification.
The Courier font is used for code examples.
The Helvetica font is used to specify the BNF of the Java Persistence query language.
21
4/2/13
Oracle
Introduction
Java Persistence 2.1, Final Release
Document Conventions
This document is written in terms of the use of Java language metadata annotations. An XML descriptor
(as specified in Chapter 12) may be used as an alternative to annotations or to augment or override
annotations. The elements of this descriptor mirror the annotations and have the same semantics. When
semantic requirements are written in terms of annotations, it should be understood that the same semantics apply when the XML descriptor is used as an alternative.
4/2/13
22
JSR-338 Final Release
Oracle
The Entity Class
Ch apt er 2
Java Persistence 2.1, Final Release
Entities
Entities
An entity is a lightweight persistent domain object.
The primary programming artifact is the entity class. An entity class may make use of auxiliary classes
that serve as helper classes or that are used to represent the state of the entity.
This chapter describes requirements on entity classes and instances.
2.1 The Entity Class
The entity class must be annotated with the Entity annotation or denoted in the XML descriptor as an
entity.
The entity class must have a no-arg constructor. The entity class may have other constructors as well.
The no-arg constructor must be public or protected.
The entity class must be a top-level class. An enum or interface must not be designated as an entity.
The entity class must not be final. No methods or persistent instance variables of the entity class may be
final.
JSR-338 Final Release
23
4/2/13
Oracle
Entities
Java Persistence 2.1, Final Release
Persistent Fields and Properties
If an entity instance is to be passed by value as a detached object (e.g., through a remote interface), the
entity class must implement the Serializable interface.
Entities support inheritance, polymorphic associations, and polymorphic queries.
Both abstract and concrete classes can be entities. Entities may extend non-entity classes as well as
entity classes, and non-entity classes may extend entity classes.
The persistent state of an entity is represented by instance variables, which may correspond to JavaBeans properties. An instance variable must be directly accessed only from within the methods of the
entity by the entity instance itself. Instance variables must not be accessed by clients of the entity. The
state of the entity is available to clients only through the entity’s methods—i.e., accessor methods (getter/setter methods) or other business methods.
2.2 Persistent Fields and Properties
The persistent state of an entity is accessed by the persistence provider runtime[1] either via JavaBeans
style property accessors (“property access”) or via instance variables (“field access”). Whether persistent properties or persistent fields or a combination of the two is used for the provider’s access to a
given class or entity hierarchy is determined as described in Section 2.3, “Access Type”.
Terminology Note: The persistent fields and properties of an entity class are generically
referred to in this document as the “attributes” of the class.
The instance variables of a class must be private, protected, or package visibility independent of
whether field access or property access is used. When property access is used, the property accessor
methods must be public or protected.
It is required that the entity class follow the method signature conventions for JavaBeans read/write
properties (as defined by the JavaBeans Introspector class) for persistent properties when property
access is used.
In this case, for every persistent property property of type T of the entity, there is a getter method, getProperty, and setter method setProperty. For boolean properties, isProperty may be used as an alternative name for the getter method.[2]
For single-valued persistent properties, these method signatures are:
• T getProperty()
• void setProperty(T t)
4/2/13
[1]
The term "persistence provider runtime" refers to the runtime environment of the persistence implementation. In Java EE environments, this may be the Java EE container or a third-party persistence provider implementation integrated with it.
[2]
Specifically, if getX is the name of the getter method and setX is the name of the setter method, where X is a string, the name of the
persistent property is defined by the result of java.beans.Introspector.decapitalize(X).
24
JSR-338 Final Release
Oracle
Persistent Fields and Properties
Java Persistence 2.1, Final Release
Entities
Collection-valued persistent fields and properties must be defined in terms of one of the following collection-valued interfaces regardless of whether the entity class otherwise adheres to the JavaBeans
method conventions noted above and whether field or property access is used: java.util.Collection, java.util.Set, java.util.List[3], java.util.Map. The collection implementation type may be used by the application to initialize fields or properties before the entity is made
persistent. Once the entity becomes managed (or detached), subsequent access must be through the
interface type.
Terminology Note: The terms “collection” and “collection-valued” are used in this specification to denote any of the above types unless further qualified. In cases where a
java.util.Collection type (or one of its subtypes) is to be distinguished, the type is
identified as such. The terms “map” and “map collection” are used to apply to a collection of
type java.util.Map when a collection of type java.util.Map needs to be distinguished as such.
For collection-valued persistent properties, type T must be one of these collection interface types in the
method signatures above. Use of the generic variants of these collection types is encouraged (for example, Set<Order>).
In addition to returning and setting the persistent state of the instance, property accessor methods may
contain other business logic as well, for example, to perform validation. The persistence provider runtime executes this logic when property-based access is used.
Caution should be exercised in adding business logic to the accessor methods when property
access is used. The order in which the persistence provider runtime calls these methods when
loading or storing persistent state is not defined. Logic contained in such methods therefore
should not rely upon a specific invocation order.
If property access is used and lazy fetching is specified, portable applications should not directly access
the entity state underlying the property methods of managed instances until after it has been fetched by
the persistence provider.[4]
If a persistence context is joined to a transaction, runtime exceptions thrown by property accessor methods cause the current transaction to be marked for rollback; exceptions thrown by such methods when
used by the persistence runtime to load or store persistent state cause the persistence runtime to mark
the current transaction for rollback and to throw a PersistenceException that wraps the application exception.
Entity subclasses may override the property accessor methods. However, portable applications must not
override the object/relational mapping metadata that applies to the persistent fields or properties of
entity superclasses.
[3]
Portable applications should not expect the order of a list to be maintained across persistence contexts unless the OrderColumn
construct is used or unless the OrderBy construct is used and the modifications to the list observe the specified ordering.
[4]
Lazy fetching is a hint to the persistence provider and can be specified by means of the Basic, OneToOne, OneToMany,
ManyToOne, ManyToMany, and ElementCollection annotations and their XML equivalents. See Chapter 11.
JSR-338 Final Release
25
4/2/13
Oracle
Entities
Java Persistence 2.1, Final Release
Persistent Fields and Properties
The persistent fields or properties of an entity may be of the following types: Java primitive types;
java.lang.String; other Java serializable types (including wrappers of the primitive types,
java.math.BigInteger,
java.math.BigDecimal,
java.util.Date,
java.util.Calendar[5], java.sql.Date, java.sql.Time, java.sql.Timestamp,
byte[], Byte[], char[], Character[], and user-defined types that implement the Serializable interface); enums; entity types; collections of entity types; embeddable classes (see Section
2.5); collections of basic and embeddable types (see Section 2.6).
Object/relational mapping metadata may be specified to customize the object/relational mapping and
the loading and storing of the entity state and relationships. See Chapter 11.
2.2.1 Example
@Entity
public class Customer implements Serializable {
private Long id;
private String name;
private Address address;
private Collection<Order> orders = new HashSet();
private Set<PhoneNumber> phones = new HashSet();
// No-arg constructor
public Customer() {}
@Id
// property access is used
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
[5]
4/2/13
Note that an instance of Calendar must be fully initialized for the type that it is mapped to.
26
JSR-338 Final Release
Oracle
Access Type
Java Persistence 2.1, Final Release
Entities
@OneToMany
public Collection<Order> getOrders() {
return orders;
}
public void setOrders(Collection<Order> orders) {
this.orders = orders;
}
@ManyToMany
public Set<PhoneNumber> getPhones() {
return phones;
}
public void setPhones(Set<PhoneNumber> phones) {
this.phones = phones;
}
}
// Business method to add a phone number to the customer
public void addPhone(PhoneNumber phone) {
this.getPhones().add(phone);
// Update the phone entity instance to refer to this customer
phone.addCustomer(this);
}
2.3 Access Type
2.3.1 Default Access Type
By default, a single access type (field or property access) applies to an entity hierarchy. The default
access type of an entity hierarchy is determined by the placement of mapping annotations on the
attributes of the entity classes and mapped superclasses of the entity hierarchy that do not explicitly
specify an access type. An access type is explicitly specified by means of the Access annotation[6], as
described in section 2.3.2.
When annotations are used to define a default access type, the placement of the mapping annotations on
either the persistent fields or persistent properties of the entity class specifies the access type as being
either field- or property-based access respectively.
• When field-based access is used, the object/relational mapping annotations for the entity class
annotate the instance variables, and the persistence provider runtime accesses instance variables directly. All non-transient instance variables that are not annotated with the Transient annotation are persistent.
• When property-based access is used, the object/relational mapping annotations for the entity
class annotate the getter property accessors[7], and the persistence provider runtime accesses
[6]
The use of XML as an alternative and the interaction between Java language annotations and XML elements in defining default
and explicit access types is described in Chapter 12.
JSR-338 Final Release
27
4/2/13
Oracle
Entities
Java Persistence 2.1, Final Release
Access Type
persistent state via the property accessor methods. All properties not annotated with the
Transient annotation are persistent.
• Mapping annotations must not be applied to fields or properties that are transient or
Transient.
All such classes in the entity hierarchy whose access type is defaulted in this way must be consistent in
their placement of annotations on either fields or properties, such that a single, consistent default access
type applies within the hierarchy. Any embeddable classes used by such classes will have the same
access type as the default access type of the hierarchy unless the Access annotation is specified as
defined below.
It is an error if a default access type cannot be determined and an access type is not explicitly specified
by means of annotations or the XML descriptor. The behavior of applications that mix the placement of
annotations on fields and properties within an entity hierarchy without explicitly specifying the
Access annotation is undefined.
2.3.2 Explicit Access Type
An access type for an individual entity class, mapped superclass, or embeddable class can be specified
for that class independent of the default for the entity hierarchy by means of the Access annotation
applied to the class. This explicit access type specification does not affect the access type of other entity
classes or mapped superclasses in the entity hierarchy. The following rules apply:
• When Access(FIELD) is applied to an entity class, mapped superclass, or embeddable
class, mapping annotations may be placed on the instance variables of that class, and the persistence provider runtime accesses persistent state via the instance variables defined by the
class. All non-transient instance variables that are not annotated with the Transient annotation are persistent. When Access(FIELD) is applied to such a class, it is possible to
selectively designate individual attributes within the class for property access. To specify a
persistent property for access by the persistence provider runtime, that property must be designated Access(PROPERTY).[8] The behavior is undefined if mapping annotations are placed
on any properties defined by the class for which Access(PROPERTY) is not specified. Persistent state inherited from superclasses is accessed in accordance with the access types of
those superclasses.
• When Access(PROPERTY) is applied to an entity class, mapped superclass, or embeddable
class, mapping annotations may be placed on the properties of that class, and the persistence
provider runtime accesses persistent state via the properties defined by that class. All properties that are not annotated with the Transient annotation are persistent. When
Access(PROPERTY) is applied to such a class, it is possible to selectively designate individual attributes within the class for instance variable access. To specify a persistent instance
variable for access by the persistence provider runtime, that instance variable must be designated Access(FIELD). The behavior is undefined if mapping annotations are placed on any
4/2/13
[7]
These annotations must not be applied to the setter methods.
[8]
It is permitted (but redundant) to place Access(FIELD) on a persistent field whose class has field access type or Access(PROPERTY) on a persistent property whose class has property access type. It is not permitted to specify a field as Access(PROPERTY)
or a property as Access(FIELD). Note that Access(PROPERTY) must not be placed on the setter methods.
28
JSR-338 Final Release
Oracle
Primary Keys and Entity Identity
Java Persistence 2.1, Final Release
Entities
instance variables defined by the class for which Access(FIELD) is not specified. Persistent state inherited from superclasses is accessed in accordance with the access types of those
superclasses.
Note that when access types are combined within a class, the Transient annotation should
be used to avoid duplicate persistent mappings.
2.3.3 Access Type of an Embeddable Class
The access type of an embeddable class is determined by the access type of the entity class, mapped
superclass, or embeddable class in which it is embedded (including as a member of an element collection) independent of whether the access type of the containing class has been explicitly specified or
defaulted. A different access type for an embeddable class can be specified for that embeddable class
by means of the Access annotation as described above.
2.3.4 Defaulted Access Types of Embeddable Classes and Mapped Superclasses
Care must be exercised when defining an embeddable class or mapped superclass which is used both in
a context of field access and in a context of property access and whose access type is not explicitly specified by means of the Access annotation or XML mapping file.
Such classes should be defined so that the number, names, and types of the resulting persistent attributes
are identical, independent of the access type in use. The behavior of such classes whose attributes are
not independent of access type is otherwise undefined with regard to use with the metamodel API if
they occur in contexts of differing access types within the same persistence unit.
2.4 Primary Keys and Entity Identity
Every entity must have a primary key.
The primary key must be defined on the entity class that is the root of the entity hierarchy or on a
mapped superclass that is a (direct or indirect) superclass of all entity classes in the entity hierarchy. The
primary key must be defined exactly once in an entity hierarchy.
A primary key corresponds to one or more fields or properties (“attributes”) of the entity class.
• A simple (i.e., non-composite) primary key must correspond to a single persistent field or
property of the entity class. The Id annotation or id XML element must be used to denote a
simple primary key. See Section 11.1.21.
• A composite primary key must correspond to either a single persistent field or property or to a
set of such fields or properties as described below. A primary key class must be defined to represent a composite primary key. Composite primary keys typically arise when mapping from
legacy databases when the database key is comprised of several columns. The EmbeddedId
or IdClass annotation is used to denote a composite primary key. See Sections 11.1.17 and
11.1.22.
JSR-338 Final Release
29
4/2/13
Oracle
Entities
Java Persistence 2.1, Final Release
Primary Keys and Entity Identity
A simple primary key or a field or property of a composite primary key should be one of the following
types: any Java primitive type; any primitive wrapper type; java.lang.String;
java.util.Date; java.sql.Date; java.math.BigDecimal; java.math.BigInteger.[9] If the primary key is a composite primary key derived from the primary key of another entity,
the primary key may contain an attribute whose type is that of the primary key of the referenced entity
as described in Section 2.4.1. Entities whose primary keys use types other than these will not be portable. If generated primary keys are used, only integral types will be portable. If java.util.Date is
used as a primary key field or property, the temporal type should be specified as DATE.
The following rules apply for composite primary keys:
• The primary key class must be public and must have a public no-arg constructor.
• The access type (field- or property-based access) of a primary key class is determined by the
access type of the entity for which it is the primary key unless the primary key is a embedded
id and a different access type is specified. See Section 2.3, “Access Type”.
• If property-based access is used, the properties of the primary key class must be public or protected.
• The primary key class must be serializable.
• The primary key class must define equals and hashCode methods. The semantics of value
equality for these methods must be consistent with the database equality for the database types
to which the key is mapped.
• A composite primary key must either be represented and mapped as an embeddable class (see
Section 11.1.17, “EmbeddedId Annotation”) or must be represented as an id class and mapped
to multiple fields or properties of the entity class (see Section 11.1.22, “IdClass Annotation”).
• If the composite primary key class is represented as an id class, the names of primary key
fields or properties in the primary key class and those of the entity class to which the id class is
mapped must correspond and their types must be the same.
• A primary key that corresponds to a derived identity must conform to the rules of Section
2.4.1.
The value of its primary key uniquely identifies an entity instance within a persistence context and to
EntityManager operations as described in Chapter 3, “Entity Operations”. The application must not
change the value of the primary key[10]. The behavior is undefined if this occurs.[11]
[9]
In general, however, approximate numeric types (e.g., floating point types) should never be used in primary keys.
[10] This includes not changing the value of a mutable type that is primary key or an attribute of a composite primary key.
[11] The implementation may, but is not required to, throw an exception. Portable applications must not rely on any such specific
behavior.
4/2/13
30
JSR-338 Final Release
Oracle
Primary Keys and Entity Identity
Java Persistence 2.1, Final Release
Entities
2.4.1 Primary Keys Corresponding to Derived Identities
The identity of an entity may be derived from the identity of another entity (the “parent” entity) when
the former entity (the “dependent” entity) is the owner of a many-to-one or one-to-one relationship to
the parent entity and a foreign key maps the relationship from dependent to parent.
If a many-to-one or one-to-one entity relationship corresponds to a primary key attribute, the entity containing this relationship cannot be persisted without the relationship having been assigned an entity
since the identity of the entity containing the relationship is derived from the referenced entity.[12]
Derived identities may be captured by means of simple primary keys or by means of composite primary
keys as described in subsection 2.4.1.1 below.
If the dependent entity class has primary key attributes in addition to those corresponding to the parent's
primary key or if the parent has a composite primary key, an embedded id or id class must be used to
specify the primary key of the dependent entity. It is not necessary that parent entity and dependent
entity both use embedded ids or both use id classes to represent composite primary keys when the parent has a composite key.
A dependent entity may have more than one parent entity.
2.4.1.1 Specification of Derived Identities
If the dependent entity uses an id class to represent its primary key, one of the two following rules must
be observed:
• The names of the attributes of the id class and the Id attributes of the dependent entity class
must correspond as follows:
• The Id attribute in the entity class and the corresponding attribute in the id class must
have the same name.
• If an Id attribute in the entity class is of basic type, the corresponding attribute in the
id class must have the same type.
• If an Id attribute in the entity is a many-to-one or one-to-one relationship to a parent
entity, the corresponding attribute in the id class must be of the same Java type as the
id class or embedded id of the parent entity (if the parent entity has a composite primary key) or the type of the Id attribute of the parent entity (if the parent entity has a
simple primary key).
• If the dependent entity has a single primary key attribute (i.e., the relationship attribute), the id
class specified by the dependent entity must be the same as the primary key class of the parent
entity. The Id annotation is applied to the relationship to the parent entity.[13]
[12] If the application does not set the primary key attribute corresponding to the relationship, the value of that attribute may not be
available until after the entity has been flushed to the database.
[13] Note that it is correct to observe the first rule as an alternative in this case.
JSR-338 Final Release
31
4/2/13
Oracle
Entities
Java Persistence 2.1, Final Release
Primary Keys and Entity Identity
If the dependent entity uses an embedded id to represent its primary key, the attribute in the embedded
id corresponding to the relationship attribute must be of the same type as the primary key of the parent
entity and must be designated by the MapsId annotation applied to the relationship attribute. The
value element of the MapsId annotation must be used to specify the name of the attribute within the
embedded id to which the relationship attribute corresponds. If the embedded id of the dependent entity
is of the same Java type as the primary key of the parent entity, the relationship attribute maps both the
relationship to the parent and the primary key of the dependent entity, and in this case the MapsId
annotation is specified without the value element.[14]
If the dependent entity has a single primary key attribute (i.e, the relationship attribute or an attribute
that corresponds to the relationship attribute) and the primary key of the parent entity is a simple primary key, the primary key of the dependent entity is a simple primary key of the same type as that of the
parent entity (and neither EmbeddedId nor IdClass is specified). In this case, either (1) the relationship attribute is annotated Id, or (2) a separate Id attribute is specified and the relationship attribute
is annotated MapsId (and the value element of the MapsId annotation is not specified).
2.4.1.2 Mapping of Derived Identities
A primary key attribute that is derived from the identity of a parent entity is mapped by the corresponding relationship attribute. The default mapping for this relationship is as specified in section 2.10. In
the case where a default mapping does not apply or where a default mapping is to be overridden, the
JoinColumn or JoinColumns annotation is used on the relationship attribute.
If the dependent entity uses an embedded id to represent its primary key, the AttributeOverride
annotation may be used to override the default mapping of embedded id attributes that do not correspond to the relationship attributes mapping the derived identity. The embedded id attributes that correspond to the relationship are treated by the provider as “read only”—that is, any updates to them on
the part of the application are not propagated to the database.
If the dependent uses an id class, the Column annotation may be used to override the default mapping
of Id attributes that are not relationship attributes.
2.4.1.3 Examples of Derived Identities
Example 1:
The parent entity has a simple primary key:
@Entity
public class Employee {
@Id long empId;
String empName;
...
}
[14] Note that the parent’s primary key might be represented as either an embedded id or as an id class.
4/2/13
32
JSR-338 Final Release
Oracle
Primary Keys and Entity Identity
Java Persistence 2.1, Final Release
Entities
Case (a): The dependent entity uses IdClass to represent a composite key:
public class DependentId {
String name; // matches name of @Id attribute
long emp; // matches name of @Id attribute and type of Employee PK
}
@Entity
@IdClass(DependentId.class)
public class Dependent {
@Id String name;
}
// id attribute mapped by join column default
@Id @ManyToOne Employee emp;
...
Sample query:
SELECT d
FROM Dependent d
WHERE d.name = 'Joe' AND d.emp.empName = 'Sam'
Case(b): The dependent entity uses EmbeddedId to represent a composite key:
@Embeddable
public class DependentId {
String name;
long empPK;
// corresponds to PK type of Employee
}
@Entity
public class Dependent {
@EmbeddedId DependentId id;
...
// id attribute mapped by join column default
@MapsId("empPK") // maps empPK attribute of embedded id
@ManyToOne Employee emp;
}
Sample query:
SELECT d
FROM Dependent d
WHERE d.id.name = 'Joe' AND d.emp.empName = 'Sam'
JSR-338 Final Release
33
4/2/13
Oracle
Entities
Java Persistence 2.1, Final Release
Primary Keys and Entity Identity
Example 2:
The parent entity uses IdClass:
public class EmployeeId {
String firstName;
String lastName;
...
}
@Entity
@IdClass(EmployeeId.class)
public class Employee {
@Id String firstName
@Id String lastName
...
}
Case (a): The dependent entity uses IdClass:
public class DependentId {
String name;
// matches name of attribute
EmployeeId emp; //matches name of attribute and type of Employee PK
}
@Entity
@IdClass(DependentId.class)
public class Dependent {
@Id String name;
}
@Id
@JoinColumns({
@JoinColumn(name="FK1", referencedColumnName="firstName"),
@JoinColumn(name="FK2", referencedColumnName="lastName")
})
@ManyToOne Employee emp;
Sample query:
SELECT d
FROM Dependent d
WHERE d.name = 'Joe' AND d.emp.firstName = 'Sam'
Case (b): The dependent entity uses EmbeddedId. The type of the empPK attribute is the same as that
of the primary key of Employee. The EmployeeId class needs to be annotated Embeddable or
denoted as an embeddable class in the XML descriptor.
@Embeddable
public class DependentId {
String name;
EmployeeId empPK;
}
4/2/13
34
JSR-338 Final Release
Oracle
Primary Keys and Entity Identity
Java Persistence 2.1, Final Release
Entities
@Entity
public class Dependent {
@EmbeddedId DependentId id;
...
@MapsId("empPK")
@JoinColumns({
@JoinColumn(name="FK1", referencedColumnName="firstName"),
@JoinColumn(name="FK2", referencedColumnName="lastName")
})
@ManyToOne Employee emp;
}
Sample query:
SELECT d
FROM Dependent d
WHERE d.id.name = 'Joe' AND d.emp.firstName = 'Sam'
Note that the following alternative query will yield the same result:
SELECT d
FROM Dependent d
WHERE d.id.name = 'Joe' AND d.id.empPK.firstName = 'Sam'
Example 3:
The parent entity uses EmbeddedId:
@Embeddable
public class EmployeeId {
String firstName;
String lastName;
...
}
@Entity
public class Employee {
@EmbeddedId EmployeeId empId;
...
}
Case (a): The dependent entity uses IdClass:
public class DependentId {
String name;
// matches name of @Id attribute
EmployeeId emp; // matches name of @Id attribute and type of embedded id of Employee
JSR-338 Final Release
35
4/2/13
Oracle
Entities
Java Persistence 2.1, Final Release
Primary Keys and Entity Identity
@Entity
@IdClass(DependentId.class)
public class Dependent {
@Id
@Column(name="dep_name") // default column name is overridden
String name;
}
@Id
@JoinColumns({
@JoinColumn(name="FK1", referencedColumnName="firstName"),
@JoinColumn(name="FK2", referencedColumnName="lastName")
})
@ManyToOne Employee emp;
Sample query:
SELECT d
FROM Dependent d
WHERE d.name = 'Joe' and d.emp.empId.firstName = 'Sam'
Case (b): The dependent entity uses EmbeddedId:
@Embeddable
public class DependentId {
String name;
EmployeeId empPK;
// corresponds to PK type of Employee
}
@Entity
public class Dependent {
// default column name for "name" attribute is overridden
@AttributeOverride(name="name", [email protected](name="dep_name"))
@EmbeddedId DependentId id;
...
@MapsId("empPK")
@JoinColumns({
@JoinColumn(name="FK1", referencedColumnName="firstName"),
@JoinColumn(name="FK2", referencedColumnName="lastName")
})
@ManyToOne Employee emp;
}
Sample query:
SELECT d
FROM Dependent d
WHERE d.id.name = 'Joe' and d.emp.empId.firstName = 'Sam'
Note that the following alternative query will yield the same result:
SELECT d
FROM Dependent d
WHERE d.id.name = 'Joe' AND d.id.empPK.firstName = 'Sam'
4/2/13
36
JSR-338 Final Release
Oracle
Primary Keys and Entity Identity
Java Persistence 2.1, Final Release
Entities
Example 4:
The parent entity has a simple primary key:
@Entity
public class Person {
@Id String ssn;
...
}
Case (a): The dependent entity has a single primary key attribute which is mapped by the relationship
attribute. The primary key of MedicalHistory is of type String.
@Entity
public class MedicalHistory {
// default join column name is overridden
@Id
@OneToOne
@JoinColumn(name="FK")
Person patient;
...
}
Sample query:
SELECT m
FROM MedicalHistory m
WHERE m.patient.ssn = '123-45-6789'
Case (b): The dependent entity has a single primary key attribute corresponding to the relationship
attribute. The primary key attribute is of the same basic type as the primary key of the parent entity. The
MapsId annotation applied to the relationship attribute indicates that the primary key is mapped by the
relationship attribute. [15]
@Entity
public class MedicalHistory {
@Id String id; // overriding not allowed
...
// default join column name is overridden
@MapsId
@JoinColumn(name="FK")
@OneToOne Person patient;
...
}
Sample query:
SELECT m
FROM MedicalHistory m WHERE m.patient.ssn = '123-45-6789'
[15] Note that the use of PrimaryKeyJoinColumn instead of MapsId would result in the same mapping in this example. Use of MapsId
is preferred for the mapping of derived identities.
JSR-338 Final Release
37
4/2/13
Oracle
Entities
Java Persistence 2.1, Final Release
Primary Keys and Entity Identity
Example 5:
The parent entity uses IdClass. The dependent's primary key class is of same type as that of the parent entity.
public class PersonId {
String firstName;
String lastName;
}
@Entity
@IdClass(PersonId.class)
public class Person {
@Id String firstName;
@Id String lastName;
...
}
Case (a): The dependent entity uses IdClass:
@Entity
@IdClass(PersonId.class)
public class MedicalHistory {
@Id
@JoinColumns({
@JoinColumn(name="FK1", referencedColumnName="firstName"),
@JoinColumn(name="FK2", referencedColumnName="lastName")
})
@OneToOne
Person patient;
...
}
Sample query:
SELECT m
FROM MedicalHistory m
WHERE m.patient.firstName = 'Charles'
Case (b): The dependent entity uses the EmbeddedId and MapsId annotations. The PersonId
class needs to be annotated Embeddable or denoted as an embeddable class in the XML descriptor.
@Entity
public class MedicalHistory {
//all attributes map to relationship: AttributeOverride not allowed
@EmbeddedId PersonId id;
...
@MapsId
@JoinColumns({
@JoinColumn(name="FK1", referencedColumnName="firstName"),
@JoinColumn(name="FK2", referencedColumnName="lastName")
})
@OneToOne Person patient;
...
}
4/2/13
38
JSR-338 Final Release
Oracle
Primary Keys and Entity Identity
Java Persistence 2.1, Final Release
Entities
Sample query:
SELECT m
FROM MedicalHistory m
WHERE m.patient.firstName = 'Charles'
Note that the following alternative query will yield the same result:
SELECT m
FROM MedicalHistory m
WHERE m.id.firstName = 'Charles'
Example 6:
The parent entity uses EmbeddedId. The dependent's primary key is of the same type as that of the
parent.
@Embeddable
public class PersonId {
String firstName;
String lastName;
}
@Entity
public class Person {
@EmbeddedId PersonId id;
...
}
Case (a): The dependent class uses IdClass:
@Entity
@IdClass(PersonId.class)
public class MedicalHistory {
@Id
@OneToOne
@JoinColumns({
@JoinColumn(name="FK1", referencedColumnName="firstName"),
@JoinColumn(name="FK2", referencedColumnName="lastName")
})
Person patient;
...
}
JSR-338 Final Release
39
4/2/13
Oracle
Entities
Java Persistence 2.1, Final Release
Embeddable Classes
Case (b): The dependent class uses EmbeddedId:
@Entity
public class MedicalHistory {
// All attributes are mapped by the relationship:
// AttributeOverride is not allowed
@EmbeddedId PersonId id;
...
@MapsId
@JoinColumns({
@JoinColumn(name="FK1", referencedColumnName="firstName"),
@JoinColumn(name="FK2", referencedColumnName="lastName")
})
@OneToOne
Person patient;
...
}
2.5 Embeddable Classes
An entity may use other fine-grained classes to represent entity state. Instances of these classes, unlike
entity instances, do not have persistent identity of their own. Instead, they exist only as part of the state
of the entity to which they belong. An entity may have collections of embeddables as well as single-valued embeddable attributes. Embeddables may also be used as map keys and map values. Embedded
objects belong strictly to their owning entity, and are not sharable across persistent entities. Attempting
to share an embedded object across entities has undefined semantics.
Embeddable classes must adhere to the requirements specified in Section 2.1 for entities with the exception that embeddable classes are not annotated as Entity. Embeddable classes must be annotated as
Embeddable or denoted in the XML descriptor as such. The access type for an embedded object is
determined as described in Section 2.3, “Access Type”.
An embeddable class may be used to represent the state of another embeddable class.
An embeddable class (including an embeddable class within another embeddable class) may contain a
collection of a basic type or other embeddable class.[16]
An embeddable class may contain a relationship to an entity or collection of entities. Since instances of
embeddable classes themselves have no persistent identity, the relationship from the referenced entity is
to the entity that contains the embeddable instance(s) and not to the embeddable itself.[17] An
embeddable class that is used as an embedded id or as a map key must not contain such a relationship.
Additional requirements and restrictions on embeddable classes are described in Section 2.6.
[16] Direct or indirect circular containment dependencies among embeddable classes are not permitted.
[17] An entity cannot have a unidirectional relationship to the embeddable class of another entity (or itself).
4/2/13
40
JSR-338 Final Release
Oracle
Collections of Embeddable Classes and Basic TypesJava Persistence 2.1, Final Release
Entities
2.6 Collections of Embeddable Classes and Basic Types
A persistent field or property of an entity or embeddable class may correspond to a collection of a basic
type or embeddable class (“element collection”). Such a collection, when specified as such by the ElementCollection annotation, is mapped by means of a collection table, as defined in Section 11.1.8.
If the ElementCollection annotation (or XML equivalent) is not specified for the collection-valued field or property, the rules of Section 2.8 apply.
An embeddable class (including an embeddable class within another embeddable class) that is contained within an element collection must not contain an element collection, nor may it contain a relationship to an entity other than a many-to-one or one-to-one relationship. The embeddable class must be
on the owning side of such a relationship and the relationship must be mapped by a foreign key mapping. (See Section 2.9.)
2.7 Map Collections
Collections of elements and entity relationships can be represented as java.util.Map collections.
The map key and the map value independently can each be a basic type, an embeddable class, or an
entity.
The ElementCollection, OneToMany, and ManyToMany annotations are used to specify the
map as an element collection or entity relationship as follows: when the map value is a basic type or
embeddable class, the ElementCollection annotation is used; when the map value is an entity, the
OneToMany or ManyToMany annotation is used.
Bidirectional relationships represented as java.util.Map collections support the use of the Map
datatype on one side of the relationship only.
2.7.1 Map Keys
If the map key type is a basic type, the MapKeyColumn annotation can be used to specify the column
mapping for the map key. If the MapKeyColumn annotation is not specified, the default values of the
MapKeyColumn annotation apply as described in section 11.1.33.
If the map key type is an embeddable class, the mappings for the map key columns are defaulted
according to the default column mappings for the embeddable class. (See Section 11.1.9, “Column
Annotation”). The AttributeOverride and AttributeOverrides annotations can be used to
override these mappings, as described in sections 11.1.4 and 11.1.5. If an embeddable class is used as a
map key, the embeddable class must implement the hashCode and equals methods consistently
with the database columns to which the embeddable is mapped[18].
[18] Note that when an embeddable instance is used as a map key, these attributes represent its identity. Changes to embeddable
instances used as map keys have undefined behaviour and should be avoided.
JSR-338 Final Release
41
4/2/13
Oracle
Entities
Java Persistence 2.1, Final Release Mapping Defaults for Non-Relationship Fields or
If the map key type is an entity, the MapKeyJoinColumn and MapKeyJoinColumns annotations
are used to specify the column mappings for the map key. If the primary key of the referenced entity is
a simple primary key and the MapKeyJoinColumn annotation is not specified, the default values of
the MapKeyJoinColumn annotation apply as described in section 11.1.35.
If Java generic types are not used in the declaration of a relationship attribute of type
java.util.Map, the MapKeyClass annotation must be used to specify the type of the key of the
map.
The MapKey annotation is used to specify the special case where the map key is itself the primary key
or a persistent field or property of the entity that is the value of the map. The MapKeyClass annotation is not used when MapKey is specified.
2.7.2 Map Values
When the value type of the map is a basic type or an embeddable class, a collection table is used to map
the map. If Java generic types are not used, the targetClass element of the ElementCollection annotation must be used to specify the value type for the map. The default column mappings for
the map value are derived according to the default mapping rules for the CollectionTable annotation defined in section 11.1.8. The Column annotation is used to override these defaults for a map value
of basic type. The AttributeOverride(s) and AssociationOverride(s) annotations are
used to override the mappings for a map value that is an embeddable class.
When the value type of the map is an entity, a join table is used to map the map for a many-to-many
relationship or, by default, for a one-to-many unidirectional relationship. If the relationship is a bidirectional one-to-many/many-to-one relationship, by default the map is mapped in the table of the entity
that is the value of the map. If Java generic types are not used, the targetEntity element of the
OneToMany or ManyToMany annotation must be used to specify the value type for the map. Default
mappings are described in Section 2.10.
2.8 Mapping Defaults for Non-Relationship Fields or Properties
If a persistent field or property other than a relationship property is not annotated with one of the mapping annotations defined in Chapter 11 (or equivalent mapping information is not specified in the XML
descriptor), the following default mapping rules are applied in order:
• If the type is a class that is annotated with the Embeddable annotation, it is mapped in the
same way as if the field or property were annotated with the Embedded annotation. See Sections 11.1.15 and 11.1.16.
• If the type of the field or property is one of the following, it is mapped in the same way as it
would if it were annotated as Basic: Java primitive types, wrappers of the primitive types,
java.lang.String,
java.math.BigInteger,
java.math.BigDecimal,
java.util.Date, java.util.Calendar, java.sql.Date, java.sql.Time,
java.sql.Timestamp, byte[], Byte[], char[], Character[], enums, any other
type that implements Serializable. See Sections 11.1.6, 11.1.18, 11.1.28, and 11.1.51.
4/2/13
42
JSR-338 Final Release
Oracle
Entity Relationships
Java Persistence 2.1, Final Release
Entities
It is an error if no annotation is present and none of the above rules apply.
2.9 Entity Relationships
Relationships among entities may be one-to-one, one-to-many, many-to-one, or many-to-many. Relationships are polymorphic.
If there is an association between two entities, one of the following relationship modeling annotations
must be applied to the corresponding persistent property or field of the referencing entity: OneToOne,
OneToMany, ManyToOne, ManyToMany. For associations that do not specify the target type (e.g.,
where Java generic types are not used for collections), it is necessary to specify the entity that is the target of the relationship.[19] Equivalent XML elements may be used as an alternative to these mapping
annotations.
These annotations mirror common practice in relational database schema modeling. The use of the
relationship modeling annotations allows the object/relationship mapping of associations to the relational database schema to be fully defaulted, to provide an ease-of-development facility. This is
described in Section 2.10, “Relationship Mapping Defaults”.
Relationships may be bidirectional or unidirectional. A bidirectional relationship has both an owning
side and an inverse (non-owning) side. A unidirectional relationship has only an owning side. The owning side of a relationship determines the updates to the relationship in the database, as described in section 3.2.4.
The following rules apply to bidirectional relationships:
• The inverse side of a bidirectional relationship must refer to its owning side by use of the
mappedBy element of the OneToOne, OneToMany, or ManyToMany annotation. The
mappedBy element designates the property or field in the entity that is the owner of the relationship.
• The many side of one-to-many / many-to-one bidirectional relationships must be the owning
side, hence the mappedBy element cannot be specified on the ManyToOne annotation.
• For one-to-one bidirectional relationships, the owning side corresponds to the side that contains the corresponding foreign key.
• For many-to-many bidirectional relationships either side may be the owning side.
The relationship modeling annotation constrains the use of the cascade=REMOVE specification. The
cascade=REMOVE specification should only be applied to associations that are specified as OneToOne or OneToMany. Applications that apply cascade=REMOVE to other associations are not portable.
[19] For associations of type java.util.Map, target type refers to the type that is the Map value.
JSR-338 Final Release
43
4/2/13
Oracle
Entities
Java Persistence 2.1, Final Release
Entity Relationships
Associations that are specified as OneToOne or OneToMany support use of the orphanRemoval
option. The following behaviors apply when orphanRemoval is in effect:
• If an entity that is the target of the relationship is removed from the relationship (by setting the
relationship to null or removing the entity from the relationship collection), the remove operation will be applied to the entity being orphaned. The remove operation is applied at the time of
the flush operation. The orphanRemoval functionality is intended for entities that are privately “owned” by their parent entity. Portable applications must otherwise not depend upon a
specific order of removal, and must not reassign an entity that has been orphaned to another
relationship or otherwise attempt to persist it. If the entity being orphaned is a detached, new,
or removed entity, the semantics of orphanRemoval do not apply.
• If the remove operation is applied to a managed source entity, the remove operation will be
cascaded to the relationship target in accordance with the rules of section 3.2.3, (and hence it is
not necessary to specify cascade=REMOVE for the relationship)[20].
Section 2.10, “Relationship Mapping Defaults”, defines relationship mapping defaults for entity relationships. Additional mapping annotations (e.g., column and table mapping annotations) may be specified to override or further refine the default mappings and mapping strategies described in Section 2.10.
In addition, this specification also requires support for the following alternative mapping strategies:
• The mapping of unidirectional one-to-many relationships by means of foreign key mappings.
The JoinColumn annotation or corresponding XML element must be used to specify such
non-default mappings. See section 11.1.25.
• The mapping of unidirectional and bidirectional one-to-one relationships, bidirectional
many-to-one/one-to-many relationships, and unidirectional many-to-one relationships by
means of join table mappings. The JoinTable annotation or corresponding XML element
must be used to specify such non-default mappings. See section 11.1.27.
Such mapping annotations must be specified on the owning side of the relationship. Any overriding of
mapping defaults must be consistent with the relationship modeling annotation that is specified. For
example, if a many-to-one relationship mapping is specified, it is not permitted to specify a unique key
constraint on the foreign key for the relationship.
The persistence provider handles the object/relational mapping of the relationships, including their
loading and storing to the database as specified in the metadata of the entity class, and the referential
integrity of the relationships as specified in the database (e.g., by foreign key constraints).
Note that it is the application that bears responsibility for maintaining the consistency of runtime relationships—for example, for insuring that the “one” and the “many” sides of a bidirectional relationship are consistent with one another when the application updates the
relationship at runtime.
[20] If the parent is detached or new or was previously removed before the orphan was associated with it, the remove operation is not
applied to the entity being orphaned.
4/2/13
44
JSR-338 Final Release
Oracle
Relationship Mapping Defaults
Java Persistence 2.1, Final Release
Entities
If there are no associated entities for a multi-valued relationship of an entity fetched from the database,
the persistence provider is responsible for returning an empty collection as the value of the relationship.
2.10 Relationship Mapping Defaults
This section defines the mapping defaults that apply to the use of the OneToOne, OneToMany,
ManyToOne, and ManyToMany relationship modeling annotations. The same mapping defaults apply
when the XML descriptor is used to denote the relationship cardinalities.
2.10.1 Bidirectional OneToOne Relationships
Assuming that:
Entity A references a single instance of Entity B.
Entity B references a single instance of Entity A.
Entity A is specified as the owner of the relationship.
The following mapping defaults apply:
Entity A is mapped to a table named A.
Entity B is mapped to a table named B.
Table A contains a foreign key to table B. The foreign key column name is formed as the concatenation of the following: the name of the relationship property or field of entity A; "_"; the
name of the primary key column in table B. The foreign key column has the same type as the
primary key of table B and there is a unique key constraint on it.
Example:
@Entity
public class Employee {
private Cubicle assignedCubicle;
}
JSR-338 Final Release
@OneToOne
public Cubicle getAssignedCubicle() {
return assignedCubicle;
}
public void setAssignedCubicle(Cubicle cubicle) {
this.assignedCubicle = cubicle;
}
...
45
4/2/13
Oracle
Entities
Java Persistence 2.1, Final Release
Relationship Mapping Defaults
@Entity
public class Cubicle {
private Employee residentEmployee;
}
@OneToOne(mappedBy="assignedCubicle")
public Employee getResidentEmployee() {
return residentEmployee;
}
public void setResidentEmployee(Employee employee) {
this.residentEmployee = employee;
}
...
In this example:
Entity Employee references a single instance of Entity Cubicle.
Entity Cubicle references a single instance of Entity Employee.
Entity Employee is the owner of the relationship.
The following mapping defaults apply:
Entity Employee is mapped to a table named EMPLOYEE.
Entity Cubicle is mapped to a table named CUBICLE.
Table EMPLOYEE contains a foreign key to table CUBICLE. The foreign key column is named
ASSIGNEDCUBICLE_<PK of CUBICLE>, where <PK of CUBICLE> denotes the name of
the primary key column of table CUBICLE. The foreign key column has the same type as the
primary key of CUBICLE, and there is a unique key constraint on it.
2.10.2 Bidirectional ManyToOne / OneToMany Relationships
Assuming that:
Entity A references a single instance of Entity B.
Entity B references a collection of Entity A[21].
Entity A must be the owner of the relationship.
The following mapping defaults apply:
Entity A is mapped to a table named A.
Entity B is mapped to a table named B.
Table A contains a foreign key to table B. The foreign key column name is formed as the concatenation of the following: the name of the relationship property or field of entity A; "_"; the
[21] When the relationship is modeled as a java.util.Map, “Entity B references a collection of Entity A” means that Entity B references a map collection in which the type of the Map value is Entity A. The map key may be a basic type, embeddable class, or
an entity.
4/2/13
46
JSR-338 Final Release
Oracle
Relationship Mapping Defaults
Java Persistence 2.1, Final Release
Entities
name of the primary key column in table B. The foreign key column has the same type as the
primary key of table B.
Example:
@Entity
public class Employee {
private Department department;
}
@ManyToOne
public Department getDepartment() {
return department;
}
public void setDepartment(Department department) {
this.department = department;
}
...
@Entity
public class Department {
private Collection<Employee> employees = new HashSet();
@OneToMany(mappedBy="department")
public Collection<Employee> getEmployees() {
return employees;
}
}
public void setEmployees(Collection<Employee> employees) {
this.employees = employees;
}
...
In this example:
Entity Employee references a single instance of Entity Department.
Entity Department references a collection of Entity Employee.
Entity Employee is the owner of the relationship.
The following mapping defaults apply:
Entity Employee is mapped to a table named EMPLOYEE.
Entity Department is mapped to a table named DEPARTMENT.
Table EMPLOYEE contains a foreign key to table DEPARTMENT. The foreign key column is
named DEPARTMENT_<PK of DEPARTMENT>, where <PK of DEPARTMENT> denotes
the name of the primary key column of table DEPARTMENT. The foreign key column has the
same type as the primary key of DEPARTMENT.
JSR-338 Final Release
47
4/2/13
Oracle
Entities
Java Persistence 2.1, Final Release
Relationship Mapping Defaults
2.10.3 Unidirectional Single-Valued Relationships
Assuming that:
Entity A references a single instance of Entity B.
Entity B does not reference Entity A.
A unidirectional relationship has only an owning side, which in this case must be Entity A.
The unidirectional single-valued relationship modeling case can be specified as either a unidirectional
OneToOne or as a unidirectional ManyToOne relationship.
2.10.3.1 Unidirectional OneToOne Relationships
The following mapping defaults apply:
Entity A is mapped to a table named A.
Entity B is mapped to a table named B.
Table A contains a foreign key to table B. The foreign key column name is formed as the concatenation of the following: the name of the relationship property or field of entity A; "_"; the
name of the primary key column in table B. The foreign key column has the same type as the
primary key of table B and there is a unique key constraint on it.
Example:
@Entity
public class Employee {
private TravelProfile profile;
}
@OneToOne
public TravelProfile getProfile() {
return profile;
}
public void setProfile(TravelProfile profile) {
this.profile = profile;
}
...
@Entity
public class TravelProfile {
...
}
In this example:
Entity Employee references a single instance of Entity TravelProfile.
Entity TravelProfile does not reference Entity Employee.
Entity Employee is the owner of the relationship.
4/2/13
48
JSR-338 Final Release
Oracle
Relationship Mapping Defaults
Java Persistence 2.1, Final Release
Entities
The following mapping defaults apply:
Entity Employee is mapped to a table named EMPLOYEE.
Entity TravelProfile is mapped to a table named TRAVELPROFILE.
Table EMPLOYEE contains a foreign key to table TRAVELPROFILE. The foreign key column
is named PROFILE_<PK of TRAVELPROFILE>, where <PK of TRAVELPROFILE>
denotes the name of the primary key column of table TRAVELPROFILE. The foreign key column has the same type as the primary key of TRAVELPROFILE, and there is a unique key
constraint on it.
2.10.3.2 Unidirectional ManyToOne Relationships
The following mapping defaults apply:
Entity A is mapped to a table named A.
Entity B is mapped to a table named B.
Table A contains a foreign key to table B. The foreign key column name is formed as the concatenation of the following: the name of the relationship property or field of entity A; "_"; the
name of the primary key column in table B. The foreign key column has the same type as the
primary key of table B.
Example:
@Entity
public class Employee {
private Address address;
}
@ManyToOne
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
...
@Entity
public class Address {
...
}
In this example:
Entity Employee references a single instance of Entity Address.
Entity Address does not reference Entity Employee.
Entity Employee is the owner of the relationship.
JSR-338 Final Release
49
4/2/13
Oracle
Entities
Java Persistence 2.1, Final Release
Relationship Mapping Defaults
The following mapping defaults apply:
Entity Employee is mapped to a table named EMPLOYEE.
Entity Address is mapped to a table named ADDRESS.
Table EMPLOYEE contains a foreign key to table ADDRESS. The foreign key column is named
ADDRESS_<PK of ADDRESS>, where <PK of ADDRESS> denotes the name of the primary
key column of table ADDRESS. The foreign key column has the same type as the primary key
of ADDRESS.
2.10.4 Bidirectional ManyToMany Relationships
Assuming that:
Entity A references a collection of Entity B.
Entity B references a collection of Entity A.
Entity A is the owner of the relationship.
The following mapping defaults apply:
Entity A is mapped to a table named A.
Entity B is mapped to a table named B.
There is a join table that is named A_B (owner name first). This join table has two foreign key
columns. One foreign key column refers to table A and has the same type as the primary key of
table A. The name of this foreign key column is formed as the concatenation of the following:
the name of the relationship property or field of entity B; "_"; the name of the primary key column in table A. The other foreign key column refers to table B and has the same type as the primary key of table B. The name of this foreign key column is formed as the concatenation of the
following: the name of the relationship property or field of entity A; "_"; the name of the primary key column in table B.
Example:
@Entity
public class Project {
private Collection<Employee> employees;
@ManyToMany
public Collection<Employee> getEmployees() {
return employees;
}
}
4/2/13
public void setEmployees(Collection<Employee> employees) {
this.employees = employees;
}
...
50
JSR-338 Final Release
Oracle
Relationship Mapping Defaults
Java Persistence 2.1, Final Release
Entities
@Entity
public class Employee {
private Collection<Project> projects;
@ManyToMany(mappedBy="employees")
public Collection<Project> getProjects() {
return projects;
}
}
public void setProjects(Collection<Project> projects) {
this.projects = projects;
}
...
In this example:
Entity Project references a collection of Entity Employee.
Entity Employee references a collection of Entity Project.
Entity Project is the owner of the relationship.
The following mapping defaults apply:
Entity Project is mapped to a table named PROJECT.
Entity Employee is mapped to a table named EMPLOYEE.
There is a join table that is named PROJECT_EMPLOYEE (owner name first). This join table
has two foreign key columns. One foreign key column refers to table PROJECT and has the
same type as the primary key of PROJECT. The name of this foreign key column is
PROJECTS_<PK of PROJECT>, where <PK of PROJECT> denotes the name of the primary
key column of table PROJECT. The other foreign key column refers to table EMPLOYEE and
has the same type as the primary key of EMPLOYEE. The name of this foreign key column is
EMPLOYEES_<PK of EMPLOYEE>, where <PK of EMPLOYEE> denotes the name of the
primary key column of table EMPLOYEE.
2.10.5 Unidirectional Multi-Valued Relationships
Assuming that:
Entity A references a collection of Entity B.
Entity B does not reference Entity A.
A unidirectional relationship has only an owning side, which in this case must be Entity A.
The unidirectional multi-valued relationship modeling case can be specified as either a unidirectional
OneToMany or as a unidirectional ManyToMany relationship.
JSR-338 Final Release
51
4/2/13
Oracle
Entities
Java Persistence 2.1, Final Release
Relationship Mapping Defaults
2.10.5.1 Unidirectional OneToMany Relationships
The following mapping defaults apply:
Entity A is mapped to a table named A.
Entity B is mapped to a table named B.
There is a join table that is named A_B (owner name first). This join table has two foreign key
columns. One foreign key column refers to table A and has the same type as the primary key of
table A. The name of this foreign key column is formed as the concatenation of the following:
the name of entity A; "_"; the name of the primary key column in table A. The other foreign
key column refers to table B and has the same type as the primary key of table B and there is a
unique key constraint on it. The name of this foreign key column is formed as the concatenation of the following: the name of the relationship property or field of entity A; "_"; the name
of the primary key column in table B.
Example:
@Entity
public class Employee {
private Collection<AnnualReview> annualReviews;
@OneToMany
public Collection<AnnualReview> getAnnualReviews() {
return annualReviews;
}
public void setAnnualReviews(Collection<AnnualReview> annualReviews) {
this.annualReviews = annualReviews;
}
...
}
@Entity
public class AnnualReview {
...
}
In this example:
Entity Employee references a collection of Entity AnnualReview.
Entity AnnualReview does not reference Entity Employee.
Entity Employee is the owner of the relationship.
The following mapping defaults apply:
Entity Employee is mapped to a table named EMPLOYEE.
Entity AnnualReview is mapped to a table named ANNUALREVIEW.
There is a join table that is named EMPLOYEE_ANNUALREVIEW (owner name first). This
join table has two foreign key columns. One foreign key column refers to table EMPLOYEE
4/2/13
52
JSR-338 Final Release
Oracle
Relationship Mapping Defaults
Java Persistence 2.1, Final Release
Entities
and has the same type as the primary key of EMPLOYEE. This foreign key column is named
EMPLOYEE_<PK of EMPLOYEE>, where <PK of EMPLOYEE> denotes the name of the
primary key column of table EMPLOYEE. The other foreign key column refers to table ANNUALREVIEW and has the same type as the primary key of ANNUALREVIEW. This foreign key
column is named ANNUALREVIEWS_<PK of ANNUALREVIEW>, where <PK of ANNUALREVIEW> denotes the name of the primary key column of table ANNUALREVIEW. There
is a unique key constraint on the foreign key that refers to table ANNUALREVIEW.
2.10.5.2 Unidirectional ManyToMany Relationships
The following mapping defaults apply:
Entity A is mapped to a table named A.
Entity B is mapped to a table named B.
There is a join table that is named A_B (owner name first). This join table has two foreign key
columns. One foreign key column refers to table A and has the same type as the primary key of
table A. The name of this foreign key column is formed as the concatenation of the following:
the name of entity A; "_"; the name of the primary key column in table A. The other foreign
key column refers to table B and has the same type as the primary key of table B. The name of
this foreign key column is formed as the concatenation of the following: the name of the relationship property or field of entity A; "_"; the name of the primary key column in table B.
Example:
@Entity
public class Employee {
private Collection<Patent> patents;
@ManyToMany
public Collection<Patent> getPatents() {
return patents;
}
}
public void setPatents(Collection<Patent> patents) {
this.patents = patents;
}
...
@Entity
public class Patent {
...
}
In this example:
Entity Employee references a collection of Entity Patent.
Entity Patent does not reference Entity Employee.
Entity Employee is the owner of the relationship.
JSR-338 Final Release
53
4/2/13
Oracle
Entities
Java Persistence 2.1, Final Release
Inheritance
The following mapping defaults apply:
Entity Employee is mapped to a table named EMPLOYEE.
Entity Patent is mapped to a table named PATENT.
There is a join table that is named EMPLOYEE_PATENT (owner name first). This join table
has two foreign key columns. One foreign key column refers to table EMPLOYEE and has the
same type as the primary key of EMPLOYEE. This foreign key column is named
EMPLOYEE_<PK of EMPLOYEE>, where <PK of EMPLOYEE> denotes the name of the
primary key column of table EMPLOYEE. The other foreign key column refers to table
PATENT and has the same type as the primary key of PATENT. This foreign key column is
named PATENTS_<PK of PATENT>, where <PK of PATENT> denotes the name of the primary key column of table PATENT.
2.11 Inheritance
An entity may inherit from another entity class. Entities support inheritance, polymorphic associations,
and polymorphic queries.
Both abstract and concrete classes can be entities. Both abstract and concrete classes can be annotated
with the Entity annotation, mapped as entities, and queried for as entities.
Entities can extend non-entity classes and non-entity classes can extend entity classes.
These concepts are described further in the following sections.
2.11.1 Abstract Entity Classes
An abstract class can be specified as an entity. An abstract entity differs from a concrete entity only in
that it cannot be directly instantiated. An abstract entity is mapped as an entity and can be the target of
queries (which will operate over and/or retrieve instances of its concrete subclasses).
An abstract entity class is annotated with the Entity annotation or denoted in the XML descriptor as
an entity.
The following example shows the use of an abstract entity class in the entity inheritance hierarchy.
Example: Abstract class as an Entity
@Entity
@Table(name="EMP")
@Inheritance(strategy=JOINED)
public abstract class Employee {
@Id protected Integer empId;
@Version protected Integer version;
@ManyToOne protected Address address;
...
}
4/2/13
54
JSR-338 Final Release
Oracle
Inheritance
Java Persistence 2.1, Final Release
Entities
@Entity
@Table(name="FT_EMP")
@DiscriminatorValue("FT")
@PrimaryKeyJoinColumn(name="FT_EMPID")
public class FullTimeEmployee extends Employee {
// Inherit empId, but mapped in this class to FT_EMP.FT_EMPID
// Inherit version mapped to EMP.VERSION
// Inherit address mapped to EMP.ADDRESS fk
}
// Defaults to FT_EMP.SALARY
protected Integer salary;
...
@Entity
@Table(name="PT_EMP")
@DiscriminatorValue("PT")
// PK column is PT_EMP.EMPID due to PrimaryKeyJoinColumn default
public class PartTimeEmployee extends Employee {
protected Float hourlyWage;
...
}
2.11.2 Mapped Superclasses
An entity may inherit from a superclass that provides persistent entity state and mapping information,
but which is not itself an entity. Typically, the purpose of such a mapped superclass is to define state
and mapping information that is common to multiple entity classes.
A mapped superclass, unlike an entity, is not queryable and must not be passed as an argument to
EntityManager or Query operations. Persistent relationships defined by a mapped superclass must
be unidirectional.
Both abstract and concrete classes may be specified as mapped superclasses. The MappedSuperclass annotation (or mapped-superclass XML descriptor element) is used to designate a
mapped superclass.
A class designated as a mapped superclass has no separate table defined for it. Its mapping information
is applied to the entities that inherit from it.
A class designated as a mapped superclass can be mapped in the same way as an entity except that the
mappings will apply only to its subclasses since no table exists for the mapped superclass itself. When
applied to the subclasses, the inherited mappings will apply in the context of the subclass tables. Mapping information can be overridden in such subclasses by using the AttributeOverride and
AssociationOverride annotations or corresponding XML elements.
All other entity mapping defaults apply equally to a class designated as a mapped superclass.
The following example illustrates the definition of a concrete class as a mapped superclass.
JSR-338 Final Release
55
4/2/13
Oracle
Entities
Java Persistence 2.1, Final Release
Inheritance
Example: Concrete class as a mapped superclass
@MappedSuperclass
public class Employee {
@Id protected Integer empId;
@Version protected Integer version;
@ManyToOne @JoinColumn(name="ADDR")
protected Address address;
}
public
public
public
public
Integer getEmpId() { ... }
void setEmpId(Integer id) { ... }
Address getAddress() { ... }
void setAddress(Address addr) { ... }
// Default table is FTEMPLOYEE table
@Entity
public class FTEmployee extends Employee {
// Inherited empId field mapped to FTEMPLOYEE.EMPID
// Inherited version field mapped to FTEMPLOYEE.VERSION
// Inherited address field mapped to FTEMPLOYEE.ADDR fk
// Defaults to FTEMPLOYEE.SALARY
protected Integer salary;
public FTEmployee() {}
}
public Integer getSalary() { ... }
public void setSalary(Integer salary) { ... }
@Entity
@Table(name="PT_EMP")
@AssociationOverride(name="address",
[email protected](name="ADDR_ID"))
public class PartTimeEmployee extends Employee {
// Inherited empId field mapped to PT_EMP.EMPID
// Inherited version field mapped to PT_EMP.VERSION
// address field mapping overridden to PT_EMP.ADDR_ID fk
@Column(name="WAGE")
protected Float hourlyWage;
public PartTimeEmployee() {}
}
4/2/13
public Float getHourlyWage() { ... }
public void setHourlyWage(Float wage) { ... }
56
JSR-338 Final Release
Oracle
Inheritance
Java Persistence 2.1, Final Release
Entities
2.11.3 Non-Entity Classes in the Entity Inheritance Hierarchy
An entity can have a non-entity superclass, which may be either a concrete or abstract class.[22]
The non-entity superclass serves for inheritance of behavior only. The state of a non-entity superclass is
not persistent. Any state inherited from non-entity superclasses is non-persistent in an inheriting entity
class. This non-persistent state is not managed by the entity manager[23]. Any annotations on such
superclasses are ignored.
Non-entity classes cannot be passed as arguments to methods of the EntityManager or Query
interfaces[24] and cannot bear mapping information.
The following example illustrates the use of a non-entity class as a superclass of an entity.
Example: Non-entity superclass
public class Cart {
protected Integer operationCount; // transient state
public Cart() { operationCount = 0; }
public Integer getOperationCount() { return operationCount; }
public void incrementOperationCount() { operationCount++; }
}
@Entity
public class ShoppingCart extends Cart {
Collection<Item> items = new Vector<Item>();
public ShoppingCart() { super(); }
...
@OneToMany
public Collection<Item> getItems() { return items; }
}
public void addItem(Item item) {
items.add(item);
incrementOperationCount();
}
[22] The superclass must not be an embeddable class or id class.
[23] If a transaction-scoped persistence context is used, it is not required to be retained across transactions.
[24] This includes instances of a non-entity class that extends an entity class.
JSR-338 Final Release
57
4/2/13
Oracle
Entities
Java Persistence 2.1, Final Release
Inheritance Mapping Strategies
2.12 Inheritance Mapping Strategies
The mapping of class hierarchies is specified through metadata.
There are three basic strategies that are used when mapping a class or class hierarchy to a relational
database:
• a single table per class hierarchy
• a joined subclass strategy, in which fields that are specific to a subclass are mapped to a sepa-
rate table than the fields that are common to the parent class, and a join is performed to instantiate the subclass.
• a table per concrete entity class
An implementation is required to support the single table per class hierarchy inheritance mapping strategy and the joined subclass strategy.
Support for the table per concrete class inheritance mapping strategy is optional in this
release. Applications that use this mapping strategy will not be portable.
Support for the combination of inheritance strategies within a single entity inheritance hierarchy is not required by this specification.
2.12.1 Single Table per Class Hierarchy Strategy
In this strategy, all the classes in a hierarchy are mapped to a single table. The table has a column that
serves as a “discriminator column”, that is, a column whose value identifies the specific subclass to
which the instance that is represented by the row belongs.
This mapping strategy provides good support for polymorphic relationships between entities and for
queries that range over the class hierarchy.
It has the drawback, however, that it requires that the columns that correspond to state specific to the
subclasses be nullable.
2.12.2 Joined Subclass Strategy
In the joined subclass strategy, the root of the class hierarchy is represented by a single table. Each subclass is represented by a separate table that contains those fields that are specific to the subclass (not
inherited from its superclass), as well as the column(s) that represent its primary key. The primary key
column(s) of the subclass table serves as a foreign key to the primary key of the superclass table.
This strategy provides support for polymorphic relationships between entities.
It has the drawback that it requires that one or more join operations be performed to instantiate instances
of a subclass. In deep class hierarchies, this may lead to unacceptable performance. Queries that range
over the class hierarchy likewise require joins.
4/2/13
58
JSR-338 Final Release
Oracle
Naming of Database Objects
Java Persistence 2.1, Final Release
Entities
2.12.3 Table per Concrete Class Strategy
In this mapping strategy, each class is mapped to a separate table. All properties of the class, including
inherited properties, are mapped to columns of the table for the class.
This strategy has the following drawbacks:
• It provides poor support for polymorphic relationships.
• It typically requires that SQL UNION queries (or a separate SQL query per subclass) be issued
for queries that are intended to range over the class hierarchy.
2.13 Naming of Database Objects
Many annotations and annotation elements contain names of database objects or assume default names
for database objects.
This specification requires the following with regard to the interpretation of the names referencing database objects. These names include the names of tables, columns, and other database elements. Such
names also include names that result from defaulting (e.g., a table name that is defaulted from an entity
name or a column name that is defaulted from a field or property name).
By default, the names of database objects must be treated as undelimited identifiers and passed to the
database as such.
For example, assuming the use of an English locale, the following must be passed to the database as
undelimited identifers so that they will be treated as equivalent for all databases that comply with the
SQL Standard’s requirements for the treatment of “regular identifiers” (undelimited identifiers) and
“delimited identifiers” [4]:
@Table(name="Customer")
@Table(name="customer")
@Table(name="cUsTomer")
Similarly, the following must be treated as equivalent:
@JoinColumn(name="CUSTOMER")
@ManyToOne Customer customer;
@JoinColumn(name="customer")
@ManyToOne Customer customer;
@ManyToOne Customer customer;
JSR-338 Final Release
59
4/2/13
Oracle
Entities
Java Persistence 2.1, Final Release
Naming of Database Objects
To specify delimited identifiers, one of the following approaches must be used:
• It is possible to specify that all database identifiers in use for a persistence unit be treated as
delimited identifiers by specifying the <delimited-identifiers/> element within the
persistence-unit-defaults element of the object/relational xml mapping file. If the
<delimited-identifiers/> element is specified, it cannot be overridden.
• It is possible to specify on a per-name basis that a name for a database object is to be interpreted as a delimited identifier as follows:
• Using annotations, a name is specified as a delimited identifier by enclosing the name
within double quotes, whereby the
@Table(name="\"customer\"").
inner
quotes
are
escaped,
e.g.,
• When using XML, a name is specified as a delimited identifier by use of double
quotes, e.g., <table name="&quot;customer&quot;"/>[25]
The following annotations contain elements whose values correspond to names of database identifiers
and for which the above rules apply, including when their use is nested within that of other annotations:
EntityResult (discriminatorColumn element)
FieldResult (column element)
ColumnResult (name element)
CollectionTable (name, catalog, schema elements)
Column (name, columnDefinition, table elements)
DiscriminatorColumn (name, columnDefinition elements)
ForeignKey (name, foreignKeyDefinition elements)
Index (name, columnList elements)
JoinColumn (name, referencedColumnName, columnDefinition, table elements)
JoinTable (name, catalog, schema elements)
MapKeyColumn (name, columnDefinition, table elements)
MapKeyJoinColumn
table elements)
(name,
referencedColumnName,
columnDefinition,
NamedStoredProcedureQuery (procedureName element)
OrderColumn (name, columnDefinition elements)
PrimaryKeyJoinColumn (name, referencedColumnName, columnDefinition
elements)
SecondaryTable (name, catalog, schema elements)
SequenceGenerator (sequenceName, catalog, schema elements)
StoredProcedureParameter (name element)
Table (name, catalog, schema elements)
[25] If <delimited-identifiers> is specified and individual annotations or XML elements or attributes use escaped double quotes, the
double-quotes appear in the name of the database identifier.
4/2/13
60
JSR-338 Final Release
Oracle
Naming of Database Objects
Java Persistence 2.1, Final Release
Entities
TableGenerator (table, catalog, schema, pkColumnName, valueColumnName elements)
UniqueConstraint (name, columnNames elements)
The following XML elements and types contain elements or attributes whose values correspond to
names of database identifiers and for which the above rules apply:
entity-mappings (schema, catalog elements)
persistence-unit-defaults (schema, catalog elements)
collection-table (name, catalog, schema attributes)
column (name, table, column-definition attributes)
column-result (name attribute)
discriminator-column (name, column-definition attributes)
entity-result (discriminator-column attribute)
field-result (column attribute)
foreign-key (name, foreign-key-definition attributes)
index (name attribute, column-list element)
join-column (name, referenced-column-name, column-definition, table
attributes)
join-table (name, catalog, schema attributes)
map-key-column (name, column-definition, table attributes)
map-key-join-column (name, referenced-column-name, column-definition, table attributes)
named-stored-procedure-query (procedure-name attribute)
order-column (name, column-definition attributes)
primary-key-join-column (name, referenced-column-name, column-definition attributes)
secondary-table (name, catalog, schema attributes)
sequence-generator (sequence-name, catalog, schema attributes)
stored-procedure-parameter (name attribute)
table (name, catalog, schema attributes)
table-generator (table, catalog, schema, pk-column-name, value-column-name attributes)
unique-constraint (name attribute, column-name element)
JSR-338 Final Release
61
4/2/13
Oracle
Entities
Java Persistence 2.1, Final Release
4/2/13
62
Naming of Database Objects
JSR-338 Final Release
Oracle
EntityManager
Ch apt er 3
Java Persistence 2.1, Final Release
Entity Operations
Entity Operations
This chapter describes the use of the EntityManager API to manage the entity instance lifecycle and
the use of the Query API to retrieve and query entities and their persistent state.
3.1 EntityManager
An EntityManager instance is associated with a persistence context. A persistence context is a set of
entity instances in which for any persistent entity identity there is a unique entity instance. Within the
persistence context, the entity instances and their lifecycle are managed. The EntityManager interface defines the methods that are used to interact with the persistence context. The EntityManager
API is used to create and remove persistent entity instances, to find persistent entities by primary key,
and to query over persistent entities.
The set of entities that can be managed by a given EntityManager instance is defined by a persistence unit. A persistence unit defines the set of all classes that are related or grouped by the application,
and which must be colocated in their mapping to a single database.
JSR-338 Final Release
63
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
EntityManager
Section 3.1 defines the EntityManager interface. The entity instance lifecycle is described in Section 3.2. The relationships between entity managers and persistence contexts are described in section
3.3 and in further detail in Chapter 7. Section 3.4 describes mechanisms for concurrency control and
locking. Section 3.5 describes entity listeners and lifecycle callback methods for entities. Section 3.6
describes support for automatic use of Bean Validation. Section 3.7 describes the use of entity graphs to
control the path and boundaries of find and query operations. Section 3.8 describes mechanisms for
defining conversions between entity and database representations for attributes of basic types. Section
3.9 describes mechanisms for portable second-level cache configuration. The Query, TypedQuery,
StoredProcedureQuery, and related interfaces are described in Section 3.10. Section 3.11 provides a summary of exceptions. The Java Persistence query language is defined in Chapter 4 and the
APIs for the construction of Criteria queries in Chapter 6. The definition of persistence units is
described in Chapter 8.
4/2/13
64
JSR-338 Final Release
Oracle
EntityManager
Java Persistence 2.1, Final Release
Entity Operations
3.1.1 EntityManager Interface
package javax.persistence;
import
import
import
import
import
import
import
java.util.Map;
java.util.List;
javax.persistence.metamodel.Metamodel;
javax.persistence.criteria.CriteriaBuilder;
javax.persistence.criteria.CriteriaQuery;
javax.persistence.criteria.CriteriaUpdate;
javax.persistence.criteria.CriteriaDelete;
/**
* Interface used to interact with the persistence context and to
* create executable query objects.
*/
public interface EntityManager {
/**
* Make an instance managed and persistent.
* @param entity
* @throws EntityExistsException if the entity already exists.
* (If the entity already exists, the EntityExistsException may
* be thrown when the persist operation is invoked, or the
* EntityExistsException or another PersistenceException may be
* thrown at flush or commit time.)
* @throws IllegalArgumentException if the instance is not an
*
entity
* @throws TransactionRequiredException if there is no
*
transaction when invoked on a container-managed
*
entity manager that is of type
*
PersistenceContextType.TRANSACTION.
*/
public void persist(Object entity);
/**
* Merge the state of the given entity into the
* current persistence context.
* @param entity
* @return the managed instance that the state was merged to
* @throws IllegalArgumentException if instance is not an
*
entity or is a removed entity
* @throws TransactionRequiredException if there is no
*
transaction when invoked on a container-managed
*
entity manager that is of type
*
PersistenceContextType.TRANSACTION.
*/
public <T> T merge(T entity);
/**
* Remove the entity instance.
* @param entity
* @throws IllegalArgumentException if the instance is not an
*
entity or is a detached entity
* @throws TransactionRequiredException if there is no
*
transaction when invoked on a container-managed
*
entity manager that is of type
*
PersistenceContextType.TRANSACTION.
*/
public void remove(Object entity);
JSR-338 Final Release
65
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
EntityManager
/**
* Find by primary key.
* Search for an entity of the specified class and primary key.
* If the entity instance is contained in the persistence context
* it is returned from there.
* @param entityClass
* @param primaryKey
* @return the found entity instance or null if the entity does
*
not exist
* @throws IllegalArgumentException if the first argument does
*
not denote an entity type or the second argument is
*
is not a valid type for that entity’s primary key or
*
is null
*/
public <T> T find(Class<T> entityClass, Object primaryKey);
/**
* Find by primary key, using the specified properties.
* Search for an entity of the specified class and primary key.
* If the entity instance is contained in the persistence context
* it is returned from there.
* If a vendor-specific property or hint is not recognized,
* it is silently ignored.
* @param entityClass
* @param primaryKey
* @param properties standard and vendor-specific properties
*
and hints
* @return the found entity instance or null if the entity does
*
not exist
* @throws IllegalArgumentException if the first argument does
*
not denote an entity type or the second argument is
*
is not a valid type for that entity’s primary key or
*
is null
*/
public <T> T find(Class<T> entityClass,
Object primaryKey,
Map<String, Object> properties);
/**
* Find by primary key and lock.
* Search for an entity of the specified class and primary key
* and lock it with respect to the specified lock type.
* If the entity instance is contained in the persistence context
* it is returned from there, and the effect of this method is
* the same as if the lock method had been called on the entity.
* If the entity is found within the persistence context and the
* lock mode type is pessimistic and the entity has a version
* attribute, the persistence provider must perform optimistic
* version checks when obtaining the database lock. If these
* checks fail, the OptimisticLockException will be thrown.
* If the lock mode type is pessimistic and the entity instance
* is found but cannot be locked:
* - the PessimisticLockException will be thrown if the database
*
locking failure causes transaction-level rollback
* - the LockTimeoutException will be thrown if the database
*
locking failure causes only statement-level rollback
* @param entityClass
* @param primaryKey
4/2/13
66
JSR-338 Final Release
Oracle
EntityManager
Java Persistence 2.1, Final Release
Entity Operations
* @param lockMode
* @return the found entity instance or null if the entity does
*
not exist
* @throws IllegalArgumentException if the first argument does
*
not denote an entity type or the second argument is
*
not a valid type for that entity's primary key or
*
is null
* @throws TransactionRequiredException if there is no
*
transaction and a lock mode other than NONE is
*
specified or if invoked on an entity manager which has
*
not been joined to the current transaction and a lock
*
mode other than NONE is specified
* @throws OptimisticLockException if the optimistic version
*
check fails
* @throws PessimisticLockException if pessimistic locking
*
fails and the transaction is rolled back
* @throws LockTimeoutException if pessimistic locking fails and
*
only the statement is rolled back
* @throws PersistenceException if an unsupported lock call
*
is made
*/
public <T> T find(Class<T> entityClass,
Object primaryKey,
LockModeType lockMode);
/**
* Find by primary key and lock, using the specified properties.
* Search for an entity of the specified class and primary key
* and lock it with respect to the specified lock type.
* If the entity instance is contained in the persistence context
* it is returned from there. If the entity is found
* within the persistence context and the lock mode type
* is pessimistic and the entity has a version attribute, the
* persistence provider must perform optimistic version checks
* when obtaining the database lock. If these checks fail,
* the OptimisticLockException will be thrown.
* If the lock mode type is pessimistic and the entity instance
* is found but cannot be locked:
* - the PessimisticLockException will be thrown if the database
*
locking failure causes transaction-level rollback
* - the LockTimeoutException will be thrown if the database
*
locking failure causes only statement-level rollback
* If a vendor-specific property or hint is not recognized,
* it is silently ignored.
* Portable applications should not rely on the standard timeout
* hint. Depending on the database in use and the locking
* mechanisms used by the provider, the hint may or may not
* be observed.
* @param entityClass
* @param primaryKey
* @param lockMode
* @param properties standard and vendor-specific properties
*
and hints
* @return the found entity instance or null if the entity does
*
not exist
* @throws IllegalArgumentException if the first argument does
*
not denote an entity type or the second argument is
*
not a valid type for that entity's primary key or
*
is null
JSR-338 Final Release
67
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
* @throws
*
*
*
*
* @throws
*
* @throws
*
* @throws
*
* @throws
*
*/
public <T>
EntityManager
TransactionRequiredException if there is no
transaction and a lock mode other than NONE is
specified or if invoked on an entity manager which has
not been joined to the current transaction and a lock
mode other than NONE is specified
OptimisticLockException if the optimistic version
check fails
PessimisticLockException if pessimistic locking
fails and the transaction is rolled back
LockTimeoutException if pessimistic locking fails and
only the statement is rolled back
PersistenceException if an unsupported lock call
is made
T find(Class<T> entityClass,
Object primaryKey,
LockModeType lockMode,
Map<String, Object> properties);
/**
* Get an instance, whose state may be lazily fetched.
* If the requested instance does not exist in the database,
* the EntityNotFoundException is thrown when the instance
* state is first accessed. (The persistence provider runtime is
* permitted to throw the EntityNotFoundException when
* getReference is called.)
* The application should not expect that the instance state will
* be available upon detachment, unless it was accessed by the
* application while the entity manager was open.
* @param entityClass
* @param primaryKey
* @return the found entity instance
* @throws IllegalArgumentException if the first argument does
*
not denote an entity type or the second argument is
*
not a valid type for that entity’s primary key or
*
is null
* @throws EntityNotFoundException if the entity state
*
cannot be accessed
*/
public <T> T getReference(Class<T> entityClass,
Object primaryKey);
/**
* Synchronize the persistence context to the
* underlying database.
* @throws TransactionRequiredException if there is
*
no transaction or if the entity manager has not been
*
joined to the current transaction
* @throws PersistenceException if the flush fails
*/
public void flush();
/**
* Set the flush mode that applies to all objects contained
* in the persistence context.
* @param flushMode
*/
public void setFlushMode(FlushModeType flushMode);
4/2/13
68
JSR-338 Final Release
Oracle
EntityManager
Java Persistence 2.1, Final Release
Entity Operations
/**
* Get the flush mode that applies to all objects contained
* in the persistence context.
* @return flushMode
*/
public FlushModeType getFlushMode();
/**
* Lock an entity instance that is contained in the persistence
* context with the specified lock mode type.
* If a pessimistic lock mode type is specified and the entity
* contains a version attribute, the persistence provider must
* also perform optimistic version checks when obtaining the
* database lock. If these checks fail, the
* OptimisticLockException will be thrown.
* If the lock mode type is pessimistic and the entity instance
* is found but cannot be locked:
* - the PessimisticLockException will be thrown if the database
*
locking failure causes transaction-level rollback
* - the LockTimeoutException will be thrown if the database
*
locking failure causes only statement-level rollback
* @param entity
* @param lockMode
* @throws IllegalArgumentException if the instance is not an
*
entity or is a detached entity
* @throws TransactionRequiredException if there is no
*
transaction or if invoked on an entity manager which
*
has not been joined to the current transaction
* @throws EntityNotFoundException if the entity does not exist
*
in the database when pessimistic locking is
*
performed
* @throws OptimisticLockException if the optimistic version
*
check fails
* @throws PessimisticLockException if pessimistic locking fails
*
and the transaction is rolled back
* @throws LockTimeoutException if pessimistic locking fails and
*
only the statement is rolled back
* @throws PersistenceException if an unsupported lock call
*
is made
*/
public void lock(Object entity, LockModeType lockMode);
/**
* Lock an entity instance that is contained in the persistence
* context with the specified lock mode type and with specified
* properties.
* If a pessimistic lock mode type is specified and the entity
* contains a version attribute, the persistence provider must
* also perform optimistic version checks when obtaining the
* database lock. If these checks fail, the
* OptimisticLockException will be thrown.
* If the lock mode type is pessimistic and the entity instance
* is found but cannot be locked:
* - the PessimisticLockException will be thrown if the database
*
locking failure causes transaction-level rollback
* - the LockTimeoutException will be thrown if the database
*
locking failure causes only statement-level rollback
* If a vendor-specific property or hint is not recognized,
JSR-338 Final Release
69
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
EntityManager
* it is silently ignored.
* Portable applications should not rely on the standard timeout
* hint. Depending on the database in use and the locking
* mechanisms used by the provider, the hint may or may not
* be observed.
* @param entity
* @param lockMode
* @param properties standard and vendor-specific properties
*
and hints
* @throws IllegalArgumentException if the instance is not an
*
entity or is a detached entity
* @throws TransactionRequiredException if there is no
*
transaction or if invoked on an entity manager which
*
has not been joined to the current transaction
* @throws EntityNotFoundException if the entity does not exist
*
in the database when pessimistic locking is
*
performed
* @throws OptimisticLockException if the optimistic version
*
check fails
* @throws PessimisticLockException if pessimistic locking fails
*
and the transaction is rolled back
* @throws LockTimeoutException if pessimistic locking fails and
*
only the statement is rolled back
* @throws PersistenceException if an unsupported lock call
*
is made
*/
public void lock(Object entity,
LockModeType lockMode,
Map<String, Object> properties);
/**
* Refresh the state of the instance from the database,
* overwriting changes made to the entity, if any.
* @param entity
* @throws IllegalArgumentException if the instance is not
*
an entity or the entity is not managed
* @throws TransactionRequiredException if there is no
*
transaction when invoked on a container-managed
*
entity manager that is of type
*
PersistenceContextType.TRANSACTION.
* @throws EntityNotFoundException if the entity no longer
*
exists in the database
*/
public void refresh(Object entity);
/**
* Refresh the state of the instance from the database, using
* the specified properties, and overwriting changes made to
* the entity, if any.
* If a vendor-specific property or hint is not recognized,
* it is silently ignored.
* @param entity
* @param properties standard and vendor-specific properties
*
and hints
* @throws IllegalArgumentException if the instance is not
*
an entity or the entity is not managed
* @throws TransactionRequiredException if there is no
*
transaction when invoked on a container-managed
*
entity manager that is of type
4/2/13
70
JSR-338 Final Release
Oracle
EntityManager
Java Persistence 2.1, Final Release
Entity Operations
*
PersistenceContextType.TRANSACTION.
* @throws EntityNotFoundException if the entity no longer
*
exists in the database
*/
public void refresh(Object entity,
Map<String, Object> properties);
/**
* Refresh the state of the instance from the database,
* overwriting changes made to the entity, if any, and
* lock it with respect to given lock mode type.
* If the lock mode type is pessimistic and the entity instance
* is found but cannot be locked:
* - the PessimisticLockException will be thrown if the database
*
locking failure causes transaction-level rollback
* - the LockTimeoutException will be thrown if the
*
database locking failure causes only statement-level
*
rollback.
* @param entity
* @param lockMode
* @throws IllegalArgumentException if the instance is not
*
an entity or the entity is not managed
* @throws TransactionRequiredException if invoked on an entity
*
manager of type PersistenceContextType.TRANSACTION
*
when there is no transaction; if invoked on an
*
extended entity manager when there is no transaction
*
and a lock mode other than NONE has been specified;
*
or if invoked on an extended entity manager that has
*
not been joined to the current transaction and a lock
*
mode other than NONE has been specified
* @throws EntityNotFoundException if the entity no longer exists
*
in the database
* @throws PessimisticLockException if pessimistic locking fails
*
and the transaction is rolled back
* @throws LockTimeoutException if pessimistic locking fails and
*
only the statement is rolled back
* @throws PersistenceException if an unsupported lock call
*
is made
*/
public void refresh(Object entity, LockModeType lockMode);
/**
* Refresh the state of the instance from the database,
* overwriting changes made to the entity, if any, and
* lock it with respect to given lock mode type and with
* specified properties.
* If the lock mode type is pessimistic and the entity instance
* is found but cannot be locked:
* - the PessimisticLockException will be thrown if the database
*
locking failure causes transaction-level rollback
* - the LockTimeoutException will be thrown if the database
*
locking failure causes only statement-level rollback
* If a vendor-specific property or hint is not recognized,
* it is silently ignored.
* Portable applications should not rely on the standard timeout
* hint. Depending on the database in use and the locking
* mechanisms used by the provider, the hint may or may not
* be observed.
* @param entity
JSR-338 Final Release
71
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
EntityManager
* @param lockMode
* @param properties standard and vendor-specific properties
*
and hints
* @throws IllegalArgumentException if the instance is not
*
an entity or the entity is not managed
* @throws TransactionRequiredException if invoked on an entity
*
manager of type PersistenceContextType.TRANSACTION
*
when there is no transaction; if invoked on an
*
extended entity manager when there is no transaction
*
and a lock mode other than NONE has been specified;
*
or if invoked on an extended entity manager that has
*
not been joined to the current transaction and a lock
*
mode other than NONE has been specified
* @throws EntityNotFoundException if the entity no longer exists
*
in the database
* @throws PessimisticLockException if pessimistic locking fails
*
and the transaction is rolled back
* @throws LockTimeoutException if pessimistic locking fails and
*
only the statement is rolled back
* @throws PersistenceException if an unsupported lock call
*
is made
*/
public void refresh(Object entity,
LockModeType lockMode,
Map<String, Object> properties);
/**
* Clear the persistence context, causing all managed
* entities to become detached. Changes made to entities that
* have not been flushed to the database will not be
* persisted.
*/
public void clear();
/**
* Remove the given entity from the persistence context, causing
* a managed entity to become detached. Unflushed changes made
* to the entity if any (including removal of the entity),
* will not be synchronized to the database. Entities which
* previously referenced the detached entity will continue to
* reference it.
* @param entity
* @throws IllegalArgumentException if the instance is not an
*
entity
*/
public void detach(Object entity);
/**
* Check if the instance is a managed entity instance belonging
* to the current persistence context.
* @param entity
* @return boolean indicating if entity is in persistence context
* @throws IllegalArgumentException if not an entity
*/
public boolean contains(Object entity);
4/2/13
72
JSR-338 Final Release
Oracle
EntityManager
Java Persistence 2.1, Final Release
Entity Operations
/**
* Get the current lock mode for the entity instance.
* @param entity
* @return lock mode
* @throws TransactionRequiredException if there is no
*
transaction or if the entity manager has not been
*
joined to the current transaction
* @throws IllegalArgumentException if the instance is not a
*
managed entity and a transaction is active
*/
public LockModeType getLockMode(Object entity);
/**
* Set an entity manager property or hint. If a vendor-specific
* property or hint is not recognized, it is silently ignored.
* @param propertyName name of property or hint
* @param value
* @throws IllegalArgumentException if the second argument is
*
not valid for the implementation
*/
public void setProperty(String propertyName, Object value);
/**
* Get the properties and hints and associated values that are
* in effect for the entity manager. Changing the contents of
* the map does not change the configuration in effect.
* @return map of properties and hints in effect
*/
public Map<String, Object> getProperties();
/**
* Create an instance of Query for executing a
* Java Persistence query language statement.
* @param qlString a Java Persistence query string
* @return the new query instance
* @throws IllegalArgumentException if the query string is
*
found to be invalid
*/
public Query createQuery(String qlString);
/**
* Create an instance of TypedQuery for executing a
* criteria query.
* @param criteriaQuery a criteria query object
* @return the new query instance
* @throws IllegalArgumentException if the criteria query is
*
found to be invalid
*/
public <T> TypedQuery<T> createQuery(
CriteriaQuery<T> criteriaQuery);
/**
* Create an instance of Query for executing a criteria
* update query.
* @param updateQuery a criteria update query object
* @return the new query instance
* @throws IllegalArgumentException if the update query is
*
found to be invalid
*/
public Query createQuery(CriteriaUpdate updateQuery);
JSR-338 Final Release
73
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
EntityManager
/**
* Create an instance of Query for executing a criteria
* delete query.
* @param deleteQuery a criteria delete query object
* @return the new query instance
* @throws IllegalArgumentException if the delete query is
*
found to be invalid
*/
public Query createQuery(CriteriaDelete deleteQuery);
/**
* Create an instance of TypedQuery for executing a
* Java Persistence query language statement.
* The select list of the query must contain only a single
* item, which must be assignable to the type specified by
* the resultClass argument.[26]
* @param qlString a Java Persistence query string
* @param resultClass the type of the query result
* @return the new query instance
* @throws IllegalArgumentException if the query string is found
*
to be invalid or if the query result is found to
*
not be assignable to the specified type
*/
public <T> TypedQuery<T> createQuery(String qlString,
Class<T> resultClass);
/**
* Create an instance of Query for executing a named query
* (in the Java Persistence query language or in native SQL).
* @param name the name of a query defined in metadata
* @return the new query instance
* @throws IllegalArgumentException if a query has not been
*
defined with the given name or if the query string is
*
found to be invalid
*/
public Query createNamedQuery(String name);
/**
* Create an instance of TypedQuery for executing a
* Java Persistence query language named query.
* The select list of the query must contain only a single
* item, which must be assignable to the type specified by
* the resultClass argument.[27]
* @param name the name of a query defined in metadata
* @param resultClass the type of the query result
* @return the new query instance
* @throws IllegalArgumentException if a query has not been
*
defined with the given name or if the query string is
*
found to be invalid or if the query result is found to
*
not be assignable to the specified type
*/
public <T> TypedQuery<T> createNamedQuery(String name,
Class<T> resultClass);
[26] The semantics of this method may be extended in a future release of this specification to support other result types. Applications
that specify other result types (e.g., Tuple.class) will not be portable.
[27] The semantics of this method may be extended in a future release of this specification to support other result types. Applications
that specify other result types (e.g., Tuple.class) will not be portable.
4/2/13
74
JSR-338 Final Release
Oracle
EntityManager
Java Persistence 2.1, Final Release
Entity Operations
/**
* Create an instance of Query for executing a native SQL
* statement, e.g., for update or delete.
* If the query is not an update or delete query, query
* execution will result in each row of the SQL result
* being returned as a result of type Object[] (or a result
* of type Object if there is only one column in the select
* list.) Column values are returned in the order of their
* appearance in the select list and default JDBC type
* mappings are applied.
* @param sqlString a native SQL query string
* @return the new query instance
*/
public Query createNativeQuery(String sqlString);
/**
* Create an instance of Query for executing
* a native SQL query.
* @param sqlString a native SQL query string
* @param resultClass the class of the resulting instance(s)
* @return the new query instance
*/
public Query createNativeQuery(String sqlString,
Class resultClass);
/**
* Create an instance of Query for executing
* a native SQL query.
* @param sqlString a native SQL query string
* @param resultSetMapping the name of the result set mapping
* @return the new query instance
*/
public Query createNativeQuery(String sqlString,
String resultSetMapping);
/**
* Create an instance of StoredProcedureQuery for executing a
* stored procedure in the database.
* @param name name assigned to the stored procedure query
*
in metadata
* @return the new stored procedure query instance
* @throws IllegalArgumentException if a query has not been
*
defined with the given name
*/
public StoredProcedureQuery createNamedStoredProcedureQuery(
String name);
/**
* Create an instance of StoredProcedureQuery for executing a
* stored procedure in the database.
* Parameters must be registered before the stored procedure can
* be executed.
* If the stored procedure returns one or more result sets,
* any result set will be returned as a list of type Object[].
* @param procedureName name of the stored procedure in the
*
database
* @return the new stored procedure query instance
* @throws IllegalArgumentException if a stored procedure of the
*
given name does not exist (or the query execution
JSR-338 Final Release
75
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
EntityManager
*
will fail)
*/
public StoredProcedureQuery createStoredProcedureQuery(
String procedureName);
/**
* Create an instance of StoredProcedureQuery for executing a
* stored procedure in the database.
* Parameters must be registered before the stored procedure can
* be executed.
* The resultClass arguments must be specified in the order in
* which the result sets will be returned by the stored procedure
* invocation.
* @param procedureName name of the stored procedure in the
*
database
* @param resultClasses classes to which the result sets
*
produced by the stored procedure are to
*
be mapped
* @return the new stored procedure query instance
* @throws IllegalArgumentException if a stored procedure of the
*
given name does not exist (or the query execution
*
will fail)
*/
public StoredProcedureQuery createStoredProcedureQuery(
String procedureName, Class... resultClasses);
/**
* Create an instance of StoredProcedureQuery for executing a
* stored procedure in the database.
* Parameters must be registered before the stored procedure can
* be executed.
* The resultSetMapping arguments must be specified in the order
* in which the result sets will be returned by the stored
* procedure invocation.
* @param procedureName name of the stored procedure in the
*
database
* @param resultSetMappings the names of the result set mappings
*
to be used in mapping result sets
*
returned by the stored procedure
* @return the new stored procedure query instance
* @throws IllegalArgumentException if a stored procedure or
*
result set mapping of the given name does not exist
*
(or the query execution will fail)
*/
public StoredProcedureQuery createStoredProcedureQuery(
String procedureName, String... resultSetMappings);
/**
* Indicate to the entity manager that a JTA transaction is
* active. This method should be called on a JTA application
* managed entity manager that was created outside the scope
* of the active transaction or on an entity manager of type
* SynchronizationType.UNSYNCHRONIZED to associate it with the
* current JTA transaction.
* @throws TransactionRequiredException if there is
*
no transaction
*/
public void joinTransaction();
4/2/13
76
JSR-338 Final Release
Oracle
EntityManager
Java Persistence 2.1, Final Release
Entity Operations
/**
* Determine whether the entity manager is joined to the
* current transaction. Returns false if the entity manager
* is not joined to the current transaction or if no
* transaction is active
* @return boolean
*/
public boolean isJoinedToTransaction();
/**
* Return an object of the specified type to allow access to the
* provider-specific API.
If the provider's EntityManager
* implementation does not support the specified class, the
* PersistenceException is thrown.
* @param cls the class of the object to be returned. This is
* normally either the underlying EntityManager implementation
* class or an interface that it implements.
* @return an instance of the specified class
* @throws PersistenceException if the provider does not
*
support the call
*/
public <T> T unwrap(Class<T> cls);
/**
* Return the underlying provider object for the EntityManager,
* if available. The result of this method is implementation
* specific. The unwrap method is to be preferred for new
* applications.
* @return underlying provider object for EntityManager
*/
public Object getDelegate();
/**
* Close an application-managed entity manager.
* After the close method has been invoked, all methods
* on the EntityManager instance and any Query, TypedQuery, and
* StoredProcedureQuery objects obtained from it will throw the
* IllegalStateException except for getProperties,
* getTransaction, and isOpen (which will return false).
* If this method is called when the entity manager is
* joined to an active transaction, the persistence
* context remains managed until the transaction completes.
* @throws IllegalStateException if the entity manager
*
is container-managed
*/
public void close();
/**
* Determine whether the entity manager is open.
* @return true until the entity manager has been closed
*/
public boolean isOpen();
JSR-338 Final Release
77
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
EntityManager
/**
* Return the resource-level EntityTransaction object.
* The EntityTransaction instance may be used serially to
* begin and commit multiple transactions.
* @return EntityTransaction instance
* @throws IllegalStateException if invoked on a JTA
*
entity manager
*/
public EntityTransaction getTransaction();
/**
* Return the entity manager factory for the entity manager.
* @return EntityManagerFactory instance
* @throws IllegalStateException if the entity manager has
*
been closed
*/
public EntityManagerFactory getEntityManagerFactory();
/**
* Return an instance of CriteriaBuilder for the creation of
* CriteriaQuery objects.
* @return CriteriaBuilder instance
* @throws IllegalStateException if the entity manager has
*
been closed
*/
public CriteriaBuilder getCriteriaBuilder();
/**
* Return an instance of Metamodel interface for access to the
* metamodel of the persistence unit.
* @return Metamodel instance
* @throws IllegalStateException if the entity manager has
*
been closed
*/
public Metamodel getMetamodel();
/**
* Return a mutable EntityGraph that can be used to dynamically
* create an EntityGraph.
* @param rootType class of entity graph
* @return entity graph
*/
public <T> EntityGraph<T> createEntityGraph(Class<T> rootType);
/**
* Return a mutable copy of the named EntityGraph. If there
* is no entity graph with the specified name, null is returned.
* @param graphName name of an entity graph
* @return entity graph
*/
public EntityGraph<?> createEntityGraph(String graphName);
4/2/13
78
JSR-338 Final Release
Oracle
EntityManager
Java Persistence 2.1, Final Release
Entity Operations
/**
* Return a named EntityGraph. The returned EntityGraph
* should be considered immutable.
* @param graphName name of an existing entity graph
* @return named entity graph
* @throws IllegalArgumentException if there is no EntityGraph of
*
the given name
*/
public EntityGraph<?> getEntityGraph(String graphName);
}
/**
* Return all named EntityGraphs that have been defined for the
* provided class type.
* @param entityClass entity class
* @return list of all entity graphs defined for the entity
* @throws IllegalArgumentException if the class is not an entity
*/
public <T> List<EntityGraph<? super T>>
getEntityGraphs(Class<T> entityClass);
The persist, merge, remove, and refresh methods must be invoked within a transaction context when an entity manager with a transaction-scoped persistence context is used. If there is no transaction context, the javax.persistence.TransactionRequiredException is thrown.
Methods that specify a lock mode other than LockModeType.NONE must be invoked within a transaction. If there is no transaction or if the entity manager has not been joined to the transaction, the
javax.persistence.TransactionRequiredException is thrown.
The find method (provided it is invoked without a lock or invoked with LockModeType.NONE)
and the getReference method are not required to be invoked within a transaction. If an entity manager with transaction-scoped persistence context is in use, the resulting entities will be detached; if an
entity manager with an extended persistence context is used, they will be managed. See section 3.3 for
entity manager use outside a transaction.
The Query, TypedQuery, StoredProcedureQuery, CriteriaBuilder, Metamodel, and
EntityTransaction objects obtained from an entity manager are valid while that entity manager is
open.
If the argument to the createQuery method is not a valid Java Persistence query string or a valid
CriteriaQuery object, the IllegalArgumentException may be thrown or the query execution will fail and a PersistenceException will be thrown. If the result class specification of a
Java Persistence query language query is incompatible with the result of the query, the IllegalArgumentException may be thrown when the createQuery method is invoked or the query execution will fail and a PersistenceException will be thrown when the query is executed. If a native
query is not a valid query for the database in use or if the result set specification is incompatible with the
result of the query, the query execution will fail and a PersistenceException will be thrown
when the query is executed. The PersistenceException should wrap the underlying database
exception when possible.
Runtime exceptions thrown by the methods of the EntityManager interface other than the LockTimeoutException will cause the current transaction to be marked for rollback if the persistence
context is joined to that transaction.
JSR-338 Final Release
79
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Entity Instance’s Life Cycle
The methods close, isOpen, joinTransaction, and getTransaction are used to manage
application-managed entity managers and their lifecycle. See Section 7.2.2, “Obtaining an Application-managed Entity Manager”.
The EntityManager interface and other interfaces defined by this specification contain methods that
take properties and/or hints as arguments. This specification distinguishes between properties and hints
as follows:
• A property defined by this specification must be observed by the provider unless otherwise
explicitly stated.
• A hint specifies a preference on the part of the application. While a hint defined by this specification should be observed by the provider if possible, a hint may or may not always be
observed. A portable application must not depend on the observance of a hint.
3.1.2 Example of Use of EntityManager API
@Stateless public class OrderEntryBean implements OrderEntry {
@PersistenceContext EntityManager em;
}
public void enterOrder(int custID, Order newOrder) {
Customer cust = em.find(Customer.class, custID);
cust.getOrders().add(newOrder);
newOrder.setCustomer(cust);
em.persist(newOrder);
}
3.2 Entity Instance’s Life Cycle
This section describes the EntityManager operations for managing an entity instance’s lifecycle. An
entity instance can be characterized as being new, managed, detached, or removed.
• A new entity instance has no persistent identity, and is not yet associated with a persistence
context.
• A managed entity instance is an instance with a persistent identity that is currently associated
with a persistence context.
• A detached entity instance is an instance with a persistent identity that is not (or no longer)
associated with a persistence context.
• A removed entity instance is an instance with a persistent identity, associated with a persistence context, that will be removed from the database upon transaction commit.
4/2/13
80
JSR-338 Final Release
Oracle
Entity Instance’s Life Cycle
Java Persistence 2.1, Final Release
Entity Operations
The following subsections describe the effect of lifecycle operations upon entities. Use of the cascade
annotation element may be used to propagate the effect of an operation to associated entities. The cascade functionality is most typically used in parent-child relationships.
3.2.1 Entity Instance Creation
Entity instances are created by means of the new operation. An entity instance, when first created by
new is not yet persistent. An instance becomes persistent by means of the EntityManager API.
3.2.2 Persisting an Entity Instance
A new entity instance becomes both managed and persistent by invoking the persist method on it or
by cascading the persist operation.
The semantics of the persist operation, applied to an entity X are as follows:
• If X is a new entity, it becomes managed. The entity X will be entered into the database at or
before transaction commit or as a result of the flush operation.
• If X is a preexisting managed entity, it is ignored by the persist operation. However, the persist
operation is cascaded to entities referenced by X, if the relationships from X to these other
entities are annotated with the cascade=PERSIST or cascade=ALL annotation element
value or specified with the equivalent XML descriptor element.
• If X is a removed entity, it becomes managed.
• If X is a detached object, the EntityExistsException may be thrown when the persist
operation is invoked, or the EntityExistsException or another PersistenceException may be thrown at flush or commit time.
• For all entities Y referenced by a relationship from X, if the relationship to Y has been annotated with the cascade element value cascade=PERSIST or cascade=ALL, the persist
operation is applied to Y.
3.2.3 Removal
A managed entity instance becomes removed by invoking the remove method on it or by cascading the
remove operation.
The semantics of the remove operation, applied to an entity X are as follows:
• If X is a new entity, it is ignored by the remove operation. However, the remove operation is
cascaded to entities referenced by X, if the relationship from X to these other entities is annotated with the cascade=REMOVE or cascade=ALL annotation element value.
JSR-338 Final Release
81
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Entity Instance’s Life Cycle
• If X is a managed entity, the remove operation causes it to become removed. The remove oper-
ation is cascaded to entities referenced by X, if the relationships from X to these other entities
is annotated with the cascade=REMOVE or cascade=ALL annotation element value.
• If X is a detached entity, an IllegalArgumentException will be thrown by the remove
operation (or the transaction commit will fail).
• If X is a removed entity, it is ignored by the remove operation.
• A removed entity X will be removed from the database at or before transaction commit or as a
result of the flush operation.
After an entity has been removed, its state (except for generated state) will be that of the entity at the
point at which the remove operation was called.
3.2.4 Synchronization to the Database
In general, a persistence context will be synchronized to the database as described below. However, a
persistence context of type SynchronizationType.UNSYNCHRONIZED or an application-managed persistence context that has been created outside the scope of the current transaction will only be
synchronized to the database if it has been joined to the current transaction by the application’s use of
the EntityManager joinTransaction method.
The state of persistent entities is synchronized to the database at transaction commit. This synchronization involves writing to the database any updates to persistent entities and their relationships as specified above.
An update to the state of an entity includes both the assignment of a new value to a persistent property
or field of the entity as well as the modification of a mutable value of a persistent property or field[28].
Synchronization to the database does not involve a refresh of any managed entities unless the refresh
operation is explicitly invoked on those entities or cascaded to them as a result of the specification of
the cascade=REFRESH or cascade=ALL annotation element value.
Bidirectional relationships between managed entities will be persisted based on references held by the
owning side of the relationship. It is the developer’s responsibility to keep the in-memory references
held on the owning side and those held on the inverse side consistent with each other when they change.
In the case of unidirectional one-to-one and one-to-many relationships, it is the developer’s responsibility to insure that the semantics of the relationships are adhered to.[29]
It is particularly important to ensure that changes to the inverse side of a relationship result in
appropriate updates on the owning side, so as to ensure the changes are not lost when they are
synchronized to the database.
[28] This includes, for example. modifications to persistent attributes of type char[] and byte[].
[29] This might be an issue if unique constraints (such as those described for the default mappings in sections 2.10.3.1 and 2.10.5.1)
were not applied in the definition of the object/relational mapping.
4/2/13
82
JSR-338 Final Release
Oracle
Entity Instance’s Life Cycle
Java Persistence 2.1, Final Release
Entity Operations
The persistence provider runtime is permitted to perform synchronization to the database at other times
as well when a transaction is active and the persistence context is joined to the transaction. The flush
method can be used by the application to force synchronization. It applies to entities associated with the
persistence context. The setFlushMode methods of the EntityManager, Query,
TypedQuery, and StoredProcedureQuery interfaces can be used to control synchronization
semantics. The effect of FlushModeType.AUTO is defined in section 3.10.8. If FlushModeType.COMMIT is specified, flushing will occur at transaction commit; the persistence provider is permitted, but not required, to perform to flush at other times. If there is no transaction active or if the
persistence context has not been joined to the current transaction, the persistence provider must not
flush to the database.
The semantics of the flush operation, applied to an entity X are as follows:
• If X is a managed entity, it is synchronized to the database.
• For all entities Y referenced by a relationship from X, if the relationship to Y has been
annotated with the cascade element value cascade=PERSIST or cascade=ALL, the persist operation is applied to Y.
• For any entity Y referenced by a relationship from X, where the relationship to Y has
not been annotated with the cascade element value cascade=PERSIST or cascade=ALL:
• If Y is new or removed, an IllegalStateException will be thrown
by the flush operation (and the transaction marked for rollback) or the transaction commit will fail.
• If Y is detached, the semantics depend upon the ownership of the relation-
ship. If X owns the relationship, any changes to the relationship are synchronized with the database; otherwise, if Y owns the relationships, the behavior
is undefined.
• If X is a removed entity, it is removed from the database. No cascade options are relevant.
3.2.5 Refreshing an Entity Instance
The state of a managed entity instance is refreshed from the database by invoking the refresh method
on it or by cascading the refresh operation.
The semantics of the refresh operation, applied to an entity X are as follows:
• If X is a managed entity, the state of X is refreshed from the database, overwriting changes
made to the entity, if any. The refresh operation is cascaded to entities referenced by X if the
relationship from X to these other entities is annotated with the cascade=REFRESH or
cascade=ALL annotation element value.
• If X is a new, detached, or removed entity, the IllegalArgumentException is thrown.
JSR-338 Final Release
83
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Entity Instance’s Life Cycle
3.2.6 Evicting an Entity Instance from the Persistence Context
An entity instance is removed from the persistence context by invoking the detach method on it or
cascading the detach operation. Changes made to the entity, if any (including removal of the entity),
will not be synchronized to the database after such eviction has taken place.
Applications must use the flush method prior to the detach method to ensure portable semantics if
changes have been made to the entity (including removal of the entity). Because the persistence provider may write to the database at times other than the explicit invocation of the flush method, portable applications must not assume that changes have not been written to the database if the flush
method has not been called prior to detach.
The semantics of the detach operation, applied to an entity X are as follows:
• If X is a managed entity, the detach operation causes it to become detached. The detach opera-
tion is cascaded to entities referenced by X if the relationships from X to these other entities is
annotated with the cascade=DETACH or cascade=ALL annotation element value. Entities
which previously referenced X will continue to reference X.
• If X is a new or detached entity, it is ignored by the detach operation.
• If X is a removed entity, the detach operation causes it to become detached. The detach opera-
tion is cascaded to entities referenced by X if the relationships from X to these other entities is
annotated with the cascade=DETACH or cascade=ALL annotation element value. Entities
which previously referenced X will continue to reference X. Portable applications should not
pass removed entities that have been detached from the persistence context to further EntityManager operations.
3.2.7 Detached Entities
A detached entity results from transaction commit if a transaction-scoped persistence context is used
(see section 3.3); from transaction rollback (see section 3.3.3); from detaching the entity from the persistence context; from clearing the persistence context; from closing an entity manager; or from serializing an entity or otherwise passing an entity by value—e.g., to a separate application tier, through a
remote interface, etc.
Detached entity instances continue to live outside of the persistence context in which they were persisted or retrieved. Their state is no longer guaranteed to be synchronized with the database state.
The application may access the available state of available detached entity instances after the persistence context ends. The available state includes:
• Any persistent field or property not marked fetch=LAZY
• Any persistent field or property that was accessed by the application or fetched by means of an
entity graph
4/2/13
84
JSR-338 Final Release
Oracle
Entity Instance’s Life Cycle
Java Persistence 2.1, Final Release
Entity Operations
If the persistent field or property is an association, the available state of an associated instance may only
be safely accessed if the associated instance is available. The available instances include:
• Any entity instance retrieved using find().
• Any entity instances retrieved using a query or explicitly requested in a fetch join.
• Any entity instance for which an instance variable holding non-primary-key persistent state
was accessed by the application.
• Any entity instance that can be reached from another available instance by navigating associations marked fetch=EAGER.
3.2.7.1 Merging Detached Entity State
The merge operation allows for the propagation of state from detached entities onto persistent entities
managed by the entity manager.
The semantics of the merge operation applied to an entity X are as follows:
• If X is a detached entity, the state of X is copied onto a pre-existing managed entity instance X'
of the same identity or a new managed copy X' of X is created.
• If X is a new entity instance, a new managed entity instance X' is created and the state of X is
copied into the new managed entity instance X'.
• If X is a removed entity instance, an IllegalArgumentException will be thrown by the
merge operation (or the transaction commit will fail).
• If X is a managed entity, it is ignored by the merge operation, however, the merge operation is
cascaded to entities referenced by relationships from X if these relationships have been annotated with the cascade element value cascade=MERGE or cascade=ALL annotation.
• For all entities Y referenced by relationships from X having the cascade element value
cascade=MERGE or cascade=ALL, Y is merged recursively as Y'. For all such Y referenced by X, X' is set to reference Y'. (Note that if X is managed then X is the same object as
X'.)
• If X is an entity merged to X', with a reference to another entity Y, where cascade=MERGE
or cascade=ALL is not specified, then navigation of the same association from X' yields a
reference to a managed object Y' with the same persistent identity as Y.
The persistence provider must not merge fields marked LAZY that have not been fetched: it must ignore
such fields when merging.
Any Version columns used by the entity must be checked by the persistence runtime implementation
during the merge operation and/or at flush or commit time. In the absence of Version columns there is
no additional version checking done by the persistence provider runtime during the merge operation.
JSR-338 Final Release
85
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Entity Instance’s Life Cycle
3.2.7.2 Detached Entities and Lazy Loading
Serializing entities and merging those entities back into a persistence context may not be interoperable
across vendors when lazy properties or fields and/or relationships are used.
A vendor is required to support the serialization and subsequent deserialization and merging of detached
entity instances (which may contain lazy properties or fields and/or relationships that have not been
fetched) back into a separate JVM instance of that vendor's runtime, where both runtime instances have
access to the entity classes and any required vendor persistence implementation classes.
When interoperability across vendors is required, the application must not use lazy loading.
3.2.8 Managed Instances
It is the responsibility of the application to insure that an instance is managed in only a single persistence context. The behavior is undefined if the same Java instance is made managed in more than one
persistence context.
The contains() method can be used to determine whether an entity instance is managed in the current persistence context.
The contains method returns true:
• If the entity has been retrieved from the database or has been returned by getReference,
and has not been removed or detached.
• If the entity instance is new, and the persist method has been called on the entity or the persist operation has been cascaded to it.
The contains method returns false:
• If the instance is detached.
• If the remove method has been called on the entity, or the remove operation has been cascaded to it.
• If the instance is new, and the persist method has not been called on the entity or the persist
operation has not been cascaded to it.
Note that the effect of the cascading of persist, merge, remove, or detach is immediately visible to the
contains method, whereas the actual insertion, modification, or deletion of the database representation for the entity may be deferred until the end of the transaction.
3.2.9 Load State
An entity is considered to be loaded if all attributes with FetchType.EAGER—whether explictly
specified or by default—(including relationship and other collection-valued attributes) have been
loaded from the database or assigned by the application. Attributes with FetchType.LAZY may or
may not have been loaded. The available state of the entity instance and associated instances is as
described in section 3.2.7.
4/2/13
86
JSR-338 Final Release
Oracle
Persistence Context Lifetime and Synchronization TypeJava Persistence 2.1, Final Release
Entity Operations
An attribute that is an embeddable is considered to be loaded if the embeddable attribute was loaded
from the database or assigned by the application, and, if the attribute references an embeddable instance
(i.e., is not null), the embeddable instance state is known to be loaded (i.e., all attributes of the
embeddable with FetchType.EAGER have been loaded from the database or assigned by the application).
A collection-valued attribute is considered to be loaded if the collection was loaded from the database
or the value of the attribute was assigned by the application, and, if the attribute references a collection
instance (i.e., is not null), each element of the collection (e.g. entity or embeddable) is considered to be
loaded.
A single-valued relationship attribute is considered to be loaded if the relationship attribute was loaded
from the database or assigned by the application, and, if the attribute references an entity instance (i.e.,
is not null), the entity instance state is known to be loaded.
A basic attribute is considered to be loaded if its state has been loaded from the database or assigned by
the application.
The PersistenceUtil.isLoaded methods can be used to determine the load state of an entity
and its attributes regardless of the persistence unit with which the entity is associated. The PersistenceUtil.isLoaded methods return true if the above conditions hold, and false otherwise. If the
persistence unit is known, the PersistenceUnitUtil.isLoaded methods can be used instead.
See section 7.11.
Persistence provider contracts for determining the load state of an entity or entity attribute are described
in section 9.8.1.
3.3 Persistence Context Lifetime and Synchronization Type
The lifetime of a container-managed persistence context can either be scoped to a transaction (transaction-scoped persistence context), or have a lifetime scope that extends beyond that of a single transaction (extended persistence context). The enum PersistenceContextType is used to define the
persistence context lifetime scope for container-managed entity managers. The persistence context lifetime scope is defined when the EntityManager instance is created (whether explicitly, or in conjunction
with injection or JNDI lookup). See Section 7.6.
package javax.persistence;
public enum PersistenceContextType {
TRANSACTION,
EXTENDED
}
By default, the lifetime of the persistence context of a container-managed entity manager corresponds to
the scope of a transaction (i.e., it is of type PersistenceContextType.TRANSACTION).
When an extended persistence context is used, the extended persistence context exists from the time the
EntityManager instance is created until it is closed. This persistence context might span multiple transactions and non-transactional invocations of the EntityManager.
JSR-338 Final Release
87
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final ReleasePersistence Context Lifetime and Synchronization
An EntityManager with an extended persistence context maintains its references to the entity objects
after a transaction has committed. Those objects remain managed by the EntityManager, and they can
be updated as managed objects between transactions.[30] Navigation from a managed object in an
extended persistence context results in one or more other managed objects regardless of whether a transaction is active.
When an EntityManager with an extended persistence context is used, the persist, remove, merge, and
refresh operations can be called regardless of whether a transaction is active. The effects of these operations will be committed to the database when the extended persistence context is enlisted in a transaction and the transaction commits.
The scope of the persistence context of an application-managed entity manager is extended. It is the
responsibility of the application to manage the lifecycle of the persistence context.
Container-managed persistence contexts are described further in section 7.6. Persistence contexts managed by the application are described further in section 7.7.
3.3.1 Synchronization with the Current Transaction
By default, a container-managed persistence context is of SynchronizationType.SYNCHRONIZED and is automatically joined to the current transaction. A persistence context of SynchronizationType.UNSYNCHRONIZED will not be enlisted in the current transaction, unless the
EntityManager joinTransaction method is invoked.
By default, an application-managed persistence context that is associated with a JTA entity manager and
that is created within the scope of an active transaction is automatically joined to that transaction. An
application-managed JTA persistence context that is created outside the scope of a transaction or an
application-managed persistence context of type SynchronizationType.UNSYNCHRONIZED
will not be joined to that transaction unless the EntityManager joinTransaction method is
invoked.
An application-managed persistence context associated with a resource-local entity manager is always
automatically joined to any resource-local transaction that is begun for that entity manager.
Persistence context synchronization type is described further in section 7.6.1.
3.3.2 Transaction Commit
The managed entities of a transaction-scoped persistence context become detached when the transaction
commits; the managed entities of an extended persistence context remain managed.
[30] Note that when a new transaction is begun, the managed objects in an extended persistence context are not reloaded from the database.
4/2/13
88
JSR-338 Final Release
Oracle
Locking and Concurrency
Java Persistence 2.1, Final Release
Entity Operations
3.3.3 Transaction Rollback
For both transaction-scoped persistence contexts and for extended persistence contexts that are joined to
the current transaction, transaction rollback causes all pre-existing managed instances and removed
instances[31] to become detached. The instances’ state will be the state of the instances at the point at
which the transaction was rolled back. Transaction rollback typically causes the persistence context to
be in an inconsistent state at the point of rollback. In particular, the state of version attributes and generated state (e.g., generated primary keys) may be inconsistent. Instances that were formerly managed by
the persistence context (including new instances that were made persistent in that transaction) may
therefore not be reusable in the same manner as other detached objects—for example, they may fail
when passed to the merge operation.[32]
NOTE: Because a transaction-scoped persistence context’s lifetime is scoped to a transaction
regardless of whether it is joined to that transaction, the container closes the persistence context upon transaction rollback. However, an extended persistence context that is not joined to a
transaction is unaffected by transaction rollback.
3.4 Locking and Concurrency
This specification assumes the use of optimistic concurrency control. It assumes that the databases to
which persistence units are mapped will be accessed by the implementation using read-committed isolation (or a vendor equivalent in which long-term read locks are not held), and that writes to the database
will typically occur only when the flush method has been invoked—whether explicitly by the application, or by the persistence provider runtime in accordance with the flush mode setting.
If a transaction is active and the persistence context is joined to the transaction, a compliant
implementation of this specification is permitted to write to the database immediately (i.e.,
whenever a managed entity is updated, created, and/or removed), however, the configuration
of an implementation to require such non-deferred database writes is outside the scope of this
specification. [33]
In addition, both pessimistic and optimistic locking are supported for selected entities by means of specified lock modes. Optimistic locking is described in sections 3.4.1 and 3.4.2; pessimistic locking in section 3.4.3. Section 3.4.4 describes the setting of optimistic and pessimistic lock modes. The
configuration of the setting of optimistic lock modes is described in section 3.4.4.1, and the configuration of the setting of pessimistic lock modes is described in section 3.4.4.2.
[31] These are instances that were persistent in the database at the start of the transaction.
[32] It is unspecified as to whether instances that were not persistent in the database behave as new instances or detached instances
after rollback. This may be implementation-dependent.
[33] Applications may require that database isolation levels higher than read-committed be in effect. The configuration of the setting
database isolation levels, however, is outside the scope of this specification.
JSR-338 Final Release
89
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Locking and Concurrency
3.4.1 Optimistic Locking
Optimistic locking is a technique that is used to insure that updates to the database data corresponding
to the state of an entity are made only when no intervening transaction has updated that data since the
entity state was read. This insures that updates or deletes to that data are consistent with the current
state of the database and that intervening updates are not lost. Transactions that would cause this constraint to be violated result in an OptimisticLockException being thrown and the transaction
marked for rollback.
Portable applications that wish to enable optimistic locking for entities must specify Version
attributes for those entities—i.e., persistent properties or fields annotated with the Version annotation
or specified in the XML descriptor as version attributes. Applications are strongly encouraged to enable
optimistic locking for all entities that may be concurrently accessed or that may be merged from a disconnected state. Failure to use optimistic locking may lead to inconsistent entity state, lost updates and
other state irregularities. If optimistic locking is not defined as part of the entity state, the application
must bear the burden of maintaining data consistency.
3.4.2 Version Attributes
The Version field or property is used by the persistence provider to perform optimistic locking. It is
accessed and/or set by the persistence provider in the course of performing lifecycle operations on the
entity instance. An entity is automatically enabled for optimistic locking if it has a property or field
mapped with a Version mapping.
An entity may access the state of its version field or property or export a method for use by the application to access the version, but must not modify the version value[34]. With the exception noted in section 4.10, only the persistence provider is permitted to set or update the value of the version attribute in
the object.
The version attribute is updated by the persistence provider runtime when the object is written to the
database. All non-relationship fields and properties and all relationships owned by the entity are
included in version checks[35].
The persistence provider's implementation of the merge operation must examine the version attribute
when an entity is being merged and throw an OptimisticLockException if it is discovered that
the object being merged is a stale copy of the entity—i.e. that the entity has been updated since the
entity became detached. Depending on the implementation strategy used, it is possible that this exception may not be thrown until flush is called or commit time, whichever happens first.
The persistence provider runtime is required to use only the version attribute when performing optimistic lock checking. Persistence provider implementations may provide additional mechanisms beside
version attributes to enable optimistic lock checking. However, support for such mechanisms is not
required of an implementation of this specification.[36]
[34] Bulk update statements, however, are permitted to set the value of version attributes. See section 4.10.
[35] This includes owned relationships maintained in join tables.
[36] Such additional mechanisms may be standardized by a future release of this specification.
4/2/13
90
JSR-338 Final Release
Oracle
Locking and Concurrency
Java Persistence 2.1, Final Release
Entity Operations
If only some entities contain version attributes, the persistence provider runtime is required to check
those entities for which version attributes have been specified. The consistency of the object graph is
not guaranteed, but the absence of version attributes on some of the entities will not stop operations
from completing.
3.4.3 Pessimistic Locking
While optimistic locking is typically appropriate in dealing with moderate contention among concurrent
transactions, in some applications it may be useful to immediately obtain long-term database locks for
selected entities because of the often late failure of optimistic transactions. Such immediately obtained
long-term database locks are referred to here as “pessimistic” locks.[37]
Pessimistic locking guarantees that once a transaction has obtained a pessimistic lock on an entity
instance:
• no other transaction (whether a transaction of an application using the Java Persistence API or
any other transaction using the underlying resource) may successfully modify or delete that
instance until the transaction holding the lock has ended.
• if the pessimistic lock is an exclusive lock[38], that same transaction may modify or delete that
entity instance.
When an entity instance is locked using pessimistic locking, the persistence provider must lock the database row(s) that correspond to the non-collection-valued persistent state of that instance. If a joined
inheritance strategy is used, or if the entity is otherwise mapped to a secondary table, this entails locking
the row(s) for the entity instance in the additional table(s). Entity relationships for which the locked
entity contains the foreign key will also be locked, but not the state of the referenced entities (unless
those entities are explicitly locked). Element collections and relationships for which the entity does not
contain the foreign key (such as relationships that are mapped to join tables or unidirectional
one-to-many relationships for which the target entity contains the foreign key) will not be locked by
default.
Element collections and relationships owned by the entity that are contained in join tables will be
locked if the javax.persistence.lock.scope property is specified with a value of
PessimisticLockScope.EXTENDED. The state of entities referenced by such relationships will
not be locked (unless those entities are explicitly locked). This property may be passed as an argument
to the methods of the EntityManager, Query, and TypedQuery interfaces that allow lock modes
to be specified or used with the NamedQuery annotation.
Locking such a relationship or element collection generally locks only the rows in the join table or collection table for that relationship or collection. This means that phantoms will be possible.
[37] Implementations are permitted to use database mechanisms other than locking to achieve the semantic effects described here, for
example, multiversion concurrency control mechanisms.
[38] This is achieved by using a lock with LockModeType.PESSIMISTIC_WRITE or LockModeType.PESSIMISTIC_FORCE_INCREMENT as described in section 3.4.4.
JSR-338 Final Release
91
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Locking and Concurrency
The values of the javax.persistence.lock.scope property are defined by the PessimisticLockScope enum.
package javax.persistence;
public enum PessimisticLockScope {
NORMAL,
EXTENDED
}
This specification does not define the mechanisms a persistence provider uses to obtain database locks,
and a portable application should not rely on how pessimistic locking is achieved on the database.[39] In
particular, a persistence provider or the underlying database management system may lock more rows
than the ones selected by the application.
Whenever a pessimistically locked entity containing a version attribute is updated on the database, the
persistence provider must also update (increment) the entity's version column to enable correct interaction with applications using optimistic locking. See sections 3.4.2 and 3.4.4.
Pessimistic locking may be applied to entities that do not contain version attributes. However, in this
case correct interaction with applications using optimistic locking cannot be ensured.
3.4.4 Lock Modes
Lock modes are intended to provide a facility that enables the effect of “repeatable read” semantics for
the items read, whether “optimistically” (as described in section 3.4.4.1) or “pessimistically” (as
described in section 3.4.4.2).
Lock modes can be specified by means of the EntityManager lock method, the methods of the EntityManager, Query, and TypedQuery interfaces that allow lock modes to be specified, and the
NamedQuery annotation.
Lock mode values are defined by the LockModeType enum. Six distinct lock modes are defined. The
lock mode type values READ and WRITE are synonyms of OPTIMISTIC and
OPTIMISTIC_FORCE_INCREMENT respectively.[40] The latter are to be preferred for new applications.
[39] For example, a persistence provider may use an underlying database platform's SELECT FOR UPDATE statements to implement
pessimistic locking if that construct provides appropriate semantics, or the provider may use an isolation level of repeatable read.
[40] The lock mode type NONE may be specified as a value of lock mode arguments and also provides a default value for annotations.
4/2/13
92
JSR-338 Final Release
Oracle
Locking and Concurrency
Java Persistence 2.1, Final Release
Entity Operations
package javax.persistence;
public enum LockModeType {
READ,
WRITE,
OPTIMISTIC,
OPTIMISTIC_FORCE_INCREMENT,
PESSIMISTIC_READ,
PESSIMISTIC_WRITE,
PESSIMISTIC_FORCE_INCREMENT,
NONE
}
3.4.4.1 OPTIMISTIC, OPTIMISTIC_FORCE_INCREMENT
The lock modes OPTIMISTIC and OPTIMISTIC_FORCE_INCREMENT are used for optimistic
locking. The lock mode type values READ and WRITE are synonymous with OPTIMISTIC and
OPTIMISTIC_FORCE_INCREMENT respectively.
The semantics of requesting locks of type LockModeType.OPTIMISTIC and LockModeType.OPTIMISTIC_FORCE_INCREMENT are the following.
If transaction T1 calls lock(entity, LockModeType.OPTIMISTIC) on a versioned object, the
entity manager must ensure that neither of the following phenomena can occur:
• P1 (Dirty read): Transaction T1 modifies a row. Another transaction T2 then reads that row and
obtains the modified value, before T1 has committed or rolled back. Transaction T2 eventually
commits successfully; it does not matter whether T1 commits or rolls back and whether it does
so before or after T2 commits.
• P2 (Non-repeatable read): Transaction T1 reads a row. Another transaction T2 then modifies or
deletes that row, before T1 has committed. Both transactions eventually commit successfully.
This will generally be achieved by the entity manager acquiring a lock on the underlying database row.
While with optimistic concurrency concurrency, long-term database read locks are typically not
obtained immediately, a compliant implementation is permitted to obtain an immediate lock (so long as
it is retained until commit completes). If the lock is deferred until commit time, it must be retained until
the commit completes. Any implementation that supports repeatable reads in a way that prevents the
above phenomena is permissible.
The persistence implementation is not required to support calling lock(entity, LockModeType.OPTIMISTIC) on a non-versioned object. When it cannot support such a lock call, it must
throw the PersistenceException. When supported, whether for versioned or non-versioned
objects, LockModeType.OPTIMISTIC must always prevent the phenomena P1 and P2. Applications that call lock(entity, LockModeType.OPTIMISTIC) on non-versioned objects will not
be portable.
JSR-338 Final Release
93
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Locking and Concurrency
If transaction T1 calls lock(entity, LockModeType.OPTIMISTIC_FORCE_INCREMENT)
on a versioned object, the entity manager must avoid the phenomena P1 and P2 (as with LockModeType.OPTIMISTIC) and must also force an update (increment) to the entity's version column. A
forced version update may be performed immediately, or may be deferred until a flush or commit. If an
entity is removed before a deferred version update was to have been applied, the forced version update
is omitted.
The persistence implementation is not required to support calling lock(entity, LockModeType.OPTIMISTIC_FORCE_INCREMENT) on a non-versioned object. When it cannot support
such a lock call, it must throw the PersistenceException. When supported, whether for versioned or non-versioned objects, LockModeType.OPTIMISTIC_FORCE_INCREMENT must
always prevent the phenomena P1 and P2. For non-versioned objects, whether or not LockModeType.OPTIMISTIC_FORCE_INCREMENT has any additional behavior is vendor-specific. Applications that call lock(entity,
LockModeType.OPTIMISTIC_FORCE_INCREMENT) on
non-versioned objects will not be portable.
For versioned objects, it is permissible for an implementation to use LockModeType.OPTIMISTIC_FORCE_INCREMENT where LockModeType.OPTIMISTIC was requested,
but not vice versa.
If a versioned object is otherwise updated or removed, then the implementation must ensure that the
requirements of LockModeType.OPTIMISTIC_FORCE_INCREMENT are met, even if no explicit
call to EntityManager.lock was made.
For portability, an application should not depend on vendor-specific hints or configuration to ensure
repeatable read for objects that are not updated or removed via any mechanism other than the use of version attributes and the EntityManager lock method. However, it should be noted that if an implementation has acquired up-front pessimistic locks on some database rows, then it is free to ignore
lock(entity, LockModeType.OPTIMISTIC) calls on the entity objects representing those
rows.
3.4.4.2 PESSIMISTIC_READ, PESSIMISTIC_WRITE,
PESSIMISTIC_FORCE_INCREMENT
The
lock
modes
PESSIMISTIC_READ,
PESSIMISTIC_WRITE,
and
PESSIMISTIC_FORCE_INCREMENT are used to immediately obtain long-term database locks.[41]
The semantics of requesting locks of type LockModeType.PESSIMISTIC_READ, LockModeType.PESSIMISTIC_WRITE, and LockModeType.PESSIMISTIC_FORCE_INCREMENT are
the following.
If transaction T1 calls lock(entity,
LockModeType.PESSIMISTIC_READ) or
lock(entity, LockModeType.PESSIMISTIC_WRITE)on an object, the entity manager must
ensure that neither of the following phenomena can occur:
[41] Databases concurrency control mechanisms that provide comparable semantics, e.g., multiversion concurrency control, can be
used by the provider.
4/2/13
94
JSR-338 Final Release
Oracle
Locking and Concurrency
Java Persistence 2.1, Final Release
Entity Operations
• P1 (Dirty read): Transaction T1 modifies a row. Another transaction T2 then reads that row and
obtains the modified value, before T1 has committed or rolled back.
• P2 (Non-repeatable read): Transaction T1 reads a row. Another transaction T2 then modifies or
deletes that row, before T1 has committed or rolled back.
Any such lock must be obtained immediately and retained until transaction T1 completes (commits or
rolls back).
Avoidance of phenomena P1 and P2 is generally achieved by the entity manager acquiring a long-term
lock on the underlying database row(s). Any implementation that supports pessimistic repeatable reads
as described above is permissible.
A lock with LockModeType.PESSIMISTIC_WRITE can be obtained on an entity instance
to force serialization among transactions attempting to update the entity data. A lock with
LockModeType.PESSIMISTIC_READ can be used to query data using repeatable-read
semantics without the need to reread the data at the end of the transaction to obtain a lock, and
without blocking other transactions reading the data. A lock with LockModeType.PESSIMISTIC_WRITE can be used when querying data and there is a high likelihood of deadlock or update failure among concurrent updating transactions.
The persistence implementation must support calling lock(entity, LockModeType.PESSIMISTIC_READ) and lock(entity, LockModeType.PESSIMISTIC_WRITE)on a non-versioned entity as well as on a versioned entity.
It is permissible for an implementation to use LockModeType.PESSIMISTIC_WRITE where
LockModeType.PESSIMISTIC_READ was requested, but not vice versa.
When the lock cannot be obtained, and the database locking failure results in transaction-level rollback,
the provider must throw the PessimisticLockException and ensure that the JTA transaction or
EntityTransaction has been marked for rollback.
When the lock cannot be obtained, and the database locking failure results in only statement-level rollback, the provider must throw the LockTimeoutException (and must not mark the transaction for
rollback).
When an application locks an entity with LockModeType.PESSIMISTIC_READ and later updates
that entity, the lock must be converted to an exclusive lock when the entity is flushed to the database[42].
If the lock conversion fails, and the database locking failure results in transaction-level rollback, the
provider must throw the PessimisticLockException and ensure that the JTA transaction or
EntityTransaction has been marked for rollback. When the lock conversion fails, and the database locking failure results in only statement-level rollback, the provider must throw the LockTimeoutException (and must not mark the transaction for rollback).
[42] The persistence provider is not required to flush the entity to the database immediately.
JSR-338 Final Release
95
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Locking and Concurrency
When lock(entity, LockModeType.PESSIMISTIC_READ), lock(entity, LockModeType.PESSIMISTIC_WRITE), or lock(entity, LockModeType.PESSIMISTIC_FORCE_INCREMENT)is invoked on a versioned entity that is already in the persistence context, the
provider must also perform optimistic version checks when obtaining the lock. An OptimisticLockException must be thrown if the version checks fail. Depending on the implementation strategy used by the provider, it is possible that this exception may not be thrown until flush is called or
commit time, whichever occurs first.
If transaction T1 calls lock(entity, LockModeType.PESSIMISTIC_FORCE_INCREMENT)
on a versioned object, the entity manager must avoid the phenomenon P1 and P2 (as with LockModeType.PESSIMISTIC_READ and LockModeType.PESSIMISTIC_WRITE) and must also force
an update (increment) to the entity's version column.
The persistence implementation is not required to support calling lock(entity, LockModeType.PESSIMISTIC_FORCE_INCREMENT) on a non-versioned object. When it cannot support
such a lock call, it must throw the PersistenceException. When supported, whether for versioned or non-versioned objects, LockModeType.PESSIMISTIC_FORCE_INCREMENT must
always prevent the phenomena P1 and P2. For non-versioned objects, whether or not LockModeType.PESSIMISTIC_FORCE_INCREMENT has any additional behavior is vendor-specific. Applications that call lock(entity, LockModeType.PESSIMISTIC_FORCE_INCREMENT) on
non-versioned objects will not be portable.
For versioned objects, it is permissible for an implementation to use LockModeType.PESSIMISTIC_FORCE_INCREMENT where LockModeType.PESSIMISTIC_READ or
LockModeType.PESSIMISTIC_WRITE was requested, but not vice versa.
If a versioned object locked with LockModeType.PESSIMISTIC_READ or LockModeType.PESSIMISTIC_WRITE is updated, then the implementation must ensure that the requirements
of LockModeType.PESSIMISTIC_FORCE_INCREMENT are met.
3.4.4.3 Lock Mode Properties and Uses
The following property is defined by this specification for use in pessimistic locking, as described in
section 3.4.3:
javax.persistence.lock.scope
This property may be used with the methods of the EntityManager interface that allow lock modes
to be specified, the Query and TypedQuery setLockMode methods, and the NamedQuery annotation. When specified, this property must be observed. The provider is permitted to lock more (but not
fewer) rows than requested.
The following hint is defined by this specification for use in pessimistic locking.
javax.persistence.lock.timeout // time in milliseconds
4/2/13
96
JSR-338 Final Release
Oracle
Locking and Concurrency
Java Persistence 2.1, Final Release
Entity Operations
This hint may be used with the methods of the EntityManager interface that allow lock modes to be
specified, the Query.setLockMode method and the NamedQuery annotation. It may also be
passed as a property to the Persistence.createEntityManagerFactory method and used
in the properties element of the persistence.xml file. See sections 3.1.1, 3.10.9, 8.2.1.9, 9.7,
and 10.4.1. When used in the createEntityManagerFactory method, the persistence.xml file, and the NamedQuery annotation, the timeout hint serves as a default value which
can be selectively overridden by use in the methods of the EntityManager, Query, and
TypedQuery interfaces as specified above. When this hint is not specified, database timeout values
are assumed to apply.
A timeout value of 0 is used to specify “no wait” locking.
Portable applications should not rely on this hint. Depending on the database in use and the locking
mechanisms used by the persistence provider, the hint may or may not be observed.
Vendors are permitted to support the use of additional, vendor-specific locking hints. Vendor-specific
hints must not use the javax.persistence namespace. Vendor-specific hints must be ignored if
they are not understood.
If the same property or hint is specified more than once, the following order of overriding applies, in
order of decreasing precedence:
• argument to method of EntityManager, Query, or TypedQuery interface
• specification to NamedQuery (annotation or XML)
• argument to createEntityManagerFactory method
• specification in persistence.xml
3.4.5 OptimisticLockException
Provider implementations may defer writing to the database until the end of the transaction, when consistent with the lock mode and flush mode settings in effect. In this case, an optimistic lock check may
not occur until commit time, and the OptimisticLockException may be thrown in the “before
completion” phase of the commit. If the OptimisticLockException must be caught or handled
by the application, the flush method should be used by the application to force the database writes to
occur. This will allow the application to catch and handle optimistic lock exceptions.
The OptimisticLockException provides an API to return the object that caused the exception to
be thrown. The object reference is not guaranteed to be present every time the exception is thrown but
should be provided whenever the persistence provider can supply it. Applications cannot rely upon this
object being available.
In some cases an OptimisticLockException will be thrown and wrapped by another exception,
such as a RemoteException, when VM boundaries are crossed. Entities that may be referenced in
wrapped exceptions should implement Serializable so that marshalling will not fail.
An OptimisticLockException always causes the transaction to be marked for rollback.
JSR-338 Final Release
97
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Entity Listeners and Callback Methods
Refreshing objects or reloading objects in a new transaction context and then retrying the transaction is
a potential response to an OptimisticLockException.
3.5 Entity Listeners and Callback Methods
A method may be designated as a lifecycle callback method to receive notification of entity lifecycle
events. A lifecycle callback method can be defined on an entity class, a mapped superclass, or an entity
listener class associated with an entity or mapped superclass. An entity listener class is a class whose
methods are invoked in response to lifecycle events on an entity. Any number of entity listener classes
can be defined for an entity class or mapped superclass.
Default entity listeners—entity listener classes whose callback methods apply to all entities in the persistence unit—can be specified by means of the XML descriptor.
Lifecycle callback methods and entity listener classes are defined by means of metadata annotations or
the XML descriptor. When annotations are used, one or more entity listener classes are denoted using
the EntityListeners annotation on the entity class or mapped superclass. If multiple entity listeners are defined, the order in which they are invoked is determined by the order in which they are specified in the EntityListeners annotation. The XML descriptor may be used as an alternative to
specify the invocation order of entity listeners or to override the order specified in metadata annotations.
Any subset or combination of annotations may be specified on an entity class, mapped superclass, or
listener class. A single class must not have more than one lifecycle callback method for the same lifecycle event. The same method may be used for multiple callback events.
Multiple entity classes and mapped superclasses in an inheritance hierarchy may define listener classes
and/or lifecycle callback methods directly on the class. Section 3.5.5 describes the rules that apply to
method invocation order in this case.
3.5.1 Entity Listeners
The entity listener class must have a public no-arg constructor.
Entity listener classes in Java EE environments support dependency injection through the Contexts and
Dependency Injection API (CDI) [ 10 ] when CDI is enabled[43]. An entity listener class that makes use
of CDI injection may also define lifecycle callback methods annotated with the PostConstruct and
PreDestroy annotations. These methods will be invoked after injection has taken place and before
the entity listener instance is destroyed respectively.
The persistence provider is responsible for using the CDI SPI to create instances of the entity listener
class; to perform injection upon such instances; to invoke their PostConstruct and PreDestroy
methods, if any; and to dispose of the entity listener instances.
[43] CDI is enabled by default in Java EE 7. See the Java EE 7 specification [ 9 ].
4/2/13
98
JSR-338 Final Release
Oracle
Entity Listeners and Callback Methods
Java Persistence 2.1, Final Release
Entity Operations
The persistence provider is only required to support CDI injection into entity listeners in Java EE container environments[44]. If the CDI is not enabled, the persistence provider must not invoke entity listeners that depend upon CDI injection.
An entity listener is a noncontextual object. In supporting injection into entity listeners, the persistence
provider must behave as if it carries out the following steps involving the use of the CDI SPI. (See [10]
and [11]).
• Obtain a BeanManager instance. (See section 9.1.)
• Create an AnnotatedType instance for the entity listener class.
• Create an InjectionTarget instance for the annotated type.
• Create a CreationalContext.
• Instantiate the listener by calling the InjectionTarget produce method.
• Inject the listener instance by calling the InjectionTarget inject method on the
instance.
• Invoke the PostConstruct callback, if any, by calling the InjectionTarget postConstruct method on the instance.
When the listener instance is to be destroyed, the persistence provider must behave as if it carries out the
following steps.
• Call the InjectionTarget preDestroy method on the instance.
• Call the InjectionTarget dispose method on the instance
• Call the CreationalContext release method.
Persistence providers may optimize the steps above, e.g. by avoiding calls to the actual CDI SPI and
relying on container-specific interfaces instead, as long as the outcome is the same.
Entity listeners that do not make use of CDI injection are stateless. The lifecycle of such entity listeners
is unspecified.
When invoked from within a Java EE environment, the callback listeners for an entity share the enterprise naming context of the invoking component, and the entity callback methods are invoked in the
transaction and security contexts of the calling component at the time at which the callback method is
invoked. [45]
[44] The persistence provider may support CDI injection into entity listeners in other environments in which the BeanManager is
available.
[45] For example, if a transaction commit occurs as a result of the normal termination of a session bean business method with transaction attribute RequiresNew, the PostPersist and PostRemove callbacks are executed in the naming context, the transaction context, and the security context of that component.
JSR-338 Final Release
99
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Entity Listeners and Callback Methods
3.5.2 Lifecycle Callback Methods
Entity lifecycle callback methods can be defined on an entity listener class and/or directly on an entity
class or mapped superclass.
Lifecycle callback methods are annotated with annotations designating the callback events for which
they are invoked or are mapped to the callback event using the XML descriptor.
The annotations (and XML elements) used for callback methods on the entity class or mapped superclass and for callback methods on the entity listener class are the same. The signatures of individual
methods, however, differ.
Callback methods defined on an entity class or mapped superclass have the following signature:
void <METHOD>()
Callback methods defined on an entity listener class have the following signature:
void <METHOD>(Object)
The Object argument is the entity instance for which the callback method is invoked. It may be
declared as the actual entity type.
The callback methods can have public, private, protected, or package level access, but must not be
static or final.
The following annotations designate lifecycle event callback methods of the corresponding types.
• PrePersist
• PostPersist
• PreRemove
• PostRemove
• PreUpdate
• PostUpdate
• PostLoad
The following rules apply to lifecycle callback methods:
• Lifecycle callback methods may throw unchecked/runtime exceptions. A runtime exception
thrown by a callback method that executes within a transaction causes that transaction to be
marked for rollback if the persistence context is joined to the transaction.
• Lifecycle callbacks can invoke JNDI, JDBC, JMS, and enterprise beans.
4/2/13
100
JSR-338 Final Release
Oracle
Entity Listeners and Callback Methods
Java Persistence 2.1, Final Release
Entity Operations
• In general, the lifecycle method of a portable application should not invoke EntityMan-
ager or query operations, access other entity instances, or modify relationships within the
same persistence context[46].[47] A lifecycle callback method may modify the non-relationship
state of the entity on which it is invoked.
3.5.3 Semantics of the Life Cycle Callback Methods for Entities
The PrePersist and PreRemove callback methods are invoked for a given entity before the
respective EntityManager persist and remove operations for that entity are executed. For entities to
which the merge operation has been applied and causes the creation of newly managed instances, the
PrePersist callback methods will be invoked for the managed instance after the entity state has
been copied to it. These PrePersist and PreRemove callbacks will also be invoked on all entities
to which these operations are cascaded. The PrePersist and PreRemove methods will always be
invoked as part of the synchronous persist, merge, and remove operations.
The PostPersist and PostRemove callback methods are invoked for an entity after the entity has
been made persistent or removed. These callbacks will also be invoked on all entities to which these
operations are cascaded. The PostPersist and PostRemove methods will be invoked after the
database insert and delete operations respectively. These database operations may occur directly after
the persist, merge, or remove operations have been invoked or they may occur directly after a flush
operation has occurred (which may be at the end of the transaction). Generated primary key values are
available in the PostPersist method.
The PreUpdate and PostUpdate callbacks occur before and after the database update operations to
entity data respectively. These database operations may occur at the time the entity state is updated or
they may occur at the time state is flushed to the database (which may be at the end of the transaction).
Note that it is implementation-dependent as to whether PreUpdate and PostUpdate callbacks occur when an entity is persisted and subsequently modified in a single transaction or
when an entity is modified and subsequently removed within a single transaction. Portable
applications should not rely on such behavior.
The PostLoad method for an entity is invoked after the entity has been loaded into the current persistence context from the database or after the refresh operation has been applied to it. The PostLoad
method is invoked before a query result is returned or accessed or before an association is traversed.
It is implementation-dependent as to whether callback methods are invoked before or after the cascading of the lifecycle events to related entities. Applications should not depend on this ordering.
[46] Note that this caution applies also to the actions of objects that might be injected into an entity listener.
[47] The semantics of such operations may be standardized in a future release of this specification.
JSR-338 Final Release
101
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Entity Listeners and Callback Methods
3.5.4 Example
@Entity
@EntityListeners(com.acme.AlertMonitor.class)
public class Account {
Long accountId;
Integer balance;
boolean preferred;
@Id
public Long getAccountId() { ... }
...
public Integer getBalance() { ... }
...
@Transient // because status depends upon non-persistent context
public boolean isPreferred() { ... }
...
public void deposit(Integer amount) { ... }
public Integer withdraw(Integer amount) throws NSFException {... }
@PrePersist
protected void validateCreate() {
if (getBalance() < MIN_REQUIRED_BALANCE)
throw new AccountException("Insufficient balance to open an
account");
}
@PostLoad
protected void adjustPreferredStatus() {
preferred =
(getBalance() >= AccountManager.getPreferredStatusLevel());
}
}
public class AlertMonitor {
@PostPersist
public void newAccountAlert(Account acct) {
Alerts.sendMarketingInfo(acct.getAccountId(), acct.getBalance());
}
}
3.5.5 Multiple Lifecycle Callback Methods for an Entity Lifecycle Event
If multiple callback methods are defined for an entity lifecycle event, the ordering of the invocation of
these methods is as follows.
Default listeners, if any, are invoked first, in the order specified in the XML descriptor. Default listeners
apply to all entities in the persistence unit, unless explicitly excluded by means of the ExcludeDefaultListeners annotation or exclude-default-listeners XML element.
4/2/13
102
JSR-338 Final Release
Oracle
Entity Listeners and Callback Methods
Java Persistence 2.1, Final Release
Entity Operations
The lifecycle callback methods defined on the entity listener classes for an entity class or mapped superclass are invoked in the same order as the specification of the entity listener classes in the EntityListeners annotation.
If multiple classes in an inheritance hierarchy—entity classes and/or mapped superclasses—define
entity listeners, the listeners defined for a superclass are invoked before the listeners defined for its subclasses in this order. The ExcludeSuperclassListeners annotation or exclude-superclass-listeners XML element may be applied to an entity class or mapped superclass to exclude
the invocation of the listeners defined by the entity listener classes for the superclasses of the entity or
mapped superclass. The excluded listeners are excluded from the class to which the ExcludeSuperclassListeners annotation or element has been specified and its subclasses.[48] The ExcludeSuperclassListeners annotation (or exclude-superclass-listeners XML element)
does not cause default entity listeners to be excluded from invocation.
If a lifecycle callback method for the same lifecycle event is also specified on the entity class and/or one
or more of its entity or mapped superclasses, the callback methods on the entity class and/or superclasses are invoked after the other lifecycle callback methods, most general superclass first. A class is
permitted to override an inherited callback method of the same callback type, and in this case, the overridden method is not invoked.[49]
Callback methods are invoked by the persistence provider runtime in the order specified. If the callback
method execution terminates normally, the persistence provider runtime then invokes the next callback
method, if any.
The XML descriptor may be used to override the lifecycle callback method invocation order specified
in annotations.
3.5.6 Example
There are several entity classes and listeners for animals:
@Entity
public class Animal {
....
@PostPersist
protected void postPersistAnimal() {
....
}
}
@Entity
@EntityListeners(PetListener.class)
public class Pet extends Animal {
....
}
[48] Excluded listeners may be reintroduced on an entity class by listing them explicitly in the EntityListeners annotation or
XML entity-listeners element.
[49] If a method overrides an inherited callback method but specifies a different lifecycle event or is not a lifecycle callback method,
the overridden method will not be invoked.
JSR-338 Final Release
103
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Entity Listeners and Callback Methods
@Entity
@EntityListeners({CatListener.class, CatListener2.class})
public class Cat extends Pet {
....
}
public class PetListener {
@PostPersist
protected void postPersistPetListenerMethod(Object pet) {
....
}
}
public class CatListener {
@PostPersist
protected void postPersistCatListenerMethod(Object cat) {
....
}
}
public class CatListener2 {
@PostPersist
protected void postPersistCatListener2Method(Object cat) {
....
}
}
If a PostPersist event occurs on an instance of Cat, the following methods are called in order:
postPersistPetListenerMethod
postPersistCatListenerMethod
postPersistCatListener2Method
postPersistAnimal
Assume that SiameseCat is defined as a subclass of Cat:
@EntityListeners(SiameseCatListener.class)
@Entity
public class SiameseCat extends Cat {
...
@PostPersist
protected void postPersistSiameseCat() {
...
}
}
public class SiameseCatListener {
@PostPersist
protected void postPersistSiameseCatListenerMethod(Object cat) {
....
}
}
4/2/13
104
JSR-338 Final Release
Oracle
Entity Listeners and Callback Methods
Java Persistence 2.1, Final Release
Entity Operations
If a PostPersist event occurs on an instance of SiameseCat, the following methods are called in
order:
postPersistPetListenerMethod
postPersistCatListenerMethod
postPersistCatListener2Method
postPersistSiameseCatListenerMethod
postPersistAnimal
postPersistSiameseCat
Assume the definition of SiameseCat were instead:
@EntityListeners(SiameseCatListener.class)
@Entity
public class SiameseCat extends Cat {
...
@PostPersist
protected void postPersistAnimal() {
...
}
}
In this case, the following methods would be called in order, where postPersistAnimal is the
PostPersist method defined in the SiameseCat class:
postPersistPetListenerMethod
postPersistCatListenerMethod
postPersistCatListener2Method
postPersistSiameseCatListenerMethod
postPersistAnimal
3.5.7 Exceptions
Lifecycle callback methods may throw runtime exceptions. A runtime exception thrown by a callback
method that executes within a transaction causes that transaction to be marked for rollback if the persistence context is joined to the transaction. No further lifecycle callback methods will be invoked after a
runtime exception is thrown.
3.5.8 Specification of Callback Listener Classes and Lifecycle Methods in the XML
Descriptor
The XML descriptor can be used as an alternative to metadata annotations to specify entity listener
classes and their binding to entities or to override the invocation order of lifecycle callback methods as
specified in annotations.
3.5.8.1 Specification of Callback Listeners
The entity-listener XML descriptor element is used to specify the lifecycle listener methods of
an entity listener class. The lifecycle listener methods are specified by using the pre-persist,
post-persist, pre-remove, post-remove, pre-update, post-update, and/or
post-load elements.
JSR-338 Final Release
105
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Bean Validation
An entity listener class can define multiple callback methods. However, at most one method of an entity
listener class can be designated as a pre-persist method, post-persist method, pre-remove method,
post-remove method, pre-update method, post-update method, and/or post-load method, regardless of
whether the XML descriptor is used to define entity listeners or whether some combination of annotations and XML descriptor elements is used.
3.5.8.2 Specification of the Binding of Entity Listener Classes to Entities
The entity-listeners subelement of the persistence-unit-defaults element is used to
specify the default entity listeners for the persistence unit.
The entity-listeners subelement of the entity or mapped-superclass element is used to
specify the entity listener classes for the respective entity or mapped superclass and its subclasses.
The binding of entity listeners to entity classes is additive. The entity listener classes bound to the
superclasses of an entity or mapped superclass are applied to it as well.
The exclude-superclass-listeners element specifies that the listener methods for superclasses are not to be invoked for an entity class (or mapped superclass) and its subclasses.
The exclude-default-listeners element specifies that default entity listeners are not to be
invoked for an entity class (or mapped superclass) and its subclasses.
Explicitly listing an excluded default or superclass listener for a given entity class or mapped superclass
causes it to be applied to that entity or mapped superclass and its subclasses.
In the case of multiple callback methods for a single lifecycle event, the invocation order rules
described in section 3.5.5 apply.
3.6 Bean Validation
This specification defines support for use of Bean Validation[8] within Java Persistence applications.
Managed classes (entities, mapped superclasses, and embeddable classes) may be configured to include
Bean Validation constraints.
Automatic validation using these constraints is achieved by specifying that Java Persistence delegate
validation to the Bean Validation implementation upon the pre-persist, pre-update, and pre-remove
entity lifecycle events described in Section 3.5.3.
Validation can also be achieved by the application calling the validate method of a Validator
instance upon an instance of a managed class, as described in the Bean Validation specification [8].
4/2/13
106
JSR-338 Final Release
Oracle
Bean Validation
Java Persistence 2.1, Final Release
Entity Operations
3.6.1 Automatic Validation Upon Lifecycle Events
This specification supports the use of bean validation for the automatic validation of entities upon the
pre-persist, pre-update, and pre-remove lifecycle validation events. These lifecycle validation events
occur immediately after the point at which all the PrePersist, PreUpdate, and PreRemove lifecycle callback method invocations respectively have been completed, or immediately after the point at
which such lifecycle callback methods would have been completed (in the event that such callback
methods are not present).
In the case where an entity is persisted and subsequently modified in a single transaction or
when an entity is modified and subsequently removed in a single transaction, it is implementation dependent as to whether the pre-update validation event occurs. Portable applications
should not rely on this behavior.
3.6.1.1 Enabling Automatic Validation
The validation-mode element of the persistence.xml file determines whether the automatic
lifecycle event validation is in effect. The values of the validation-mode element are AUTO,
CALLBACK, NONE. The default validation mode is AUTO.
If the application creates the entity manager factory using the Persistence.createEntityManagerFactory method, the validation mode can be specified using the javax.persistence.validation.mode map key, which will override the value specified (or defaulted) in the
persistence.xml file. The map values for this key are "auto", "callback", "none".
If the auto validation mode is specified by the validation-mode element or the javax.persistence.validation.mode property, or if neither the validation-mode element nor the
javax.persistence.validation.mode property is specified, and a Bean Validation provider
is present in the environment, the persistence provider must perform the automatic validation of entities
as described in section 3.6.1.2. If no Bean Validation provider is present in the environment, no lifecycle event validation takes place.
If the callback validation mode is specified by the validation-mode element or the javax.persistence.validation.mode property, the persistence provider must perform the lifecycle event
validation as described in section 3.6.1.2. It is an error if there is no Bean Validation provider present in
the environment, and the provider must throw the PersistenceException if the javax.persistence.validation.mode property value "callback" has been passed to the Persistence.createEntityManagerFactory method.
If the none validation mode is specified by the validation-mode element or the javax.persistence.validation.mode property, the persistence provider must not perform lifecycle event
validation.
3.6.1.2 Requirements for Automatic Validation upon Lifecycle Events
For each event type, a list of groups is targeted for validation. By default, the default Bean Validation
group (the group Default) will be validated upon the pre-persist and pre-update lifecycle validation
events, and no group will be validated upon the pre-remove event.
JSR-338 Final Release
107
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Bean Validation
This default validation behavior can be overridden by specifying the target groups using the following
validation properties in the persistence.xml file or by passing these properties in the configuration of the entity manager factory through the createEntityManagerFactory method:
• javax.persistence.validation.group.pre-persist
• javax.persistence.validation.group.pre-update
• javax.persistence.validation.group.pre-remove
The value of a validation property must be a list of the targeted groups. A targeted group must be specified by its fully qualified class name. Names must be separated by a comma.
When one of the above events occurs for an entity, the persistence provider must validate that entity by
obtaining a Validator instance from the validator factory in use (see section 3.6.2) and invoking its
validate method with the targeted groups. If the list of targeted groups is empty, no validation is
performed. If the set of ConstraintViolation objects returned by the validate method is not
empty, the persistence provider must throw the javax.validation.ConstraintViolationException containing a reference to the returned set of ConstraintViolation objects, and
must mark the transaction for rollback if the persistence context is joined to the transaction.
The validator instance that is used for automatic validation upon lifecycle events must use a TraversableResolver that has the following behavior:
• Attributes that have not been loaded must not be loaded.
• Validation cascade (@Valid) must not occur for entity associations (single- or multi-valued).
These requirements guarantee that no unloaded attribute or association will be loaded by side effect and
that no entity will be validated more than once during a given flush cycle.
Embeddable attributes must be validated only if the Valid annotation has been specified on them.
It is the responsibility of the persistence provider to pass an instance implementing the javax.validation.TraversableResolver interface to the Bean Validation provider by calling ValidatorFactory.usingContext().traversableResolver(tr).getValidator(), where
tr is the resolver having the behavior described above.
3.6.2 Providing the ValidatorFactory
In Java EE environments, a ValidatorFactory instance is made available by the Java EE container. The container is responsible for passing this validator factory to the persistence provider via the
map that is passed as an argument to the createContainerEntityManagerFactory call. The
map key used by the container must be the standard property name javax.persistence.validation.factory.
4/2/13
108
JSR-338 Final Release
Oracle
Entity Graphs
Java Persistence 2.1, Final Release
Entity Operations
In Java SE environments, the application can pass the ValidatorFactory instance via the map that
is passed as an argument to the Persistence.createEntityManagerFactory call. The map
key used must be the standard property name javax.persistence.validation.factory. If
no ValidatorFactory instance is provided by the application, and if a Bean Validation provider is
present in the classpath, the persistence provider must instantiate the ValidatorFactory using the
default bootstrapping approach defined by the Bean Validation specification [8], namely Validation.buildDefaultValidatorFactory().
3.7 Entity Graphs
An entity graph is a template that captures the path and boundaries for an operation or query. It is
defined in the form of metadata or an object created by the dynamic EntityGraph API.
Entity graphs are used in the specification of “fetch plans” for query or find operations.
The EntityGraph, AttributeNode, and Subgraph interfaces are used to dynamically construct
entity graphs. The annotations to statically define entity graphs, namely NamedEntityGraph,
NamedAttributeNode, and NamedSubgraph, are described in Section 10.3. The
named-entity-graph XML element and its subelements may be used to override these annotations or to define additional named entity graphs.
The semantics of entity graphs with regard to find and query operations are described in section 3.7.4.
JSR-338 Final Release
109
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Entity Graphs
3.7.1 EntityGraph Interface
package javax.persistence;
import javax.persistence.metamodel.Attribute;
import java.util.List;
/**
* This type represents the root of an entity graph that will be used
* as a template to define the attribute nodes and boundaries of a
* graph of entities and entity relationships. The root must be an
* entity type.
*
* The methods to add subgraphs implicitly create the corresponding
* attribute nodes as well; such attribute nodes should not be
* redundantly specified.
*
* @param <T> The type of the root entity.
*/
public interface EntityGraph<T> {
/**
* Return the name of a named EntityGraph (an entity graph
* defined by means of the NamedEntityGraph annotation,
* XML descriptor element, or added by means of the
* addNamedEntityGraph method. Returns null if the EntityGraph
* is not a named EntityGraph.
*/
public String getName();
/**
* Add one or more attribute nodes to the entity graph.
* @param attributeName name of the attribute
* @throws IllegalArgumentException if the attribute is not an
*
attribute of this entity.
* @throws IllegalStateException if the EntityGraph has been
*
statically defined
*/
public void addAttributeNodes(String ... attributeName);
/**
* Add one or more attribute nodes to the entity graph.
* @param attribute attribute
* @throws IllegalStateException if the EntityGraph has been
*
statically defined
*/
public void addAttributeNodes(Attribute<T, ?> ... attribute);
/**
* Add a node to the graph that corresponds to a managed
* type. This allows for construction of multi-node entity graphs
* that include related managed types.
* @param attribute attribute
* @return subgraph for the attribute
* @throws IllegalArgumentException if the attribute's target
*
type is not a managed type
* @throws IllegalStateException if the EntityGraph has been
*
statically defined
*/
public <X> Subgraph<X> addSubgraph(Attribute<T, X> attribute);
4/2/13
110
JSR-338 Final Release
Oracle
Entity Graphs
Java Persistence 2.1, Final Release
Entity Operations
/**
* Add a node to the graph that corresponds to a managed
* type with inheritance. This allows for multiple subclass
* subgraphs to be defined for this node of the entity
* graph. Subclass subgraphs will automatically include the
* specified attributes of superclass subgraphs.
* @param attribute attribute
* @param type entity subclass
* @return subgraph for the attribute
* @throws IllegalArgumentException if the attribute's target
*
type is not a managed type
* @throws IllegalStateException if the EntityGraph has been
*
statically defined
*/
public <X> Subgraph<? extends X>
addSubgraph(Attribute<T, X> attribute, Class<? extends X> type);
/**
* Add a node to the graph that corresponds to a managed
* type. This allows for construction of multi-node entity graphs
* that include related managed types.
* @param attributeName name of the attribute
* @return subgraph for the attribute
* @throws IllegalArgumentException if the attribute is not an
*
attribute of this entity.
* @throws IllegalArgumentException if the attribute's target
*
type is not a managed type
* @throws IllegalStateException if the EntityGraph has been
*
statically defined
*/
public <X> Subgraph<X> addSubgraph(String attributeName);
/**
* Add a node to the graph that corresponds to a managed
* type with inheritance. This allows for multiple subclass
* subgraphs to be defined for this node of the entity graph.
* Subclass subgraphs will automatically include the specified
* attributes of superclass subgraphs.
* @param attributeName name of the attribute
* @param type entity subclass
* @return subgraph for the attribute
* @throws IllegalArgumentException if the attribute is not an
*
attribute of this managed type.
* @throws IllegalArgumentException if the attribute's target
*
type is not a managed type
* @throws IllegalStateException if this EntityGraph has been
*
statically defined
*/
public <X> Subgraph<X> addSubgraph(String attributeName,
Class<X> type);
/**
* Add a node to the graph that corresponds to a map key
* that is a managed type. This allows for construction of
* multi-node entity graphs that include related managed types.
* @param attribute attribute
* @return subgraph for the key attribute
* @throws IllegalArgumentException if the attribute's target
JSR-338 Final Release
111
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
*
* @throws
*
*/
public <X>
Entity Graphs
type is not an entity
IllegalStateException if this EntityGraph has been
statically defined
Subgraph<X> addKeySubgraph(Attribute<T, X> attribute);
/**
* Add a node to the graph that corresponds to a map key
* that is a managed type with inheritance. This allows for
* construction of multi-node entity graphs that include related
* managed types. Subclass subgraphs will include the specified
* attributes of superclass subgraphs.
* @param attribute attribute
* @param type entity subclass
* @return subgraph for the key attribute
* @throws IllegalArgumentException if the attribute's target
*
type is not an entity
* @throws IllegalStateException if this EntityGraph has been
*
statically defined
*/
public <X> Subgraph<? extends X>
addKeySubgraph(Attribute<T, X> attribute,
Class<? extends X> type);
/**
* Add a node to the graph that corresponds to a map key
* that is a managed type. This allows for construction of
* multi-node entity graphs that include related managed types.
* @param attributeName name of the attribute
* @return subgraph for the key attribute
* @throws IllegalArgumentException if the attribute is not an
*
attribute of this entity.
* @throws IllegalArgumentException if the attribute's target
*
type is not an entity
* @throws IllegalStateException if this EntityGraph has been
*
statically defined
*/
public <X> Subgraph<X> addKeySubgraph(String attributeName);
/**
* Add a node to the graph that corresponds to a map key
* that is a managed type with inheritance. This allows for
* construction of multi-node entity graphs that include related
* managed types. Subclass subgraphs will automatically include
* the specified attributes of superclass subgraphs
* @param attributeName name of the attribute
* @param type entity subclass
* @return subgraph for the key attribute
* @throws IllegalArgumentException if the attribute is not an
*
attribute of this entity.
* @throws IllegalArgumentException if the attribute's target
*
type is not a managed type
* @throws IllegalStateException if this EntityGraph has been
*
statically defined
*/
public <X> Subgraph<X> addKeySubgraph(String attributeName,
Class<X> type);
4/2/13
112
JSR-338 Final Release
Oracle
Entity Graphs
Java Persistence 2.1, Final Release
Entity Operations
/**
* Add additional attributes to this entity graph that
* correspond to attributes of subclasses of this EntityGraph's
* entity type. Subclass subgraphs will automatically include
* the specified attributes of superclass subgraphs.
* @param type entity subclass
* @return subgraph for the subclass
* @throws IllegalArgumentException if the type is not an entity
type
* @throws IllegalStateException if the EntityGraph has been
*
statically defined
*/
public <T> Subgraph<? extends T>
addSubclassSubgraph(Class<? extends T> type);
}
/**
* Return the attribute nodes of this entity that are included
* in the entity graph.
* @return attribute nodes for the annotated entity type or
* empty list if none have been defined
*/
public List<AttributeNode<?>> getAttributeNodes();
3.7.2 AttributeNode Interface
package javax.persistence;
import java.util.Map;
/**
* Represents an attribute node of an entity graph.
*
* @param <T> The type of the attribute.
*/
public interface AttributeNode<T> {
/**
* Return the name of the attribute corresponding to the
* attribute node.
* @return name of the attribute
*/
public String getAttributeName();
/**
* Return the Map<Class, Subgraph> of subgraphs associated
* with this attribute node.
* @return Map of subgraphs associated with this attribute node
* or empty Map if none have been defined
*/
public Map<Class, Subgraph> getSubgraphs();
JSR-338 Final Release
113
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
}
Entity Graphs
/**
* Return the Map<Class, Subgraph> of subgraphs associated
* with this attribute node's map key.
* @return Map of subgraphs associated with this attribute
* node's map key or empty Map if none have been defined
*/
public Map<Class, Subgraph> getKeySubgraphs();
3.7.3 Subgraph Interface
package javax.persistence;
import javax.persistence.metamodel.Attribute;
import java.util.List;
/**
* This type represents a subgraph for an attribute node that
* corresponds to a Managed Type. Using this class, an entity
* subgraph can be embedded within an EntityGraph.
*
* @param <T> The type of the attribute.
*/
public interface Subgraph<T> {
/**
* Add one or more attribute nodes to the entity graph.
* @param attributeName name of the attribute
* @throws IllegalArgumentException if the attribute is not an
*
attribute of this managed type.
* @throws IllegalStateException if the EntityGraph has been
*
statically defined
*/
public void addAttributeNodes(String ... attributeName);
/**
* Add one or more attribute nodes to the entity graph.
* @param attribute attribute
* @throws IllegalStateException if this EntityGraph has been
*
statically defined
*/
public void addAttributeNodes(Attribute<T, ?> ... attribute);
/**
* Add a node to the graph that corresponds to a managed
* type. This allows for construction of multi-node entity
* graphs that include related managed types.
* @param attribute attribute
* @return subgraph for the attribute
* @throws IllegalArgumentException if the attribute's target
*
type is not a managed type
* @throws IllegalStateException if the EntityGraph has been
*
statically defined
*/
public <X> Subgraph<X> addSubgraph(Attribute<T, X> attribute);
4/2/13
114
JSR-338 Final Release
Oracle
Entity Graphs
Java Persistence 2.1, Final Release
Entity Operations
/**
* Add a node to the graph that corresponds to a managed
* type with inheritance. This allows for multiple subclass
* subgraphs to be defined for this node of the entity
* graph. Subclass subgraphs will automatically include the
* specified attributes of superclass subgraphs
* @param attribute attribute
* @param type entity subclass
* @return subgraph for the attribute
* @throws IllegalArgumentException if the attribute's target
*
type is not a managed type
* @throws IllegalStateException if this EntityGraph has been
*
statically defined
*/
public <X> Subgraph<? extends X>
addSubgraph(Attribute<T, X> attribute, Class<? extends X> type);
/**
* Add a node to the graph that corresponds to a managed
* type. This allows for construction of multi-node entity
* graphs that include related managed types.
* @param attributeName name of the attribute
* @return subgraph for the attribute
* @throws IllegalArgumentException if the attribute is not an
*
attribute of this managed type.
* @throws IllegalArgumentException if the attribute's target
*
type is not a managed type
* @throws IllegalStateException if this EntityGraph has been
*
statically defined
*/
public <X> Subgraph<X> addSubgraph(String attributeName);
/**
* Add a node to the graph that corresponds to a managed
* type with inheritance. This allows for multiple subclass
* subgraphs to be defined for this node of the entity
* graph. Subclass subgraphs will automatically include the
* specified attributes of superclass subgraphs
* @param attributeName name of the attribute
* @param type entity subclass
* @return subgraph for the attribute
* @throws IllegalArgumentException if the attribute is not
*
an attribute of this managed type.
* @throws IllegalArgumentException if the attribute's target
*
type is not a managed type
* @throws IllegalStateException if this EntityGraph has been
*
statically defined
*/
public <X> Subgraph<X> addSubgraph(String attributeName,
Class<X> type);
/**
* Add a node to the graph that corresponds to a map key
* that is a managed type. This allows for construction of
* multinode entity graphs that include related managed types.
* @param attribute attribute
* @return subgraph for the key attribute
* @throws IllegalArgumentException if the attribute's target
JSR-338 Final Release
115
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
*
* @throws
*
*/
public <X>
Entity Graphs
type is not a managed type entity
IllegalStateException if this EntityGraph has been
statically defined
Subgraph<X> addKeySubgraph(Attribute<T, X> attribute);
/**
* Add a node to the graph that corresponds to a map key
* that is a managed type with inheritance. This allows for
* construction of multi-node entity graphs that include related
* managed types. Subclass subgraphs will automatically include
* the specified attributes of superclass subgraphs
* @param attribute attribute
* @param type entity subclass
* @return subgraph for the attribute
* @throws IllegalArgumentException if the attribute's target
*
type is not a managed type entity
* @throws IllegalStateException if this EntityGraph has been
*
statically defined
*/
public <X> Subgraph<? extends X>
addKeySubgraph(Attribute<T, X> attribute, Class<? extends X> type);
/**
* Add a node to the graph that corresponds to a map key
* that is a managed type. This allows for construction of
* multi-node entity graphs that include related managed types.
* @param attributeName name of the attribute
* @return subgraph for the key attribute
* @throws IllegalArgumentException if the attribute is not an
*
attribute of this entity.
* @throws IllegalArgumentException if the attribute's target
*
type is not a managed type
* @throws IllegalStateException if this EntityGraph has been
*
statically defined
*/
public <X> Subgraph<X> addKeySubgraph(String attributeName);
/**
* Add a node to the graph that corresponds to a map key
* that is a managed type with inheritance. This allows for
* construction of multi-node entity graphs that include related
* managed types. Subclass subgraphs will include the specified
* attributes of superclass subgraphs
* @param attributeName name of the attribute
* @param type entity subclass
* @return subgraph for the attribute
* @throws IllegalArgumentException if the attribute is not an
*
attribute of this entity.
* @throws IllegalArgumentException if the attribute's target
*
type is not a managed type
* @throws IllegalStateException if this EntityGraph has been
*
statically defined
*/
public <X> Subgraph<X> addKeySubgraph(String attributeName,
Class<X> type);
4/2/13
116
JSR-338 Final Release
Oracle
Entity Graphs
Java Persistence 2.1, Final Release
Entity Operations
/**
* Return the attribute nodes corresponding to the attributes of
* this managed type that are included in the subgraph.
* @return list of attribute nodes included in the subgraph
* or empty list if none have been defined
*/
public List<AttributeNode<?>> getAttributeNodes();
}
/**
* Return the type for which this subgraph was defined.
* @return managed type referenced by the subgraph
*/
public Class<T> getClassType();
3.7.4 Use of Entity Graphs in find and query operations
An entity graph can be used with the find method or as a query hint to override or augment
FetchType semantics.
The standard properties javax.persistence.fetchgraph and javax.persistence.loadgraph are used to specify such graphs to queries and find operations.
The default fetch graph for an entity or embeddable is defined to consist of the transitive closure of all
of its attributes that are specified as FetchType.EAGER (or defaulted as such).
The persistence provider is permitted to fetch additional entity state beyond that specified by a fetch
graph or load graph. It is required, however, that the persistence provider fetch all state specified by the
fetch or load graph.
3.7.4.1 Fetch Graph Semantics
When the javax.persistence.fetchgraph property is used to specify an entity graph,
attributes that are specified by attribute nodes of the entity graph are treated as FetchType.EAGER
and attributes that are not specified are treated as FetchType.LAZY.
The following rules apply, depending on attribute type. The rules of this section are applied recursively.
A primary key or version attribute never needs to be specified in an attribute node of a fetch graph.
(This applies to composite primary keys as well, including embedded id primary keys.) When an entity
is fetched, its primary key and version attributes are always fetched. It is not incorrect, however, to
specify primary key attributes or version attributes.
Attributes other than primary key and version attributes are assumed not to be fetched unless the
attribute is specified. The following rules apply to the specification of attributes.
• If the attribute is an embedded attribute, and the attribute is specified in an attribute node, but a
subgraph is not specified for the attribute, the default fetch graph for the embeddable is
fetched. If a subgraph is specified for the attribute, the attributes of the embeddable are fetched
according to their specification in the corresponding subgraph.
JSR-338 Final Release
117
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Entity Graphs
• If the attribute is an element collection of basic type, and the attribute is specified in an
attribute node, the element collection together with its basic elements is fetched.
• If the attribute is an element collection of embeddables, and the attribute is specified in an
attribute node, but a subgraph is not specified for the attribute, the element collection together
with the default fetch graph of its embeddable elements is fetched. If a subgraph is specified
for the attribute, the attributes of the embeddable elements are fetched according to the corresponding subgraph specification.
• If the attribute is a one-to-one or many-to-one relationship, and the attribute is specified in an
attribute node, but a subgraph is not specified for the attribute, the default fetch graph of the
target entity is fetched. If a subgraph is specified for the attribute, the attributes of the target
entity are fetched according to the corresponding subgraph specification.
• If the attribute is a one-to-many or many-to-many relationship, and the attribute is specified in
an attribute node, but a subgraph is not specified, the collection is fetched and the default fetch
graphs of the referenced entities are fetched. If a subgraph is specified for the attribute, the
entities in the collection are fetched according to the corresponding subgraph specification.
• If the key of a map which has been specified in an attribute node is a basic type, it is fetched. If
the key of a map which has been specified in an attribute node is an embedded type, the default
fetch graph is fetched for the embeddable. Otherwise, if the key of the map is an entity, and a
map key subgraph is not specified for the attribute node, the map key is fetched according to its
default fetch graph. If a key subgraph is specified for the map key attribute, the map key
attribute is fetched according to the map key subgraph specification.
Examples:
@NamedEntityGraph
@Entity
public class Phonenumber{
@Id
protected String number;
}
protected PhoneTypeEnum type;
...
In the above example, only the number attribute would be eagerly fetched.
4/2/13
118
JSR-338 Final Release
Oracle
Entity Graphs
Java Persistence 2.1, Final Release
Entity Operations
@NamedEntityGraph(
attributeNodes={@NamedAttributeNode("projects")}
)
@Entity
public class Employee{
@Id
@GeneratedValue
protected long id;
@Basic
protected String name;
@Basic
protected String employeeNumber;
@OneToMany()
protected List<Dependents> dependents;
@OneToMany()
protected List<Project> projects;
}
@OneToMany()
protected List<PhoneNumber> phoneNumbers;
...
@Entity
@Inheritance
public class Project{
@Id
@GeneratedValue
protected long id;
String name;
}
@OneToOne(fetch=FetchType.EAGER)
protected Requirements doc;
...
@Entity
public class LargeProject extends Project{
}
JSR-338 Final Release
@OneToOne(fetch=FetchType.LAZY)
protected Employee approver;
...
119
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Entity Graphs
@Entity
public class Requirements{
@Id
protected long id;
@Lob
protected String description;
}
@OneToOne(fetch=FetchType.LAZY)
protected Approval approval
...
In the above example, the Employee entity's primary key will be fetched as well as the related
Project instances, whose default fetch graph (id, name, and doc attributes) will be fetched. The
related Requirements object will be fetched according to its default fetch graph.
If the approver attribute of LargeProject were FetchType.EAGER, and if any of the projects
were instances of LargeProject, their approver attributes would also be fetched. Since the type
of the approver attribute is Employee, the approver's default fetch graph (id, name, and
employeeNumber attributes) would also be fetched.
3.7.4.2 Load Graph Semantics
When the javax.persistence.loadgraph property is used to specify an entity graph, attributes
that are specified by attribute nodes of the entity graph are treated as FetchType.EAGER and
attributes that are not specified are treated according to their specified or default FetchType.
The following rules apply. The rules of this section are applied recursively.
• A primary key or version attribute never needs to be specified in an attribute node of a load
graph. (This applies to composite primary keys as well, including embedded id primary keys.)
When an entity is fetched, its primary key and version attributes are always fetched. It is not
incorrect, however, to specify primary key attributes or version attributes.
• If the attribute is an embedded attribute, and the attribute is specified in an attribute node, but a
subgraph is not specified for the attribute, the default fetch graph for the embeddable is
fetched. If a subgraph is specified for the attribute, attributes that are specified by the subgraph
are also fetched.
• If the attribute is an element collection of basic type, and the attribute is specified in an
attribute node, the element collection together with its basic elements is fetched.
• If the attribute is an element collection of embeddables, and the attribute is specified in an
attribute node, the element collection together with the default fetch graph of its embeddable
elements is fetched. If a subgraph is specified for the attribute, attributes that are specified by
the subgraph are also fetched.
4/2/13
120
JSR-338 Final Release
Oracle
Entity Graphs
Java Persistence 2.1, Final Release
Entity Operations
• If the attribute is a one-to-one or many-to-one relationship, and the attribute is specified in an
attribute node, the default fetch graph of the target entity is fetched. If a subgraph is specified
for the attribute, attributes that are specified by the subgraph are also fetched.
• If the attribute is a one-to-many or many-to-many relationship, and the attribute is specified in
an attribute node, the collection is fetched and the default fetch graphs of the referenced entities are fetched. If a subgraph is specified for the attribute, attributes that are specified by the
subgraph are also fetched.
• If the key of a map which has been specified in an attribute node is a basic type, it is fetched. If
the key of a map which has been specified in an attribute node is an embedded type, the default
fetch graph is fetched for the embeddable. Otherwise, if the key of the map is an entity, the
map key is fetched according to its default fetch graph. If a key subgraph is specified for the
map key attribute, additional attributes are fetched as specified in the key subgraph.
Examples:
@NamedEntityGraph
@Entity
public class Phonenumber{
@Id
protected String number;
}
protected PhoneTypeEnum type;
...
In the above example, the number and type attributes are fetched.
@NamedEntityGraph(
attributeNodes={@NamedAttributeNode("projects")}
)
@Entity
public class Employee{
@Id
@GeneratedValue
protected long id;
@Basic
protected String name;
@Basic
protected String employeeNumber;
@OneToMany()
protected List<Dependents> dependents;
@OneToMany()
protected List<Project> projects;
JSR-338 Final Release
121
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
}
Type Conversion of Basic Attributes
@OneToMany()
protected List<PhoneNumber> phoneNumbers;
...
@Entity
@Inheritance
public class Project{
@Id
@GeneratedValue
protected long id;
String name;
}
@OneToOne(fetch=FetchType.EAGER)
protected Requirements doc;
...
@Entity
public class LargeProject extends Project{
}
@OneToOne(fetch=FetchType.LAZY)
protected Employee approver;
...
@Entity
public class Requirements{
@Id
protected long id;
@Lob
protected String description;
}
@OneToOne(fetch=FetchType.LAZY)
protected Approval approval
...
In the above example, the default fetch graph (id, name, employeeNumber attributes) of
Employee is fetched. The default fetch graphs of the related Project instances (id, name, and
doc attributes) and their Requirements instances (id and description attributes) are also
fetched.
3.8 Type Conversion of Basic Attributes
The attribute conversion facility allows the developer to specify methods to convert between the entity
attribute representation and the database representation for attributes of basic types. Converters can be
used to convert basic attributes defined by entity classes, mapped superclasses, or embeddable
classes.[50]
4/2/13
122
JSR-338 Final Release
Oracle
Type Conversion of Basic Attributes
Java Persistence 2.1, Final Release
Entity Operations
An attribute converter must implement the javax.persistence.AttributeConverter interface. A converter implementation class must be annotated with the Converter annotation or defined
in the XML descriptor as a converter. If the value of the autoApply element of the Converter
annotation is true, the converter will be applied to all attributes of the target type, including to basic
attribute values that are contained within other, more complex attribute types. See Section 10.6.
/**
* A class that implements this interface can be used to convert
* entity attribute state into database column representation
* and back again.
* Note that the X and Y types may be the same Java type.
*
* @param X the type of the entity attribute
* @param Y the type of the database column
*/
public interface AttributeConverter<X,Y> {
/**
* Converts the value stored in the entity attribute into the
* data representation to be stored in the database.
*
* @param attribute the entity attribute value to be converted
* @return the converted data to be stored in the database
*
column
*/
public Y convertToDatabaseColumn (X attribute);
}
/**
* Converts the data stored in the database column into the
* value to be stored in the entity attribute.
* Note that it is the responsibility of the converter writer to
* specify the correct dbData type for the corresponding column
* for use by the JDBC driver: i.e., persistence providers are
* not expected to do such type conversion.
*
* @param dbData the data from the database column to be
*
converted
* @return the converted value to be stored in the entity
*
attribute
*/
public X convertToEntityAttribute (Y dbData);
The conversion of all basic types is supported except for the following: Id attributes (including the
attributes of embedded ids and derived identities), version attributes, relationship attributes, and
attributes explicitly annotated as Enumerated or Temporal or designated as such in the XML
descriptor. Auto-apply converters will not be applied to such attributes, and applications that apply converters to such attributes through use of the Convert annotation will not be portable.
Type conversion may be specified at the level of individual attributes by means of the Convert annotation. The Convert annotation may also be used to override or disable an auto-apply conversion.
See section 11.1.10.
[50] We plan to provide a facility for more complex attribute conversions in a future release of this specification.
JSR-338 Final Release
123
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Caching
The Convert annotation may be applied directly to an attribute of an entity, mapped superclass, or
embeddable class to specify conversion of the attribute or to override the use of a converter that has
been specified as autoApply=true. When persistent properties are used, the Convert annotation
is applied to the getter method.
The Convert annotation may be applied to an entity that extends a mapped superclass to specify or
override the conversion mapping for an inherited basic or embedded attribute.
The persistence provider runtime is responsible for invoking the specified conversion methods for the
target attribute type when loading the entity attribute from the database and before storing the entity
attribute state to the database. The persistence provider must apply any conversion methods to
instances of attribute values in path expressions used within Java Persistence query language queries or
criteria queries (such as in comparisons, bulk updates, etc.) before sending them to the database for the
query execution. When such converted attributes are used in comparison operations with literals or
parameters, the value of the literal or parameter to which they are compared must also be converted. If
the result of a Java Persistence query language query or criteria query includes one or more entity
attributes for which conversion mappings have been specified, the persistence provider must apply the
specified conversions to the corresponding values in the query result before returning them to the application. The use of functions, including aggregates, on converted attributes is undefined. If an exception
is thrown from a conversion method, the persistence provider must wrap the exception in a PersistenceException and, if the persistence context is joined to a transaction, mark the transaction for rollback.
3.9 Caching
This specification supports the use of a second-level cache by the persistence provider. The second-level cache, if used, underlies the persistence context, and is largely transparent to the application.
A second-level cache is typically used to enhance performance. Use of a cache, however, may have
consequences in terms of the up-to-dateness of the data seen by the application, resulting in “stale
reads”. A stale read is defined as the reading of entities or entity state that is older than the point at
which the persistence context was started.
This specification defines the following portable configuration options that can be used by the application developer to control caching behavior. Persistence providers may support additional provider-specific options, but must observe all specification-defined options.
3.9.1 The shared-cache-mode Element
Whether the entities and entity-related state of a persistence unit will be cached is determined by the
value of the shared-cache-mode element of the persistence.xml file.
The shared-cache-mode element has five possible values: ALL, NONE, ENABLE_SELECTIVE,
DISABLE_SELECTIVE, UNSPECIFIED.
A value of ALL causes all entities and entity-related state and data to be cached.
4/2/13
124
JSR-338 Final Release
Oracle
Caching
Java Persistence 2.1, Final Release
Entity Operations
A value of NONE causes caching to be disabled for the persistence unit. Persistence providers must not
cache if NONE is specified.
The values ENABLE_SELECTIVE and DISABLE_SELECTIVE are used in conjunction with the
Cacheable annotation (or XML element). The Cacheable annotation specifies whether an entity
should be cached if such selective caching is enabled by the persistence.xml
shared-cache-mode element. The Cacheable element is specified on the entity class. It applies
to the given entity and its subclasses unless subsequently overridden by a subclass.
• Cacheable(false) means that the entity and its state must not be cached by the provider.
• A value of ENABLE_SELECTIVE enables the cache and causes entities for which Cache-
able(true) (or its XML equivalent) is specified to be cached. Entities for which Cacheable(true) is not specified or for which Cacheable(false) is specified must not be
cached.
• A value of DISABLE_SELECTIVE enables the cache and causes all entities to be cached
except those for which Cacheable(false) is specified. Entities for which Cacheable(false) is specified must not be cached.
If either the shared-cache-mode element is not specified in the persistence.xml file or the
value of the shared-cache-mode element is UNSPECIFIED, and the javax.persistence.sharedCache.mode property is not specified, the behavior is not defined, and provider-specific defaults may apply.
If the shared-cache-mode element and the
javax.persistence.sharedCache.mode property are not specified, the semantics of the
Cacheable annotation (and XML equivalent) are undefined.
The persistence provider is not required to support use of a second-level cache. If the persistence provider does not support use of a second-level cache or a second-level cache is not installed, this element
will be ignored and no caching will occur.
Further control over the second-level cache is described in section 7.10.
3.9.2 Cache Retrieve Mode and Cache Store Mode Properties
Cache retrieve mode and cache store mode properties may be specified at the level of the persistence
context by means of the EntityManager setProperty method. These properties may be specified for
the EntityManager find and refresh methods and the Query, TypedQuery, and StoredProcedureQuery setHint methods. Cache retrieve mode and/or cache store mode properties
specified for the find, refresh, and Query, TypedQuery, and StoredProcedureQuery
setHint methods override those specified for the persistence context for the specified find and
refresh invocations, and for the execution of the specified queries respectively.
If caching is disabled by the NONE value of the shared-cache-mode element, cache retrieve mode
and cache store mode properties must be ignored. Otherwise, if the ENABLE_SELECTIVE value is
specified, but Cacheable(true) is not specified for a particular entity, they are ignored for that
entity; if the DISABLE_SELECTIVE value is specified, they are ignored for any entities for which
Cacheable(false) is specified.
JSR-338 Final Release
125
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Caching
Cache retrieve mode and cache store mode properties must be observed when caching is enabled,
regardless of whether caching is enabled due to the specification of the shared-cache-mode element or enabled due to provider-specific options. Applications that make use of cache retrieve mode or
cache store mode properties but which do not specify the shared-cache-mode element will not be
portable.
The cache retrieve mode and cache store mode properties are javax.persistence.cache.retrieveMode and javax.persistence.cache.storeMode respectively.
These properties have the semantics defined below.
The retrieveMode property specifies the behavior when data is retrieved by the find methods and
by the execution of queries. The retrieveMode property is ignored for the refresh method,
which always causes data to be retrieved from the database, not the cache.
package javax.persistence;
public enum CacheRetrieveMode {
/**
* Read entity data from the cache: this is
* the default behavior.
*/
USE,
}
/**
* Bypass the cache: get data directly from
* the database.
*/
BYPASS
The storeMode property specifies the behavior when data is read from the database and when data is
committed into the database.
package javax.persistence;
public enum CacheStoreMode {
/**
* Insert entity data into cache when read from database
* and insert/update entity data when committed into database:
* this is the default behavior. Does not force refresh of
* already cached items when reading from database.
*/
USE,
/**
* Don't insert into cache.
*/
BYPASS,
4/2/13
126
JSR-338 Final Release
Oracle
Caching
Java Persistence 2.1, Final Release
}
JSR-338 Final Release
Entity Operations
/**
* Insert/update entity data into cache when read
* from database and when committed into database.
* Forces refresh of cache for items read from database.
*/
REFRESH
127
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Query APIs
3.10 Query APIs
The Query and TypedQuery APIs are used for the execution of both static queries and dynamic queries. These APIs also support parameter binding and pagination control. The StoredProcedureQuery API is used for the execution of queries that invoke stored procedures defined in the database.
3.10.1 Query Interface
package javax.persistence;
import
import
import
import
import
java.util.Calendar;
java.util.Date;
java.util.List;
java.util.Set;
java.util.Map;
/**
* Interface used to control query execution.
*/
public interface Query {
/**
* Execute a SELECT query and return the query results
* as an untyped List.
* @return a list of the results
* @throws IllegalStateException if called for a Java
*
Persistence query language UPDATE or DELETE statement
* @throws QueryTimeoutException if the query execution exceeds
*
the query timeout value set and only the statement is
*
rolled back
* @throws TransactionRequiredException if a lock mode other
*
than NONE has been been set and there is no
*
transaction or the persistence context has not been
*
joined to the transaction
* @throws PessimisticLockException if pessimistic locking
*
fails and the transaction is rolled back
* @throws LockTimeoutException if pessimistic locking
*
fails and only the statement is rolled back
* @throws PersistenceException if the query execution exceeds
*
the query timeout value set and the transaction
*
is rolled back
*/
List getResultList();
/**
* Execute
* @return
* @throws
* @throws
* @throws
*
* @throws
*
*
* @throws
*
4/2/13
a SELECT query that returns a single untyped result.
the result
NoResultException if there is no result
NonUniqueResultException if more than one result
IllegalStateException if called for a Java
Persistence query language UPDATE or DELETE statement
QueryTimeoutException if the query execution exceeds
the query timeout value set and only the statement is
rolled back
TransactionRequiredException if a lock mode other
than NONE has been been set and there is no
128
JSR-338 Final Release
Oracle
Query APIs
Java Persistence 2.1, Final Release
Entity Operations
*
transaction or the persistence context has not been
*
joined to the transaction
* @throws PessimisticLockException if pessimistic locking
*
fails and the transaction is rolled back
* @throws LockTimeoutException if pessimistic locking
*
fails and only the statement is rolled back
* @throws PersistenceException if the query execution exceeds
*
the query timeout value set and the transaction
*
is rolled back
*/
Object getSingleResult();
/**
* Execute an update or delete statement.
* @return the number of entities updated or deleted
* @throws IllegalStateException if called for a Java
*
Persistence query language SELECT statement or for
*
a criteria query
* @throws TransactionRequiredException if there is
*
no transaction or the persistence context has not
*
been joined to the transaction
* @throws QueryTimeoutException if the statement execution
*
exceeds the query timeout value set and only the
*
statement is rolled back
* @throws PersistenceException if the query execution exceeds
*
the query timeout value set and the transaction
*
is rolled back
*/
int executeUpdate();
/**
* Set the maximum number of results to retrieve.
* @param maxResult
* @return the same query instance
* @throws IllegalArgumentException if the argument is negative
*/
Query setMaxResults(int maxResult);
/**
* The maximum number of results the query object was set to
* retrieve. Returns Integer.MAX_VALUE if setMaxResults was not
* applied to the query object.
* @return maximum number of results
*/
int getMaxResults();
/**
* Set the position of the first result to retrieve.
* @param startPosition position of the first result,
* numbered from 0
* @return the same query instance
* @throws IllegalArgumentException if the argument is negative
*/
Query setFirstResult(int startPosition);
JSR-338 Final Release
129
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Query APIs
/**
* The position of the first result the query object was set to
* retrieve. Returns 0 if setFirstResult was not applied to the
* query object.
* @return position of the first result
*/
int getFirstResult();
/**
* Set a query property or hint. The hints elements may be used
* to specify query properties and hints. Properties defined by
* this specification must be observed by the provider.
* Vendor-specific hints that are not recognized by a provider
* must be silently ignored. Portable applications should not
* rely on the standard timeout hint. Depending on the database
* in use and the locking mechanisms used by the provider,
* this hint may or may not be observed.
* @param hintName name of the property or hint
* @param value
* @return the same query instance
* @throws IllegalArgumentException if the second argument is not
*
valid for the implementation
*/
Query setHint(String hintName, Object value);
/**
* Get the properties and hints and associated values that are
* in effect for the query instance.
* @return query properties and hints
*/
Map<String, Object> getHints();
/**
* Bind the value of a Parameter object.
* @param param parameter object
* @param value parameter value
* @return the same query instance
* @throws IllegalArgumentException if the parameter
*
does not correspond to a parameter of the query
*/
<T> Query setParameter(Parameter<T> param, T value);
/**
* Bind an instance of java.util.Calendar to a Parameter object.
* @param param parameter object
* @param value parameter value
* @param temporalType
* @return the same query instance
* @throws IllegalArgumentException if the parameter does not
*
correspond to a parameter of the query
*/
Query setParameter(Parameter<Calendar> param,
Calendar value,
TemporalType temporalType);
4/2/13
130
JSR-338 Final Release
Oracle
Query APIs
Java Persistence 2.1, Final Release
Entity Operations
/**
* Bind an instance of java.util.Date to a Parameter object.
* @param param parameter object
* @param value parameter value
* @param temporalType
* @return the same query instance
* @throws IllegalArgumentException if the parameter does not
*
correspond to a parameter of the query
*/
Query setParameter(Parameter<Date> param,
Date value,
TemporalType temporalType);
/**
* Bind an argument value to a named parameter.
* @param name parameter name
* @param value parameter value
* @return the same query instance
* @throws IllegalArgumentException if the parameter name does
*
not correspond to a parameter of the query or if
*
the argument is of incorrect type
*/
Query setParameter(String name, Object value);
/**
* Bind an instance of java.util.Calendar to a named parameter.
* @param name parameter name
* @param value parameter value
* @param temporalType
* @return the same query instance
* @throws IllegalArgumentException if the parameter name does
*
not correspond to a parameter of the query or if
*
the value argument is of incorrect type
*/
Query setParameter(String name,
Calendar value,
TemporalType temporalType);
/**
* Bind an instance of java.util.Date to a named parameter.
* @param name parameter name
* @param value parameter value
* @param temporalType
* @return the same query instance
* @throws IllegalArgumentException if the parameter name does
*
not correspond to a parameter of the query or if
*
the value argument is of incorrect type
*/
Query setParameter(String name,
Date value,
TemporalType temporalType);
JSR-338 Final Release
131
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Query APIs
/**
* Bind an argument value to a positional parameter.
* @param position
* @param value parameter value
* @return the same query instance
* @throws IllegalArgumentException if position does not
*
correspond to a positional parameter of the
*
query or if the argument is of incorrect type
*/
Query setParameter(int position, Object value);
/**
* Bind an instance of java.util.Calendar to a positional
* parameter.
* @param position
* @param value parameter value
* @param temporalType
* @return the same query instance
* @throws IllegalArgumentException if position does not
*
correspond to a positional parameter of the query or
*
if the value argument is of incorrect type
*/
Query setParameter(int position,
Calendar value,
TemporalType temporalType);
/**
* Bind an instance of java.util.Date to a positional parameter.
* @param position
* @param value parameter value
* @param temporalType
* @return the same query instance
* @throws IllegalArgumentException if position does not
*
correspond to a positional parameter of the query or
*
if the value argument is of incorrect type
*/
Query setParameter(int position,
Date value,
TemporalType temporalType);
/**
* Get the parameter objects corresponding to the declared
* parameters of the query.
* Returns empty set if the query has no parameters.
* This method is not required to be supported for native
* queries.
* @return set of the parameter objects
* @throws IllegalStateException if invoked on a native
*
query when the implementation does not support
*
this use
*/
Set<Parameter<?>> getParameters();
/**
* Get the parameter object corresponding to the declared
* parameter of the given name.
* This method is not required to be supported for native
* queries.
* @param name
4/2/13
132
JSR-338 Final Release
Oracle
Query APIs
Java Persistence 2.1, Final Release
Entity Operations
* @return parameter object
* @throws IllegalArgumentException if the parameter of the
*
specified name does not exist
* @throws IllegalStateException if invoked on a native
*
query when the implementation does not support
*
this use
*/
Parameter<?> getParameter(String name);
/**
* Get the parameter object corresponding to the declared
* parameter of the given name and type.
* This method is required to be supported for criteria queries
* only.
* @param name parameter name
* @param type
* @return parameter object
* @throws IllegalArgumentException if the parameter of the
*
specified name does not exist or is not assignable
*
to the type
* @throws IllegalStateException if invoked on a native
*
query or Java Persistence query language query when
*
the implementation does not support this use
*/
<T> Parameter<T> getParameter(String name, Class<T> type);
/**
* Get the parameter object corresponding to the declared
* positional parameter with the given position.
* This method is not required to be supported for native
* queries.
* @param position
* @return parameter object
* @throws IllegalArgumentException if the parameter with the
*
specified position does not exist
* @throws IllegalStateException if invoked on a native
*
query when the implementation does not support
*
this use
*/
Parameter<?> getParameter(int position);
/**
* Get the parameter object corresponding to the declared
* positional parameter with the given position and type.
* This method is not required to be supported by the provider.
* @param position
* @param type
* @return parameter object
* @throws IllegalArgumentException if the parameter with the
*
specified position does not exist or is not assignable
*
to the type
* @throws IllegalStateException if invoked on a native
*
query or Java Persistence query language query when
*
the implementation does not support this use
*/
<T> Parameter<T> getParameter(int position, Class<T> type);
JSR-338 Final Release
133
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Query APIs
/**
* Return a boolean indicating whether a value has been bound
* to the parameter.
* @param param parameter object
* @return boolean indicating whether parameter has been bound
*/
boolean isBound(Parameter<?> param);
/**
* Return the input value bound to the parameter.
* (Note that OUT parameters are unbound.)
* @param param parameter object
* @return parameter value
* @throws IllegalArgumentException if the parameter is not
*
a parameter of the query
* @throws IllegalStateException if the parameter has not been
*
been bound
*/
<T> T getParameterValue(Parameter<T> param);
/**
* Return the input value bound to the named parameter.
* (Note that OUT parameters are unbound.)
* @param name parameter name
* @return parameter value
* @throws IllegalStateException if the parameter has not been
*
been bound
* @throws IllegalArgumentException if the parameter of the
*
specified name does not exist
*/
Object getParameterValue(String name);
/**
* Return the input value bound to the positional parameter.
* (Note that OUT parameters are unbound.)
* @param position
* @return parameter value
* @throws IllegalStateException if the parameter has not been
*
been bound
* @throws IllegalArgumentException if the parameter with the
*
specified position does not exist
*/
Object getParameterValue(int position);
/**
* Set the flush mode type to be used for the query execution.
* The flush mode type applies to the query regardless of the
* flush mode type in use for the entity manager.
* @param flushMode
* @return the same query instance
*/
Query setFlushMode(FlushModeType flushMode);
4/2/13
134
JSR-338 Final Release
Oracle
Query APIs
Java Persistence 2.1, Final Release
Entity Operations
/**
* Get the flush mode in effect for the query execution.
* If a flush mode has not been set for the query object,
* returns the flush mode in effect for the entity manager.
* @return flush mode
*/
FlushModeType getFlushMode();
/**
* Set the lock mode type to be used for the query execution.
* @param lockMode
* @return the same query instance
* @throws IllegalStateException if the query is found not to be
*
a Java Persistence query language SELECT query
*
or a CriteriaQuery query
*/
Query setLockMode(LockModeType lockMode);
/**
* Get the current lock mode for the query. Returns null if a
* lock mode has not been set on the query object.
* @return lock mode
* @throws IllegalStateException if the query is found not to be
*
a Java Persistence query language SELECT query or
*
a Criteria API query
*/
LockModeType getLockMode();
}
JSR-338 Final Release
/**
* Return an object of the specified type to allow access to
* the provider-specific API. If the provider's query
* implementation does not support the specified class, the
* PersistenceException is thrown.
* @param cls the class of the object to be returned. This is
*
normally either the underlying query
*
implementation class or an interface that it
*
implements.
* @return an instance of the specified class
* @throws PersistenceException if the provider does not support
*
the call
*/
<T> T unwrap(Class<T> cls);
135
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Query APIs
3.10.2 TypedQuery Interface
package javax.persistence;
import java.util.List;
import java.util.Date;
import java.util.Calendar;
/**
* Interface used to control the execution of typed queries.
* @param <X> query result type
*/
public interface TypedQuery<X> extends Query {
/**
* Execute a SELECT query and return the query results
* as a typed List.
* @return a list of the results
* @throws IllegalStateException if called for a Java
*
Persistence query language UPDATE or DELETE statement
* @throws QueryTimeoutException if the query execution exceeds
*
the query timeout value set and only the statement is
*
rolled back
* @throws TransactionRequiredException if a lock mode other
*
than NONE has been been set and there is no
*
transaction or the persistence context has not been
*
joined to the transaction
* @throws PessimisticLockException if pessimistic locking
*
fails and the transaction is rolled back
* @throws LockTimeoutException if pessimistic locking
*
fails and only the statement is rolled back
* @throws PersistenceException if the query execution exceeds
*
the query timeout value set and the transaction
*
is rolled back
*/
List<X> getResultList();
/**
* Execute a SELECT query that returns a single result.
* @return the result
* @throws NoResultException if there is no result
* @throws NonUniqueResultException if more than one result
* @throws IllegalStateException if called for a Java
*
Persistence query language UPDATE or DELETE statement
* @throws QueryTimeoutException if the query execution exceeds
*
the query timeout value set and only the statement is
*
rolled back
* @throws TransactionRequiredException if a lock mode other
*
than NONE has been been set and there is no
*
transaction or the persistence context has not been
*
joined to the transaction
* @throws PessimisticLockException if pessimistic locking
*
fails and the transaction is rolled back
* @throws LockTimeoutException if pessimistic locking
*
fails and only the statement is rolled back
* @throws PersistenceException if the query execution exceeds
*
the query timeout value set and the transaction
*
is rolled back
*/
X getSingleResult();
4/2/13
136
JSR-338 Final Release
Oracle
Query APIs
Java Persistence 2.1, Final Release
Entity Operations
/**
* Set the maximum number of results to retrieve.
* @param maxResult
* @return the same query instance
* @throws IllegalArgumentException if the argument is negative
*/
TypedQuery<X> setMaxResults(int maxResult);
/**
* Set the position of the first result to retrieve.
* @param startPosition position of the first result,
*
numbered from 0
* @return the same query instance
* @throws IllegalArgumentException if the argument is negative
*/
TypedQuery<X> setFirstResult(int startPosition);
/**
* Set a query property or hint. The hints elements may be used
* to specify query properties and hints. Properties defined by
* this specification must be observed by the provider.
* Vendor-specific hints that are not recognized by a provider
* must be silently ignored. Portable applications should not
* rely on the standard timeout hint. Depending on the database
* in use and the locking mechanisms used by the provider,
* this hint may or may not be observed.
* @param hintName name of property or hint
* @param value
* @return the same query instance
* @throws IllegalArgumentException if the second argument is not
*
valid for the implementation
*/
TypedQuery<X> setHint(String hintName, Object value);
/**
* Bind the value of a Parameter object.
* @param param parameter object
* @param value parameter value
* @return the same query instance
* @throws IllegalArgumentException if the parameter
*
does not correspond to a parameter of the
*
query
*/
<T> TypedQuery<X> setParameter(Parameter<T> param, T value);
/**
* Bind an instance of java.util.Calendar to a Parameter object.
* @param param parameter object
* @param value parameter value
* @param temporalType
* @return the same query instance
* @throws IllegalArgumentException if the parameter does not
*
correspond to a parameter of the query
*/
TypedQuery<X> setParameter(Parameter<Calendar> param,
Calendar value,
TemporalType temporalType);
JSR-338 Final Release
137
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Query APIs
/**
* Bind an instance of java.util.Date to a Parameter object.
* @param param parameter object
* @param value parameter value
* @param temporalType
* @return the same query instance
* @throws IllegalArgumentException if the parameter does not
*
correspond to a parameter of the query
*/
TypedQuery<X> setParameter(Parameter<Date> param,
Date value,
TemporalType temporalType);
/**
* Bind an argument value to a named parameter.
* @param name parameter name
* @param value parameter value
* @return the same query instance
* @throws IllegalArgumentException if the parameter name does
*
not correspond to a parameter of the query or if
*
the argument is of incorrect type
*/
TypedQuery<X> setParameter(String name, Object value);
/**
* Bind an instance of java.util.Calendar to a named parameter.
* @param name parameter name
* @param value parameter value
* @param temporalType
* @return the same query instance
* @throws IllegalArgumentException if the parameter name does
*
not correspond to a parameter of the query or if
*
the value argument is of incorrect type
*/
TypedQuery<X> setParameter(String name,
Calendar value,
TemporalType temporalType);
/**
* Bind an instance of java.util.Date to a named parameter.
* @param name parameter name
* @param value parameter value
* @param temporalType
* @return the same query instance
* @throws IllegalArgumentException if the parameter name does
*
not correspond to a parameter of the query or if
*
the value argument is of incorrect type
*/
TypedQuery<X> setParameter(String name,
Date value,
TemporalType temporalType);
4/2/13
138
JSR-338 Final Release
Oracle
Query APIs
Java Persistence 2.1, Final Release
Entity Operations
/**
* Bind an argument value to a positional parameter.
* @param position
* @param value parameter value
* @return the same query instance
* @throws IllegalArgumentException if position does not
*
correspond to a positional parameter of the
*
query or if the argument is of incorrect type
*/
TypedQuery<X> setParameter(int position, Object value);
/**
* Bind an instance of java.util.Calendar to a positional
* parameter.
* @param position
* @param value parameter value
* @param temporalType
* @return the same query instance
* @throws IllegalArgumentException if position does not
*
correspond to a positional parameter of the query
*
or if the value argument is of incorrect type
*/
TypedQuery<X> setParameter(int position,
Calendar value,
TemporalType temporalType);
/**
* Bind an instance of java.util.Date to a positional parameter.
* @param position
* @param value parameter value
* @param temporalType
* @return the same query instance
* @throws IllegalArgumentException if position does not
*
correspond to a positional parameter of the query
*
or if the value argument is of incorrect type
*/
TypedQuery<X> setParameter(int position,
Date value,
TemporalType temporalType);
/**
* Set the flush mode type to be used for the query execution.
* The flush mode type applies to the query regardless of the
* flush mode type in use for the entity manager.
* @param flushMode
* @return the same query instance
*/
TypedQuery<X> setFlushMode(FlushModeType flushMode);
}
JSR-338 Final Release
/**
* Set the lock mode type to be used for the query execution.
* @param lockMode
* @return the same query instance
* @throws IllegalStateException if the query is found not to
*
be a Java Persistence query language SELECT query
*
or a CriteriaQuery query
*/
TypedQuery<X> setLockMode(LockModeType lockMode);
139
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Query APIs
3.10.3 Tuple Interface
package javax.persistence;
import java.util.List;
/**
* Interface for extracting the elements of a query result tuple.
*/
public interface Tuple {
/**
* Get the value of the specified tuple element.
* @param tupleElement tuple element
* @return value of tuple element
* @throws IllegalArgumentException if tuple element
*
does not correspond to an element in the
*
query result tuple
*/
<X> X get(TupleElement<X> tupleElement);
/**
* Get the value of the tuple element to which the
* specified alias has been assigned.
* @param alias alias assigned to tuple element
* @param type of the tuple element
* @return value of the tuple element
* @throws IllegalArgumentException if alias
*
does not correspond to an element in the
*
query result tuple or element cannot be
*
assigned to the specified type
*/
<X> X get(String alias, Class<X> type);
/**
* Get the value of the tuple element to which the
* specified alias has been assigned.
* @param alias alias assigned to tuple element
* @return value of the tuple element
* @throws IllegalArgumentException if alias
*
does not correspond to an element in the
*
query result tuple
*/
Object get(String alias);
/**
* Get the value of the element at the specified
* position in the result tuple. The first position is 0.
* @param i position in result tuple
* @param type type of the tuple element
* @return value of the tuple element
* @throws IllegalArgumentException if i exceeds
*
length of result tuple or element cannot be
*
assigned to the specified type
*/
<X> X get(int i, Class<X> type);
4/2/13
140
JSR-338 Final Release
Oracle
Query APIs
Java Persistence 2.1, Final Release
Entity Operations
/**
* Get the value of the element at the specified
* position in the result tuple. The first position is 0.
* @param i position in result tuple
* @return value of the tuple element
* @throws IllegalArgumentException if i exceeds
*
length of result tuple
*/
Object get(int i);
/**
* Return the values of the result tuple elements as an array.
* @return tuple element values
*/
Object[] toArray();
}
/**
* Return the tuple elements.
* @return tuple elements
*/
List<TupleElement<?>> getElements();
3.10.4 TupleElement Interface
package javax.persistence;
/**
* The TupleElement interface defines an element that is returned in
* a query result tuple.
* @param <X> the type of the element
*/
public interface TupleElement<X> {
/**
* Return the runtime Java type of the tuple element.
* @return the runtime Java type of the tuple element
*/
Class<? extends X> getJavaType();
}
JSR-338 Final Release
/**
* Return the alias assigned to the tuple element or null,
* if no alias has been assigned.
* @return alias
*/
String getAlias();
141
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Query APIs
3.10.5 Parameter Interface
package javax.persistence;
/**
* Type for query parameter objects.
* @param <T> the type of the parameter
*/
public interface Parameter<T> {
/**
* Return the parameter name, or null if the parameter is
* not a named parameter or no name has been assigned.
* @return parameter name
*/
String getName();
/**
* Return the parameter position, or null if the parameter is
* not a positional parameter.
* @return position of parameter
*/
Integer getPosition();
}
4/2/13
/**
* Return the Java type of the parameter. Values bound to the
* parameter must be assignable to this type.
* This method is required to be supported for criteria queries
* only.
Applications that use this method for Java
* Persistence query language queries and native queries will
* not be portable.
* @return the Java type of the parameter
* @throws IllegalStateException if invoked on a parameter
*
obtained from a Java persistence query language
*
query or native query when the implementation does
*
not support this use
*/
Class<T> getParameterType();
142
JSR-338 Final Release
Oracle
Query APIs
Java Persistence 2.1, Final Release
Entity Operations
3.10.6 StoredProcedureQuery Interface
package javax.persistence;
import java.util.Calendar;
import java.util.Date;
import java.util.List;
/**
* Interface used to control stored procedure query execution.*
*/
public interface StoredProcedureQuery extends Query {
/**
* Set a query property or hint. The hints elements may be used
* to specify query properties and hints. Properties defined by
* this specification must be observed by the provider.
* Vendor-specific hints that are not recognized by a provider
* must be silently ignored. Portable applications should not
* rely on the standard timeout hint. Depending on the database
* in use, this hint may or may not be observed.
* @param hintName name of the property or hint
* @param value value for the property or hint
* @return the same query instance
* @throws IllegalArgumentException if the second argument is not
*
valid for the implementation
*/
StoredProcedureQuery setHint(String hintName, Object value);
/**
* Bind the value of a Parameter object.
* @param param parameter object
* @param value parameter value
* @return the same query instance
* @throws IllegalArgumentException if the parameter does not
*
correspond to a parameter of the query
*/
<T> StoredProcedureQuery setParameter(Parameter<T> param,
T value);
/**
* Bind an instance of java.util.Calendar to a Parameter object.
* @param param parameter object
* @param value parameter value
* @param temporalType temporal type
* @return the same query instance
* @throws IllegalArgumentException if the parameter does not
*
correspond to a parameter of the query
*/
StoredProcedureQuery setParameter(Parameter<Calendar> param,
Calendar value,
TemporalType temporalType);
JSR-338 Final Release
143
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Query APIs
/**
* Bind an instance of java.util.Date to a Parameter object.
* @param param parameter object
* @param value parameter value
* @param temporalType temporal type
* @return the same query instance
* @throws IllegalArgumentException if the parameter does not
*
correspond to a parameter of the query
*/
StoredProcedureQuery setParameter(Parameter<Date> param,
Date value,
TemporalType temporalType);
/**
* Bind an argument to a named parameter.
* @param name parameter name
* @param value parameter value
* @return the same query instance
* @throws IllegalArgumentException if the parameter name does
*
not correspond to a parameter of the query or if the
*
argument is of incorrect type
*/
StoredProcedureQuery setParameter(String name, Object value);
/**
* Bind an instance of java.util.Calendar to a named parameter.
* @param name parameter name
* @param value parameter value
* @param temporalType temporal type
* @return the same query instance
* @throws IllegalArgumentException if the parameter name does
*
not correspond to a parameter of the query or if the
*
value argument is of incorrect type
*/
StoredProcedureQuery setParameter(String name,
Calendar value,
TemporalType temporalType);
/**
* Bind an instance of java.util.Date to a named parameter.
* @param name parameter name
* @param value parameter value
* @param temporalType temporal type
* @return the same query instance
* @throws IllegalArgumentException if the parameter name does
*
not correspond to a parameter of the query or if the
*
value argument is of incorrect type
*/
StoredProcedureQuery setParameter(String name,
Date value,
TemporalType temporalType);
4/2/13
144
JSR-338 Final Release
Oracle
Query APIs
Java Persistence 2.1, Final Release
Entity Operations
/**
* Bind an argument to a positional parameter.
* @param position position
* @param value parameter value
* @return the same query instance
* @throws IllegalArgumentException if position does not
*
correspond to a positional parameter of the query
*
or if the argument is of incorrect type
*/
StoredProcedureQuery setParameter(int position, Object value);
/**
* Bind an instance of java.util.Calendar to a positional
* parameter.
* @param position position
* @param value parameter value
* @param temporalType temporal type
* @return the same query instance
* @throws IllegalArgumentException if position does not
*
correspond to a positional parameter of the query or
*
if the value argument is of incorrect type
*/
StoredProcedureQuery setParameter(int position,
Calendar value,
TemporalType temporalType);
/**
* Bind an instance of java.util.Date to a positional parameter.
* @param position position
* @param value parameter value
* @param temporalType temporal type
* @return the same query instance
* @throws IllegalArgumentException if position does not
*
correspond to a positional parameter of the query or
*
if the value argument is of incorrect type
*/
StoredProcedureQuery setParameter(int position,
Date value,
TemporalType temporalType);
/**
* Set the flush mode type to be used for the query execution.
* The flush mode type applies to the query regardless of the
* flush mode type in use for the entity manager.
* @param flushMode flush mode
* @return the same query instance
*/
StoredProcedureQuery setFlushMode(FlushModeType flushMode);
JSR-338 Final Release
145
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Query APIs
/**
* Register a positional parameter.
* All positional parameters must be registered.
* @param position parameter position
* @param type type of the parameter
* @param mode parameter mode
* @return the same query instance
*/
StoredProcedureQuery registerStoredProcedureParameter(
int position,
Class type,
ParameterMode mode);
/**
* Register a named parameter.
* @param parameterName name of the parameter as registered or
*
specified in metadata
* @param type type of the parameter
* @param mode parameter mode
* @return the same query instance
*/
StoredProcedureQuery registerStoredProcedureParameter(
String parameterName,
Class type,
ParameterMode mode);
/**
* Retrieve a value passed back from the procedure through an
* INOUT or OUT parameter.
* For portability, all results corresponding to result sets
* and update counts must be retrieved before the values of
* output parameters.
* @param position parameter position
* @return the result that is passed back through the parameter
* @throws IllegalArgumentException if the position does
*
not correspond to a parameter of the query or is
*
not an INOUT or OUT parameter
*/
Object getOutputParameterValue(int position);
/**
* Retrieve a value passed back from the procedure through an
* INOUT or OUT parameter.
* For portability, all results corresponding to result sets
* and update counts must be retrieved before the values of
* output parameters.
* @param parameterName name of the parameter as registered or
*
specified in metadata
* @return the result that is passed back through the parameter
* @throws IllegalArgumentException if the parameter name does
*
not correspond to a parameter of the query or is
*
not an INOUT or OUT parameter
*/
Object getOutputParameterValue(String parameterName);
4/2/13
146
JSR-338 Final Release
Oracle
Query APIs
Java Persistence 2.1, Final Release
Entity Operations
/**
* Return true if the first result corresponds to a result set,
* and false if it is an update count or if there are no results
* other than through INOUT and OUT parameters, if any.
* @return true if first result corresponds to result set
* @throws QueryTimeoutException if the query execution exceeds
*
the query timeout value set and only the statement is
*
rolled back
* @throws PersistenceException if the query execution exceeds
*
the query timeout value set and the transaction
*
is rolled back
*/
boolean execute();
/**
* Return the update count of -1 if there is no pending result or
* if the first result is not an update count. The provider
* will call execute on the query if needed.
* @return the update count or -1 if there is no pending result
* or if the next result is not an update count.
* @throws TransactionRequiredException if there is
*
no transaction or the persistence context has not
*
been joined to the transaction
* @throws QueryTimeoutException if the statement execution
*
exceeds the query timeout value set and only
*
the statement is rolled back
* @throws PersistenceException if the query execution exceeds
*
the query timeout value set and the transaction
*
is rolled back
*/
int executeUpdate();
/**
* Retrieve the list of results from the next result set.
* The provider will call execute on the query if needed.
* A REF_CURSOR result set, if any, will be retrieved in the
* order the REF_CURSOR parameter was registered with the query.
* @return a list of the results or null is the next item is not
* a result set
* @throws QueryTimeoutException if the query execution exceeds
*
the query timeout value set and only the statement is
*
rolled back
* @throws PersistenceException if the query execution exceeds
*
the query timeout value set and the transaction
*
is rolled back
*/
List getResultList();
JSR-338 Final Release
147
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Query APIs
/**
* Retrieve a single result from the next result set.
* The provider will call execute on the query if needed.
* A REF_CURSOR result set, if any, will be retrieved in the
* order the REF_CURSOR parameter was registered with the query.
* @return the result or null if the next item is not a result set
* @throws NoResultException if there is no result in the next
*
result set
* @throws NonUniqueResultException if more than one result
* @throws QueryTimeoutException if the query execution exceeds
*
the query timeout value set and only the statement is
*
rolled back
* @throws PersistenceException if the query execution exceeds
*
the query timeout value set and the transaction
*
is rolled back
*/
Object getSingleResult();
/**
* Return true if the next result corresponds to a result set,
* and false if it is an update count or if there are no results
* other than through INOUT and OUT parameters, if any.
* @return true if next result corresponds to result set
* @throws QueryTimeoutException if the query execution exceeds
*
the query timeout value set and only the statement is
*
rolled back
* @throws PersistenceException if the query execution exceeds
*
the query timeout value set and the transaction
*
is rolled back
*/
boolean hasMoreResults();
}
/**
* Return the update count or -1 if there is no pending result
* or if the next result is not an update count.
* @return update count or -1 if there is no pending result or
*
if the next result is not an update count
* @throws QueryTimeoutException if the query execution exceeds
*
the query timeout value set and only the statement is
*
rolled back
* @throws PersistenceException if the query execution exceeds
*
the query timeout value set and the transaction
*
is rolled back
*/
int getUpdateCount();
3.10.7 Query Execution
Java Persistence query language, Criteria API, and native SQL select queries are executed using the
getResultList and getSingleResult methods. Update and delete operations (update and
delete “queries”) are executed using the executeUpdate method.
• For TypedQuery instances, the query result type is determined in the case of criteria queries
by the type of the query specified when the CriteriaQuery object is created, as described
in section 6.5.1, “CriteriaQuery Creation”. In the case of Java Persistence query language que-
4/2/13
148
JSR-338 Final Release
Oracle
Query APIs
Java Persistence 2.1, Final Release
Entity Operations
ries, the type of the result is determined by the resultClass argument to the createQuery or createNamedQuery method, and the select list of the query must contain only a
single item which must be assignable to the specified type.
• For Query instances, the elements of a query result whose select list consists of more than one
select expression are of type Object[]. If the select list consists of only one select expression, the elements of the query result are of type Object. When native SQL queries are used,
the SQL result set mapping (see section 3.10.16), determines how many items (entities, scalar
values, etc.) are returned. If multiple items are returned, the elements of the query result are of
type Object[]. If only a single item is returned as a result of the SQL result set mapping or
if a result class is specified, the elements of the query result are of type Object.
Stored procedure queries can be executed using the getResultList, getSingleResult, and
execute methods. Stored procedures that perform only updates or deletes can be executed using the
executeUpdate method. Stored procedure query execution is described in detail in section
3.10.17.3.
An IllegalArgumentException is thrown if a parameter instance is specified that does not correspond to a parameter of the query, if a parameter name is specified that does not correspond to a
named parameter of the query, if a positional value is specified that does not correspond to a positional
parameter of the query, or if the type of the parameter is not valid for the query. This exception may be
thrown when the parameter is bound, or the execution of the query may fail. See sections 3.10.11,
3.10.12, and 3.10.13 for supported parameter usage.
The effect of applying setMaxResults or setFirstResult to a query involving fetch joins over
collections is undefined. The use of setMaxResults and setFirstResult is not supported for
stored procedure queries.
Query and TypedQuery methods other than the executeUpdate method are not required to be
invoked within a transaction context, unless a lock mode other than LockModeType.NONE has been
specified for the query. In particular, the getResultList and getSingleResult methods are not
required to be invoked within a transaction context unless such a lock mode has been specified for the
query.[51] If an entity manager with transaction-scoped persistence context is in use, the resulting entities will be detached; if an entity manager with an extended persistence context is used, they will be
managed. See Chapter 7 for further discussion of entity manager use outside a transaction and persistence context types.
Whether a StoredProcedureQuery should be invoked in a transaction context should be determined by the transactional semantics and/or requirements of the stored procedure implementation and
the database in use. In particular, problems may occur if the stored procedure initiates a transaction and
a transaction is already in effect. The state of any entities returned by the stored procedure query invocation is determined as decribed above.
[51] A lock mode is specified for a query by means of the setLockMode method or by specifying the lock mode in the NamedQuery annotation.
JSR-338 Final Release
149
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Query APIs
Runtime exceptions other than the NoResultException, NonUniqueResultException,
QueryTimeoutException, and LockTimeoutException thrown by the methods of the
Query, TypedQuery, and StoredProcedureQuery interfaces other than those methods specified below cause the current transaction to be marked for rollback if the persistence context is joined to
the transaction. On database platforms on which a query timeout causes transaction rollback, the persistence provider must throw the PersistenceException instead of the QueryTimeoutException.
Runtime exceptions thrown by the following methods of the Query, TypedQuery, and StoredProcedureQuery interfaces do not cause the current transaction to be marked for rollback: getParameters, getParameter, getParameterValue, getOutputParameterValue,
getLockMode.
Runtime exceptions thrown by the methods of the Tuple, TupleElement, and Parameter interfaces do not cause the current transaction to be marked for rollback.
3.10.7.1 Example
public List findWithName(String name) {
return em.createQuery(
"SELECT c FROM Customer c WHERE c.name LIKE :custName")
.setParameter("custName", name)
.setMaxResults(10)
.getResultList();
}
3.10.8 Queries and Flush Mode
The flush mode setting affects the result of a query as follows.
When queries are executed within a transaction, if FlushModeType.AUTO is set on the Query,
TypedQuery, or StoredProcedureQuery object, or if the flush mode setting for the persistence
context is AUTO (the default) and a flush mode setting has not been specified for the query object, the
persistence provider is responsible for ensuring that all updates to the state of all entities in the persistence context which could potentially affect the result of the query are visible to the processing of the
query. The persistence provider implementation may achieve this by flushing those entities to the database or by some other means. If FlushModeType.COMMIT is set, the effect of updates made to entities in the persistence context upon queries is unspecified.
If the persistence context has not been joined to the current transaction, the persistence provider must
not flush to the database regardless of the flush mode setting.
package javax.persistence;
public enum FlushModeType {
COMMIT,
AUTO
}
If there is no transaction active, the persistence provider must not flush to the database.
4/2/13
150
JSR-338 Final Release
Oracle
Query APIs
Java Persistence 2.1, Final Release
Entity Operations
3.10.9 Queries and Lock Mode
The setLockMode method of the Query or TypedQuery interface or the lockMode element of
the NamedQuery annotation may be used to lock the results of a query. A lock is obtained for each
entity specified in the query result (including entities passed to constructors in the query SELECT
clause).[52]
If
the
lock
mode
type
is
PESSIMISTIC_READ,
PESSIMISTIC_WRITE,
or
PESSIMISTIC_FORCE_INCREMENT, and the query returns scalar data (e.g., the values of entity
field or properties, including scalar data passed to constructors in the query SELECT clause), the underlying database rows will be locked[53], but the version columns (if any) for any entities corresponding to
such scalar data will not be updated unless the entities themselves are also otherwise retrieved and
updated.
If the lock mode type is OPTIMISTIC or OPTIMISTIC_FORCE_INCREMENT, and the query returns
scalar data, any entities returned by the query will be locked, but no locking will occur for scalar data
that does not correspond to the state of any entity instance in the query result.
If a lock mode other than NONE is specified for a query, the query must be executed within a transaction
(and the persistence context must be joined to the transaction) or the TransactionRequiredException will be thrown.
Locking is supported for Java Persistence query language queries and criteria queries only. If the setLockMode or getLockMode method is invoked on a query that is not a Java Persistence query language select query or a criteria query, the IllegalStateException may be thrown or the query
execution will fail.
3.10.10 Query Hints
The following hint is defined by this specification for use in query configuration.
javax.persistence.query.timeout // time in milliseconds
This hint may be used with the Query, TypedQuery, or StoredProcedureQuery setHint
method or the NamedQuery, NamedNativeQuery, and NamedStoredProcedureQuery
annotations. It may also be passed as a property to the Persistence.createEntityManagerFactory method and used in the properties element of the persistence.xml file. See sections 3.10.1, 8.2.1.9, 9.7, 10.4. When used in the createEntityManagerFactory method, the
persistence.xml file, and annotations, the timeout hint serves as a default value which can be
selectively overridden by use in the setHint method.
Portable applications should not rely on this hint. Depending on the persistence provider and database in
use, the hint may or may not be observed.
[52] Note that the setLockMode method may be called more than once (with different values) on a Query or TypedQuery object.
[53] Note that locking will not occur for data passed to aggregate functions. Further, queries involving aggregates with pessimistic
locking may not be supported on all database platforms.
JSR-338 Final Release
151
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Query APIs
Vendors are permitted to support the use of additional, vendor-specific hints. Vendor-specific hints
must not use the javax.persistence namespace. Vendor-specific hints must be ignored if they are
not understood.
3.10.11 Parameter Objects
Parameter objects can be used for criteria queries and for Java Persistence query language queries.
Implementations may support the use of Parameter objects for native queries, however support for
Parameter objects with native queries is not required by this specification. The use of Parameter
objects for native queries will not be portable. The mixing of parameter objects with named or positional parameters is undefined.
Portable applications should not attempt to reuse a Parameter object obtained from a Query or
TypedQuery instance in the context of a different Query or TypedQuery instance.
3.10.12 Named Parameters
Named parameters can be used for Java Persistence query language queries, for criteria queries
(although use of Parameter objects is to be preferred), and for stored procedure queries that support
named parameters.
Named parameters follow the rules for identifiers defined in Section 4.4.1. Named parameters are
case-sensitive. The mixing of named and positional parameters is undefined.
A named parameter of a Java Persistence query language query is an identifier that is prefixed by the
":" symbol. The parameter names passed to the setParameter methods of the Query and
TypedQuery interfaces do not include this ":" prefix.
3.10.13 Positional Parameters
Only positional parameter binding and positional access to result items may be portably used for native
queries, except for stored procedure queries for which named parameters have been defined. When
binding the values of positional parameters, the numbering starts as “1”. It is assumed that for native
queries the parameters themselves use the SQL syntax (i.e., “?”, rather than “?1”).
The use of positional parameters is not supported for criteria queries.
3.10.14 Named Queries
Named queries are static queries expressed in metadata or queries registered by means of the EntityManagerFactory addNamedQuery method. Named queries can be defined in the Java Persistence
query language or in SQL. Query names are scoped to the persistence unit.
4/2/13
152
JSR-338 Final Release
Oracle
Query APIs
Java Persistence 2.1, Final Release
Entity Operations
The following is an example of the definition of a named query defined in metadata:
@NamedQuery(
name="findAllCustomersWithName",
query="SELECT c FROM Customer c WHERE c.name LIKE :custName"
)
The following is an example of the use of a named query:
@PersistenceContext
public EntityManager em;
...
customers = em.createNamedQuery("findAllCustomersWithName")
.setParameter("custName", "Smith")
.getResultList();
3.10.15 Polymorphic Queries
By default, all queries are polymorphic. That is, the FROM clause of a query designates not only
instances of the specific entity class(es) to which it explicitly refers, but subclasses as well. The
instances returned by a query include instances of the subclasses that satisfy the query conditions.
For example, the following query returns the average salary of all employees, including subtypes of
Employee, such as Manager and Exempt.
select avg(e.salary) from Employee e where e.salary > 80000
Entity type expressions, described in section 4.6.17.5, as well as the use of downcasting, described in
section 4.4.9, can be used to restrict query polymorphism.
3.10.16 SQL Queries
Queries may be expressed in native SQL. The result of a native SQL query may consist of entities,
unmanaged instances created via constructors, scalar values, or some combination of these.
The SQL query facility is intended to provide support for those cases where it is necessary to
use the native SQL of the target database in use (and/or where the Java Persistence query language cannot be used). Native SQL queries are not expected to be portable across databases.
3.10.16.1 Returning Managed Entities from Native Queries
The persistence provider is responsible for performing the mapping between the values returned by the
SQL query and entity attributes in accordance with the object/relational mapping metadata for the entity
or entities. In particular, the names of the columns in the SQL result are used to map to the entity
attributes as defined by this metadata. This mapping includes the mapping of the attributes of any
embeddable classes that are part of the non-collection-valued entity state and attributes corresponding to
foreign keys contained as part of the entity state[54].
[54] Support for joins is currently limited to single-valued relationships that are mapped directly—i.e., not via join tables.
JSR-338 Final Release
153
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Query APIs
When an entity is to be returned from a native query, the SQL statement should select all of the columns
that are mapped to the entity object. This should include foreign key columns to related entities. The
results obtained when insufficient data is available are undefined.
In the simplest case—i.e., when the results of the query are limited to entities of a single entity class and
the mapping information can be derived from the columns of the SQL result and the object/relational
mapping metadata—it is sufficient to specify only the expected class of the entity result.
The following example illustrates the case where a native SQL query is created dynamically using the
createNativeQuery method and the entity class that specifies the type of the result is passed in as
an argument.
Query q = em.createNativeQuery(
"SELECT o.id, o.quantity, o.item " +
"FROM Order o, Item i " +
"WHERE (o.item = i.id) AND (i.name = 'widget')",
com.acme.Order.class);
When executed, this query will return a collection of all Order entities for items named “widget”.
The SqlResultSetMapping metadata annotation—which is designed to handle more complex
cases—can be used as an alternative here. See section 10.4.4 for the definition of the SqlResultSetMapping metadata annotation and related annotations.
For the query shown above, the SqlResultSetMapping metadata for the query result type might be
specified as follows:
@SqlResultSetMapping(
name="WidgetOrderResults",
[email protected](entityClass=com.acme.Order.class))
The same results as produced by the query above can then obtained by the following:
Query q = em.createNativeQuery(
"SELECT o.id, o.quantity, o.item " +
"FROM Order o, Item i " +
"WHERE (o.item = i.id) AND (i.name = 'widget')",
"WidgetOrderResults");
When multiple entities are returned by a SQL query or when the column names of the SQL result do not
correspond to those of the object/relational mapping metadata, a SqlResultSetMapping metadata
definition must be provided to specify the entity mapping.
4/2/13
154
JSR-338 Final Release
Oracle
Query APIs
Java Persistence 2.1, Final Release
Entity Operations
The following query and SqlResultSetMapping metadata illustrates the return of multiple entity
types. It assumes default metadata and column name defaults.
Query q = em.createNativeQuery(
"SELECT o.id, o.quantity, o.item, i.id, i.name, i.description "+
"FROM Order o, Item i " +
"WHERE (o.quantity > 25) AND (o.item = i.id)",
"OrderItemResults");
@SqlResultSetMapping(name="OrderItemResults",
entities={
@EntityResult(entityClass=com.acme.Order.class),
@EntityResult(entityClass=com.acme.Item.class)
})
When the column names of the SQL result do not correspond to those of the object/relational mapping
metadata, more explicit SQL result mapping metadata must be provided to enable the persistence provider runtime to map the JDBC results into the expected objects. This might arise, for example, when
column aliases must be used in the SQL SELECT clause when the SQL result would otherwise contain
multiple columns of the same name or when columns in the SQL result are the results of operators or
functions. The FieldResult annotation element within the EntityResult annotation is used to
specify the mapping of such columns to entity attributes.
The following example combining multiple entity types includes aliases in the SQL statement. This
requires that the column names be explicitly mapped to the entity fields corresponding to those columns. The FieldResult annotation is used for this purpose.
Query q = em.createNativeQuery(
"SELECT o.id AS order_id, " +
"o.quantity AS order_quantity, " +
"o.item AS order_item, " +
"i.id, i.name, i.description " +
"FROM Order o, Item i " +
"WHERE (order_quantity > 25) AND (order_item = i.id)",
"OrderItemResults");
@SqlResultSetMapping(name="OrderItemResults",
entities={
@EntityResult(entityClass=com.acme.Order.class, fields={
@FieldResult(name="id", column="order_id"),
@FieldResult(name="quantity", column="order_quantity"),
@FieldResult(name="item", column="order_item")}),
@EntityResult(entityClass=com.acme.Item.class)
})
When the returned entity type contains an embeddable class, the FieldResult element must use a
dot (“.”) notation to indicate which column maps to which field or property of the contained
embeddable.
JSR-338 Final Release
155
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Query APIs
Example:
Query q = em.createNativeQuery(
"SELECT c.id AS customer_id, " +
"c.street AS customer_street, " +
"c.city AS customer_city, " +
"c.state AS customer_state, " +
"c.status AS customer_status " +
"FROM Customer c " +
"WHERE c.status = 'GOLD' " ,
"CustomerResults");
@SqlResultSetMapping(name=”CustomerResults”,
entities={
@EntityResult(entityClass=com.acme.Customer.class,
fields={
@FieldResult(name="id",
column="customer_id"),
@FieldResult(name="address.street",
column="customer_street"),
@FieldResult(name="address.city",
column="customer_city"),
@FieldResult(name="address.state",
column="customer_state"),
@FieldResult(name="status",
column="customer_status")})
})
When the returned entity type is the owner of a single-valued relationship and the foreign key is a composite foreign key (composed of multiple columns), a FieldResult element should be used for each
of the foreign key columns. The FieldResult element must use the dot (“.”) notation form to indicate the column that maps to each property or field of the target entity primary key.
If the target entity has a primary key of type IdClass, this specification takes the form of the name of
the field or property for the relationship, followed by a dot (“.”), followed by the name of the field or
property of the primary key in the target entity. The latter will be annotated with Id, as specified in section 11.1.22.
Example:
Query q = em.createNativeQuery(
"SELECT o.id AS order_id, " +
"o.quantity AS order_quantity, " +
"o.item_id AS order_item_id, " +
"o.item_name AS order_item_name, " +
"i.id, i.name, i.description " +
"FROM Order o, Item i " +
"WHERE (order_quantity > 25) AND (order_item_id = i.id) " +
"AND (order_item_name = i.name)",
"OrderItemResults");
4/2/13
156
JSR-338 Final Release
Oracle
Query APIs
Java Persistence 2.1, Final Release
Entity Operations
@SqlResultSetMapping(name="OrderItemResults",
entities={
@EntityResult(entityClass=com.acme.Order.class, fields={
@FieldResult(name="id", column="order_id"),
@FieldResult(name="quantity", column="order_quantity"),
@FieldResult(name="item.id", column="order_item_id")}),
@FieldResult(name="item.name",
column="order_item_name")}),
@EntityResult(entityClass=com.acme.Item.class)
})
If the target entity has a primary key of type EmbeddedId, this specification is composed of the name
of the field or property for the relationship, followed by a dot (“.”), followed by the name or the field or
property of the primary key (i.e., the name of the field or property annotated as EmbeddedId), followed by the name of the corresponding field or property of the embedded primary key class.
Example:
Query q = em.createNativeQuery(
"SELECT o.id AS order_id, " +
"o.quantity AS order_quantity, " +
"o.item_id AS order_item_id, " +
"o.item_name AS order_item_name, " +
"i.id, i.name, i.description " +
"FROM Order o, Item i " +
"WHERE (order_quantity > 25) AND (order_item_id = i.id) AND
(order_item_name = i.name)",
"OrderItemResults");
@SqlResultSetMapping(name="OrderItemResults",
entities={
@EntityResult(entityClass=com.acme.Order.class, fields={
@FieldResult(name="id", column="order_id"),
@FieldResult(name="quantity", column="order_quantity"),
@FieldResult(name="item.itemPk.id",
column="order_item_id")}),
@FieldResult(name="item.itemPk.name",
column="order_item_name")}),
@EntityResult(entityClass=com.acme.Item.class)
})
The FieldResult elements for the composite foreign key are combined to form the primary key
EmbeddedId class for the target entity. This may then be used to subsequently retrieve the entity if
the relationship is to be eagerly loaded.
The dot-notation form is not required to be supported for any usage other than for embeddables, composite foreign keys, or composite primary keys.
3.10.16.2 Returning Unmanaged Instances
Instances of other classes (including non-managed entity instances) as well as scalar results can be
returned by a native query. These can be used singly, or in combination, including with entity results.
JSR-338 Final Release
157
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Query APIs
3.10.16.2.1 Scalar Results
Scalar results can be included in the query result by specifying the ColumnResult annotation element of the SqlResultSetMapping annotation. The intended type of the result can be specified
using the type element of the ColumnResult annotation.
Query q = em.createNativeQuery(
"SELECT o.id AS order_id, " +
"o.quantity AS order_quantity, " +
"o.item AS order_item, " +
"i.name AS item_name, " +
"i.availabilityDate AS item_shipdate " +
"FROM Order o, Item i " +
"WHERE (order_quantity > 25) AND (order_item = i.id)",
"OrderResults");
@SqlResultSetMapping(name="OrderResults",
entities={
@EntityResult(entityClass=com.acme.Order.class, fields={
@FieldResult(name="id", column="order_id"),
@FieldResult(name="quantity", column="order_quantity"),
@FieldResult(name="item", column="order_item")})},
columns={
@ColumnResult(name="item_name"),
@ColumnResult(name="item_shipdate",
type=java.util.Date.class)}
)
3.10.16.2.2 Constructor Results
The mapping to constructors is specified using the ConstructorResult annotation element of the
SqlResultSetMapping annotation. The targetClass element of the ConstructorResult
annotation specifies the class whose constructor corresponds to the specified columns. All columns corresponding to arguments of the intended constructor must be specified using the columns element of
the ConstructorResult annotation in the same order as that of the argument list of the constructor.
Any entities returned as constructor results will be in either the new or the detached state, depending on
whether a primary key is retrieved for the constructed object.
4/2/13
158
JSR-338 Final Release
Oracle
Query APIs
Java Persistence 2.1, Final Release
Entity Operations
Example:
Query q = em.createNativeQuery(
"SELECT c.id, c.name, COUNT(o) as orderCount, AVG(o.price) AS
avgOrder " +
"FROM Customer c, Orders o " +
"WHERE o.cid = c.id " +
"GROUP BY c.id, c.name",
"CustomerDetailsResult");
@SqlResultSetMapping(name="CustomerDetailsResult",
classes={
@ConstructorResult(targetClass=com.acme.CustomerDetails.class,
columns={
@ColumnResult(name="id"),
@ColumnResult(name="name"),
@ColumnResult(name="orderCount"),
@ColumnResult(name="avgOrder", type=Double.class)})
})
3.10.16.3 Combinations of Result Types
When a SqlResultSetMapping specifies more than one mapping type (i.e., more than one of
EntityResult, ConstructorResult, ColumnResult), then for each row in the SQL result,
the query execution will result in an Object[] instance whose elements are as follows, in order: any
entity results (in the order in which they are defined in the entities element); any instances of
classes corresponding to constructor results (in the order defined in the classes element); and any
instances corresponding to column results (in the order defined in the columns element). If there are
any columns whose result mappings have not been specified, they are ignored.
3.10.16.4 Restrictions
When an entity is being returned, the SQL statement should select all of the columns that are mapped to
the entity object. This should include foreign key columns to related entities. The results obtained
when insufficient data is available are undefined. A SQL result set mapping must not be used to map
results to the non-persistent state of an entity.
The use of named parameters is not defined for native SQL queries. Only positional parameter binding
for SQL queries may be used by portable applications.
3.10.17 Stored Procedures
The StoredProcedureQuery interface supports the use of database stored procedures.
Stored procedures can be specified either by means of the NamedStoredProcedureQuery annotation or dynamically. Annotations for the specification of stored procedures are described in section
10.4.3.
JSR-338 Final Release
159
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Query APIs
3.10.17.1 Named Stored Procedure Queries
Unlike in the case of a named native query, the NamedStoredProcedureQuery annotation names
a stored procedure that exists in the database rather than providing a stored procedure definition. The
NamedStoredProcedureQuery annotation specifies the types of all parameters to the stored procedure, their corresponding parameter modes (IN, OUT, INOUT, REF_CURSOR[55]), and how result
sets, if any, are to be mapped. The name that is assigned to the stored procedure in the NamedStoredProcedureQuery annotation is passed as an argument to the createNamedStoredProcedureQuery method to create an executable StoredProcedureQuery object.
A stored procedure may return more than one result set. As with native queries, the mapping of result
sets can be specified either in terms of a resultClasses or as a resultSetMappings annotation element. If there are multiple result sets, it is assumed that they will be mapped using the same
mechanism — e.g., all via a set of result class mappings or all via a set of result set mappings. The
order of the specification of these mappings must be the same as the order in which the result sets will
be returned by the stored procedure invocation. If the stored procedure returns one or more result sets
and no resultClasses or resultSetMappings element has been specified, any result set will
be returned as a list of type Object[]. The combining of different strategies for the mapping of
stored procedure result sets is undefined.
StoredProcedureParameter metadata needs to be provided for all parameters. Parameters must
be specified in the order in which they occur in the parameter list of the stored procedure. If parameter
names are used, the parameter name is used to bind the parameter value and to extract the output value
(if the parameter is an INOUT or OUT parameter). If parameter names are not specified, it is assumed
that positional parameters are used. The mixing of named and positional parameters is undefined.
3.10.17.2 Dynamically-specified Stored Procedure Queries
If the stored procedure is not defined using metadata, parameter and result set information must be provided dynamically.
All parameters of a dynamically-specified stored procedure query must be registered using the registerStoredProcedureParameter method of the StoredProcedureQuery interface.
Result set mapping information can be provided by means of the createStoredProcedureQuery method.
3.10.17.3 Stored Procedure Query Execution
Stored procedure query execution can be controlled as described below.
The setParameter methods are used to set the values of all required IN and INOUT parameters. It
is not required to set the values of stored procedure parameters for which default values have been
defined by the stored procedure.
When getResultList and getSingleResult are called on a StoredProcedureQuery
object, the persistence provider will call execute on an unexecuted stored procedure query before
processing getResultList or getSingleResult.
[55] Note that REF_CURSOR parameters are used by some databases to return result sets from stored procedures.
4/2/13
160
JSR-338 Final Release
Oracle
Summary of Exceptions
Java Persistence 2.1, Final Release
Entity Operations
When executeUpdate is called on a StoredProcedureQuery object, the persistence provider
will call execute on an unexecuted stored procedure query followed by getUpdateCount. The
results of executeUpdate will be those of getUpdateCount.
The execute method supports both the simple case where scalar results are passed back only via
INOUT and OUT parameters as well as the most general case (multiple result sets and/or update counts,
possibly also in combination with output parameter values).
The execute method returns true if the first result is a result set, and false if it is an update count
or there are no results other than through INOUT and OUT parameters, if any.
If the execute method returns true, the pending result set can be obtained by calling getResultList or getSingleResult. The hasMoreResults method can then be used to test for
further results.
If execute or hasMoreResults returns false, the getUpdateCount method can be called to
obtain the pending result if it is an update count. The getUpdateCount method will return either the
update count (zero or greater) or -1 if there is no update count (i.e., either the next result is a result set or
there is no next update count).
For portability, results that correspond to JDBC result sets and update counts need to be processed
before the values of any INOUT or OUT parameters are extracted.
After results returned through getResultList and getUpdateCount have been exhausted,
results returned through INOUT and OUT parameters can be retrieved.
The getOutputParameterValue methods are used to retrieve the values passed back from the
procedure through INOUT and OUT parameters.
When using REF_CURSOR parameters for result sets, the update counts should be exhausted before
calling getResultList to retrieve the result set. Alternatively, the REF_CURSOR result set can be
retrieved through getOutputParameterValue. Result set mappings will be applied to results corresponding to REF_CURSOR parameters in the order the REF_CURSOR parameters were registered
with the query.
In the simplest case, where results are returned only via INOUT and OUT parameters, execute can be
followed immediately by calls to getOutputParameterValue.
3.11 Summary of Exceptions
The following is a summary of the exceptions defined by this specification:
PersistenceException
The PersistenceException is thrown by the persistence provider when a problem
occurs. It may be thrown to report that the invoked operation could not complete because of an
unexpected error (e.g., failure of the persistence provider to open a database connection).
JSR-338 Final Release
161
4/2/13
Oracle
Entity Operations
Java Persistence 2.1, Final Release
Summary of Exceptions
All other exceptions defined by this specification are subclasses of the PersistenceException. All instances of PersistenceException except for instances of NoResultException, NonUniqueResultException, LockTimeoutException, and
QueryTimeoutException will cause the current transaction, if one is active and the persistence context has been joined to it, to be marked for rollback.
TransactionRequiredException
The TransactionRequiredException is thrown by the persistence provider when a
transaction is required but is not active.
OptimisticLockException
The OptimisticLockException is thrown by the persistence provider when an optimistic locking conflict occurs. This exception may be thrown as part of an API call, at flush, or at
commit time. The current transaction, if one is active, will be marked for rollback.
PessimisticLockException
The PessimisticLockException is thrown by the persistence provider when a pessimistic locking conflict occurs. The current transaction will be marked for rollback. Typically
the PessimisticLockException occurs because the database transaction has been
rolled back due to deadlock or because the database uses transaction-level rollback when a pessimistic lock cannot be granted.
LockTimeoutException
The LockTimeoutException is thrown by the persistence provider when a pessimistic
locking conflict occurs that does not result in transaction rollback. Typically this occurs
because the database uses statement-level rollback when a pessimistic lock cannot be granted
(and there is no deadlock). The LockTimeoutException does not cause the current transaction to be marked for rollback.
RollbackException
The RollbackException is thrown by the persistence provider when EntityTransaction.commit fails.
EntityExistsException
The EntityExistsException may thrown by the persistence provider when the persist operation is invoked and the entity already exists. The EntityExistsException
may be thrown when the persist operation is invoked, or the EntityExistsException or
another PersistenceException may be thrown at commit time. The current transaction,
if one is active and the persistence context has been joined to it, will be marked for rollback.
EntityNotFoundException
The EntityNotFoundException is thrown by the persistence provider when an entity
reference obtained by getReference is accessed but the entity does not exist. It is thrown
4/2/13
162
JSR-338 Final Release
Oracle
Summary of Exceptions
Java Persistence 2.1, Final Release
Entity Operations
by the refresh operation when the entity no longer exists in the database. It is also thrown
by the lock operation when pessimistic locking is used and the entity no longer exists in the
database. The current transaction, if one is active and the persistence context has been joined to
it, will be marked for rollback.
NoResultException
The NoResultException is thrown by the persistence provider when Query.getSingleResult or TypedQuery.getSingleResult is invoked and there is no result to
return. This exception will not cause the current transaction, if one is active, to be marked for
rollback.
NonUniqueResultException
The NonUniqueResultException is thrown by the persistence provider when
Query.getSingleResult or TypedQuery.getSingleResult is invoked and there
is more than one result from the query. This exception will not cause the current transaction, if
one is active, to be marked for rollback.
QueryTimeoutException
The QueryTimeoutException is thrown by the persistence provider when a query times
out and only the statement is rolled back. The QueryTimeoutException does not cause
the current transaction, if one is active, to be marked for rollback.
JSR-338 Final Release
163
4/2/13
Oracle
Entity Operations
4/2/13
Java Persistence 2.1, Final Release
Summary of Exceptions
164
JSR-338 Final Release
Oracle
Overview
Ch apt er 4
Java Persistence 2.1, Final Release
Query Language
Query Language
The Java Persistence query language is a string-based query language used to define queries over entities and their persistent state. It enables the application developer to specify the semantics of queries in
a portable way, independent of the particular database schema in use in an enterprise environment. The
full range of the language may be used in both static and dynamic queries.
This chapter provides the full definition of the Java Persistence query language.
4.1 Overview
The Java Persistence query language is a query specification language for string-based dynamic queries
and static queries expressed through metadata. It is used to define queries over the persistent entities
defined by this specification and their persistent state and relationships.
The Java Persistence query language can be compiled to a target language, such as SQL, of a database
or other persistent store. This allows the execution of queries to be shifted to the native language facilities provided by the database, instead of requiring queries to be executed on the runtime representation
of the entity state. As a result, query methods can be optimizable as well as portable.
JSR-338 Final Release
165
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final Release
Statement Types
The query language uses the abstract persistence schema of entities, including their embedded objects
and relationships, for its data model, and it defines operators and expressions based on this data model.
It uses a SQL-like syntax to select objects or values based on abstract schema types and relationships. It
is possible to parse and validate queries before entities are deployed.
The term abstract persistence schema refers to the persistent schema abstraction (persistent
entities, their state, and their relationships) over which Java Persistence queries operate.
Queries over this persistent schema abstraction are translated into queries that are executed
over the database schema to which entities are mapped.
Queries may be defined in metadata annotations or the XML descriptor. The abstract schema types of a
set of entities can be used in a query if the entities are defined in the same persistence unit as the query.
Path expressions allow for navigation over relationships defined in the persistence unit.
A persistence unit defines the set of all classes that are related or grouped by the application
and which must be colocated in their mapping to a single database.
4.2 Statement Types
A Java Persistence query language statement may be either a select statement, an update statement, or a
delete statement.
This chapter refers to all such statements as “queries”. Where it is important to distinguish
among statement types, the specific statement type is referenced.
In BNF syntax, a query language statement is defined as:
QL_statement :: = select_statement | update_statement | delete_statement
Any Java Persistence query language statement may be constructed dynamically or may be statically
defined in a metadata annotation or XML descriptor element.
All statement types may have parameters.
4.2.1 Select Statements
A select statement is a string which consists of the following clauses:
• a SELECT clause, which determines the type of the objects or values to be selected.
• a FROM clause, which provides declarations that designate the domain to which the expressions specified in the other clauses of the query apply.
• an optional WHERE clause, which may be used to restrict the results that are returned by the
query.
4/2/13
166
JSR-338 Final Release
Oracle
Abstract Schema Types and Query Domains
Java Persistence 2.1, Final Release
Query Language
• an optional GROUP BY clause, which allows query results to be aggregated in terms of
groups.
• an optional HAVING clause, which allows filtering over aggregated groups.
• an optional ORDER BY clause, which may be used to order the results that are returned by the
query.
In BNF syntax, a select statement is defined as:
select_statement :: = select_clause from_clause [where_clause] [groupby_clause]
[having_clause] [orderby_clause]
A select statement must always have a SELECT and a FROM clause. The square brackets [] indicate
that the other clauses are optional.
4.2.2 Update and Delete Statements
Update and delete statements provide bulk operations over sets of entities.
In BNF syntax, these operations are defined as:
update_statement :: = update_clause [where_clause]
delete_statement :: = delete_clause [where_clause]
The update and delete clauses determine the type of the entities to be updated or deleted. The WHERE
clause may be used to restrict the scope of the update or delete operation.
Update and delete statements are described further in Section 4.10.
4.3 Abstract Schema Types and Query Domains
The Java Persistence query language is a typed language, and every expression has a type. The type of
an expression is derived from the structure of the expression, the abstract schema types of the identification variable declarations, the types to which the persistent attributes evaluate, and the types of literals.
The abstract schema type of an entity or embeddable is derived from its class and the metadata information provided by Java language annotations or in the XML descriptor.
Informally, the abstract schema type of an entity or embeddable can be characterized as follows:
• For every non-relationship persistent field or get accessor method (for a persistent property)
of the class, there is a field (“state field”) whose abstract schema type corresponds to that of
the field or the result type of the accessor method.
JSR-338 Final Release
167
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final Release
Abstract Schema Types and Query Domains
• For every persistent relationship field or get accessor method (for a persistent relationship
property) of the class, there is a field (“association field”) whose type is the abstract schema
type of the related entity (or, if the relationship is a one-to-many or many-to-many, a collection
of such).
Abstract schema types are specific to the query language data model. The persistence provider is not
required to implement or otherwise materialize an abstract schema type.
The domain of a query consists of the abstract schema types of all entities and embeddables that are
defined in the same persistence unit.
The domain of a query may be restricted by the navigability of the relationships of the entity and associated embeddable classes on which it is based. The association fields of an entity’s or embeddable’s
abstract schema type determine navigability. Using the association fields and their values, a query can
select related entities and use their abstract schema types in the query.
4.3.1 Naming
Entities are designated in query strings by their entity names. The entity name is defined by the name
element of the Entity annotation (or the entity-name XML descriptor element), and defaults to
the unqualified name of the entity class. Entity names are scoped within the persistence unit and must be
unique within the persistence unit.
4.3.2 Example
This example assumes that the application developer provides several entity classes, representing
orders, products, and line items, and an embeddable address class representing shipping addresses and
billing addresses. The abstract schema types for the entities are Order, Product, and LineItem
respectively. There is a one-to-many relationship between Order and LineItem. The entity
LineItem is related to Product in a many-to-one relationship. The classes are logically in the same
persistence unit, as shown in Figure 1.
Queries to select orders can be defined by navigating over the association fields and state fields defined
by Order and LineItem. A query to find all orders with pending line items might be written as follows:
SELECT DISTINCT o
FROM Order AS o JOIN o.lineItems AS l
WHERE l.shipped = FALSE
4/2/13
168
JSR-338 Final Release
Oracle
Abstract Schema Types and Query Domains
Figure 1
Java Persistence 2.1, Final Release
Query Language
Abstract Persistence Schema of Several Entities with Defined in the Same Persistence Unit.
Order
1
m
LineItem
m
1
Product
Shipping
Address
Billing
Address
This query navigates over the association field lineItems of the abstract schema type Order to find
line items, and uses the state field shipped of LineItem to select those orders that have at least one
line item that has not yet shipped. (Note that this query does not select orders that have no line items.)
Although reserved identifiers, such as DISTINCT, FROM, AS, JOIN, WHERE, and FALSE appear in
upper case in this example, reserved identifiers are case insensitive.[56]
The SELECT clause of this example designates the return type of this query to be of type Order.
Because the same persistence unit defines the abstract persistence schema of the related entities, the
developer can also specify a query over orders that utilizes the abstract schema type for products, and
hence the state fields and association fields of both the abstract schema types Order and Product.
For example, if the abstract schema type Product has a state field named productType, a query
over orders can be specified using this state field. Such a query might be to find all orders for products
with product type office supplies. A query for this might be as follows.
SELECT DISTINCT o
FROM Order o JOIN o.lineItems l JOIN l.product p
WHERE p.productType = ‘office_supplies’
Because Order is related to Product by means of the relationships between Order and LineItem
and between LineItem and Product, navigation using the association fields lineItems and
product is used to express the query. This query is specified by using the entity name Order, which
designates the abstract schema type over which the query ranges. The basis for the navigation is provided by the association fields lineItems and product of the abstract schema types Order and
LineItem respectively.
[56] This chapter uses the convention that reserved identifiers appear in upper case in the examples and BNF for the language.
JSR-338 Final Release
169
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final ReleaseThe FROM Clause and Navigational Declarations
4.4 The FROM Clause and Navigational Declarations
The FROM clause of a query defines the domain of the query by declaring identification variables. An
identification variable is an identifier declared in the FROM clause of a query. The domain of the query
may be constrained by path expressions. (See section 4.4.4.)
Identification variables designate instances of a particular abstract schema type. The FROM clause can
contain multiple identification variable declarations separated by a comma (,).
from_clause ::=
FROM identification_variable_declaration
{, {identification_variable_declaration | collection_member_declaration}}*
identification_variable_declaration ::= range_variable_declaration { join | fetch_join }*
range_variable_declaration ::= entity_name [AS] identification_variable
join ::= join_spec join_association_path_expression [AS] identification_variable
[join_condition]
fetch_join ::= join_spec FETCH join_association_path_expression
join_association_path_expression ::=
join_collection_valued_path_expression |
join_single_valued_path_expression |
TREAT(join_collection_valued_path_expression AS subtype) |
TREAT(join_single_valued_path_expression AS subtype)
join_collection_valued_path_expression::=
identification_variable.{single_valued_embeddable_object_field.}*collection_valued_field
join_single_valued_path_expression::=
identification_variable.{single_valued_embeddable_object_field.}*single_valued_object_field
join_spec ::= [ LEFT [OUTER] | INNER ] JOIN
join_condition ::= ON conditional_expression
collection_member_declaration ::=
IN (collection_valued_path_expression) [AS] identification_variable
The following subsections discuss the constructs used in the FROM clause.
4.4.1 Identifiers
An identifier is a character sequence of unlimited length. The character sequence must begin with a Java
identifier start character, and all other characters must be Java identifier part characters. An identifier
start character is any character for which the method Character.isJavaIdentifierStart
returns true. This includes the underscore (_) character and the dollar sign ($) character. An identifier
part character is any character for which the method Character.isJavaIdentifierPart
returns true. The question mark (?) character is reserved for use by the Java Persistence query language.
4/2/13
170
JSR-338 Final Release
Oracle
The FROM Clause and Navigational DeclarationsJava Persistence 2.1, Final Release
Query Language
The following are reserved identifiers: ABS, ALL, AND, ANY, AS, ASC, AVG, BETWEEN,
BIT_LENGTH[57], BOTH, BY, CASE, CHAR_LENGTH, CHARACTER_LENGTH, CLASS, COALESCE, CONCAT, COUNT, CURRENT_DATE, CURRENT_TIME, CURRENT_TIMESTAMP,
DELETE, DESC, DISTINCT, ELSE, EMPTY, END, ENTRY, ESCAPE, EXISTS, FALSE, FETCH,
FROM, FUNCTION, GROUP, HAVING, IN, INDEX, INNER, IS, JOIN, KEY, LEADING, LEFT,
LENGTH, LIKE, LOCATE, LOWER, MAX, MEMBER, MIN, MOD, NEW, NOT, NULL, NULLIF,
OBJECT, OF, ON, OR, ORDER, OUTER, POSITION, SELECT, SET, SIZE, SOME, SQRT, SUBSTRING, SUM, THEN, TRAILING, TREAT, TRIM, TRUE, TYPE, UNKNOWN, UPDATE, UPPER,
VALUE, WHEN, WHERE.
Reserved identifiers are case insensitive. Reserved identifiers must not be used as identification variables or result variables (see section 4.8).
It is recommended that SQL key words other than those listed above not be used as identification variables in queries because they may be used as reserved identifiers in future releases of
this specification.
4.4.2 Identification Variables
An identification variable is a valid identifier declared in the FROM clause of a query.
All identification variables must be declared in the FROM clause. Identification variables cannot be
declared in other clauses.
An identification variable must not be a reserved identifier or have the same name as any entity in the
same persistence unit.
Identification variables are case insensitive.
An identification variable evaluates to a value of the type of the expression used in declaring the variable. For example, consider the previous query:
SELECT DISTINCT o
FROM Order o JOIN o.lineItems l JOIN l.product p
WHERE p.productType = ‘office_supplies’
In the FROM clause declaration o.lineItems l, the identification variable l evaluates to any
LineItem value directly reachable from Order. The association field lineItems is a collection of
instances of the abstract schema type LineItem and the identification variable l refers to an element
of this collection. The type of l is the abstract schema type of LineItem.
An identification variable can range over an entity, embeddable, or basic abstract schema type. An identification variable designates an instance of an abstract schema type or an element of a collection of
abstract schema type instances.
[57] BIT_LENGTH, CHAR_LENGTH, CHARACTER_LENGTH, POSITION, and UNKNOWN are not currently used: they are
reserved for future use.
JSR-338 Final Release
171
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final ReleaseThe FROM Clause and Navigational Declarations
Note that for identification variables referring to an instance of an association or collection represented
as a java.util.Map, the identification variable is of the abstract schema type of the map value.
An identification variable always designates a reference to a single value. It is declared in one of three
ways: in a range variable declaration, in a join clause, or in a collection member declaration. The identification variable declarations are evaluated from left to right in the FROM clause, and an identification
variable declaration can use the result of a preceding identification variable declaration of the query
string.
All identification variables used in the SELECT, WHERE, ORDER BY, GROUP BY, or HAVING
clause of a SELECT or DELETE statement must be declared in the FROM clause. The identification
variables used in the WHERE clause of an UPDATE statement must be declared in the UPDATE clause.
Identification variables are existentially quantified in these clauses. This means that an identification
variable represents a member of a collection or an instance of an entity’s abstract schema type. An identification variable never designates a collection in its entirety.
An identification variable is scoped to the query (or subquery) in which it is defined and is also visible
to any subqueries within that query scope that do not define an identification variable of the same name.
4.4.3 Range Variable Declarations
The syntax for declaring an identification variable as a range variable is similar to that of SQL; optionally, it uses the AS keyword. A range variable designates an entity abstract schema type.[58]
range_variable_declaration ::= entity_name [AS] identification_variable
Range variable declarations allow the developer to designate a “root” for objects which may not be
reachable by navigation.
In order to select values by comparing more than one instance of an entity abstract schema type, more
than one identification variable ranging over the abstract schema type is needed in the FROM clause.
The following query returns orders whose quantity is greater than the order quantity for John Smith.
This example illustrates the use of two different identification variables in the FROM clause, both of the
abstract schema type Order. The SELECT clause of this query determines that it is the orders with
quantities larger than John Smith’s that are returned.
SELECT DISTINCT o1
FROM Order o1, Order o2
WHERE o1.quantity > o2.quantity AND
o2.customer.lastname = ‘Smith’ AND
o2.customer.firstname= ‘John’
[58] A range variable must not designate an embeddable class abstract schema type.
4/2/13
172
JSR-338 Final Release
Oracle
The FROM Clause and Navigational DeclarationsJava Persistence 2.1, Final Release
Query Language
4.4.4 Path Expressions
An identification variable followed by the navigation operator (.) and a state field or association field is
a path expression. The type of the path expression is the type computed as the result of navigation; that
is, the type of the state field or association field to which the expression navigates. The type of a path
expression that navigates to an association field may be specified as a subtype of the declared type of
the association field by means of the TREAT operator. See section 4.4.9.
An identification variable qualified by the KEY, VALUE, or ENTRY operator is a path expression. The
KEY, VALUE, and ENTRY operators may only be applied to identification variables that correspond to
map-valued associations or map-valued element collections. The type of the path expression is the type
computed as the result of the operation; that is, the abstract schema type of the field that is the value of
the KEY, VALUE, or ENTRY operator (the map key, map value, or map entry respectively).[59]
In the following query, photos is a map from photo label to filename.
SELECT i.name, VALUE(p)
FROM Item i JOIN i.photos p
WHERE KEY(p) LIKE ‘%egret’
In the above query the identification variable p designates an abstract schema type corresponding to the
map value. The results of VALUE(p) and KEY(p) are the map value and the map key associated with
p, respectively. The following query is equivalent:
SELECT i.name, p
FROM Item i JOIN i.photos p
WHERE KEY(p) LIKE ‘%egret’
A path expression using the KEY or VALUE operator can be further composed. A path expression
using the ENTRY operator is terminal. It cannot be further composed and can only appear in the
SELECT list of a query.
The syntax for qualified identification variables is as follows.
qualified_identification_variable :: =
map_field_identification_variable |
ENTRY(identification_variable)
map_field_identification_variable :: =
KEY(identification_variable) |
VALUE(identification_variable)
Depending on navigability, a path expression that leads to an association field or to a field whose type is
an embeddable class may be further composed. Path expressions can be composed from other path
expressions if the original path expression evaluates to a single-valued type (not a collection).
[59] Note that use of VALUE is optional, as an identification variable referring to an association of type java.util.Map is of the
abstract schema type of the map value. (See section 4.4.2.)
JSR-338 Final Release
173
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final ReleaseThe FROM Clause and Navigational Declarations
In the following example, contactInfo denotes an embeddable class consisting of an address and
set of phones. Phone is an entity.
SELECT p.vendor
FROM Employee e JOIN e.contactInfo.phones p
WHERE e.contactInfo.address.zipcode = '95054'
Path expression navigability is composed using “inner join” semantics. That is, if the value of a non-terminal field in the path expression is null, the path is considered to have no value, and does not participate in the determination of the result.
The following query is equivalent to the query above:
SELECT p.vendor
FROM Employee e JOIN e.contactInfo c JOIN c.phones p
WHERE e.contactInfo.address.zipcode = '95054'
4.4.4.1 Path Expression Syntax
The syntax for single-valued path expressions and collection-valued path expressions is as follows.
An identification variable used in a single_valued_object_path_expression or in a
collection_valued_path_expression may be an unqualified identification variable or an identification variable to which the KEY or VALUE function has been applied.
general_identification_variable ::=
identification_variable |
map_field_identification_variable
The type of an entity-valued path expression or an entity-valued subpath of a path expression used in a
WHERE clause may be specified as a subtype of the corresponding declared type by means of the
TREAT operator. See section 4.4.9.
general_subpath ::= simple_subpath | treated_subpath{.single_valued_object_field}*
simple_subpath ::=
general_identification_variable |
general_identification_variable{.single_valued_object_field}*
treated_subpath ::= TREAT(general_subpath AS subtype)
single_valued_path_expression ::=
qualified_identification_variable |
TREAT(qualified_identification_variable AS subtype) |
state_field_path_expression |
single_valued_object_path_expression
state_field_path_expression ::= general_subpath.state_field
4/2/13
174
JSR-338 Final Release
Oracle
The FROM Clause and Navigational DeclarationsJava Persistence 2.1, Final Release
Query Language
state_valued_path_expression ::=
state_field_path_expression | general_identification_variable
single_valued_object_path_expression ::= general_subpath.single_valued_object_field
collection_valued_path_expression ::= general_subpath.collection_valued_field
A single_valued_object_field is designated by the name of an association field in a one-to-one or
many-to-one relationship or a field of embeddable class type. The type of a
single_valued_object_field is the abstract schema type of the related entity or embeddable class.
A state _field is designated by the name of an entity or embeddable class state field that corresponds to
a basic type.
A collection_valued_field is designated by the name of an association field in a one-to-many or a
many-to-many relationship or by the name of an element collection field. The type of a
collection_valued_field is a collection of values of the abstract schema type of the related entity or element type.
It is syntactically illegal to compose a path expression from a path expression that evaluates to a collection. For example, if o designates Order, the path expression o.lineItems.product is illegal
since navigation to lineItems results in a collection. This case should produce an error when the
query string is verified. To handle such a navigation, an identification variable must be declared in the
FROM clause to range over the elements of the lineItems collection. Another path expression must
be used to navigate over each such element in the WHERE clause of the query, as in the following:
SELECT DISTINCT l.product
FROM Order AS o JOIN o.lineItems l
It is illegal to use a collection_valued_path_expression other than in the FROM clause of a query
except in an empty_collection_comparison_expression, in a collection_member_expression, or
as an argument to the SIZE operator. See Sections 4.6.12, 4.6.13, and 4.6.17.2.2.
4.4.5 Joins
An inner join may be implicitly specified by the use of a cartesian product in the FROM clause and a
join condition in the WHERE clause. In the absence of a join condition, this reduces to the cartesian
product.
The main use case for this generalized style of join is when a join condition does not involve a foreign
key relationship that is mapped to an entity relationship.
Example:
SELECT c FROM Customer c, Employee e WHERE c.hatsize = e.shoesize
In general, use of this style of inner join (also referred to as theta-join) is less typical than explicitly
defined joins over relationships.
JSR-338 Final Release
175
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final ReleaseThe FROM Clause and Navigational Declarations
The syntax for explicit join operations is as follows:
join::= join_spec join_association_path_expression [AS] identification_variable [join_condition]
fetch_join ::= join_spec FETCH join_association_path_expression
join_association_path_expression ::=
join_collection_valued_path_expression |
join_single_valued_path_expression |
TREAT(join_collection_valued_path_expression AS subtype) |
TREAT(join_single_valued_path_expression AS subtype)
join_collection_valued_path_expression::=
identification_variable.{single_valued_embeddable_object_field.}*collection_valued_field
join_single_valued_path_expression::=
identification_variable.{single_valued_embeddable_object_field.}*single_valued_object_field
join_spec::= [ LEFT [OUTER] | INNER ] JOIN
join_condition ::= ON conditional_expression
The inner and outer join operation types described in sections 4.4.5.1, 4.4.5.2, and 4.4.5.3 are supported.
4.4.5.1 Inner Joins (Relationship Joins)
The syntax for the inner join operation is
[ INNER ] JOIN join_association_path_expression [AS] identification_variable [join_condition]
For example, the query below joins over the relationship between customers and orders. This type of
join typically equates to a join over a foreign key relationship in the database.
SELECT c FROM Customer c JOIN c.orders o WHERE c.status = 1
The keyword INNER may optionally be used:
SELECT c FROM Customer c INNER JOIN c.orders o WHERE c.status = 1
This is equivalent to the following query using the earlier IN construct, defined in [7]. It selects those
customers of status 1 for which at least one order exists:
SELECT OBJECT(c) FROM Customer c, IN(c.orders) o WHERE c.status = 1
The query below joins over Employee, ContactInfo and Phone. ContactInfo is an
embeddable class that consists of an address and set of phones. Phone is an entity.
SELECT p.vendor
FROM Employee e JOIN e.contactInfo c JOIN c.phones p
WHERE c.address.zipcode = '95054'
A join condition may be specified for an inner join. This is equivalent to specification of the same condition in the WHERE clause.
4/2/13
176
JSR-338 Final Release
Oracle
The FROM Clause and Navigational DeclarationsJava Persistence 2.1, Final Release
Query Language
4.4.5.2 Left Outer Joins
LEFT JOIN and LEFT OUTER JOIN are synonymous. They enable the retrieval of a set of entities
where matching values in the join condition may be absent.
The syntax for a left outer join is
LEFT [OUTER] JOIN join_association_path_expression [AS] identification_variable
[join_condition]
An outer join without a specified join condition has an implicit join condition over the foreign key relationship corresponding to the join_association_path_expression. It would typically be mapped to a
SQL outer join with an ON condition on the foreign key relationship as in the queries below:
Java Persistence query language:
SELECT s.name, COUNT(p)
FROM Suppliers s LEFT JOIN s.products p
GROUP BY s.name
SQL:
SELECT s.name, COUNT(p.id)
FROM Suppliers s LEFT JOIN Products p
ON s.id = p.supplierId
GROUP By s.name
An outer join with an explicit ON condition would cause an additional specified join condition to be
added to the generated SQL:
Java Persistence query language:
SELECT s.name, COUNT(p)
FROM Suppliers s LEFT JOIN s.products p
ON p.status = 'inStock'
GROUP BY s.name
SQL:
SELECT s.name, COUNT(p.id)
FROM Suppliers s LEFT JOIN Products p
ON s.id = p.supplierId AND p.status = 'inStock'
GROUP BY s.name
Note that the result of this query will be different from that of the following query:
SELECT s.name, COUNT(p)
FROM Suppliers s LEFT JOIN s.products p
WHERE p.status = 'inStock'
GROUP BY s.name
The result of the latter query will exclude suppliers who have no products in stock whereas the former
query will include them.
JSR-338 Final Release
177
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final ReleaseThe FROM Clause and Navigational Declarations
An important use case for LEFT JOIN is in enabling the prefetching of related data items as a side effect
of a query. This is accomplished by specifying the LEFT JOIN as a FETCH JOIN as described below.
4.4.5.3 Fetch Joins
A FETCH JOIN enables the fetching of an association or element collection as a side effect of the execution of a query.
The syntax for a fetch join is
fetch_join ::= [ LEFT [OUTER] | INNER ] JOIN FETCH join_association_path_expression
The association referenced by the right side of the FETCH JOIN clause must be an association or element collection that is referenced from an entity or embeddable that is returned as a result of the query.
It is not permitted to specify an identification variable for the objects referenced by the right side of the
FETCH JOIN clause, and hence references to the implicitly fetched entities or elements cannot appear
elsewhere in the query.
The following query returns a set of departments. As a side effect, the associated employees for those
departments are also retrieved, even though they are not part of the explicit query result. The initialization of the persistent state or relationship fields or properties of the objects that are retrieved as a result
of a fetch join is determined by the metadata for that class—in this example, the Employee entity
class.
SELECT d
FROM Department d LEFT JOIN FETCH d.employees
WHERE d.deptno = 1
A fetch join has the same join semantics as the corresponding inner or outer join, except that the related
objects specified on the right-hand side of the join operation are not returned in the query result or otherwise referenced in the query. Hence, for example, if department 1 has five employees, the above query
returns five references to the department 1 entity.
The FETCH JOIN construct must not be used in the FROM clause of a subquery.
4.4.6 Collection Member Declarations
An identification variable declared by a collection_member_declaration ranges over values of a collection obtained by navigation using a path expression.
An identification variable of a collection member declaration is declared using a special operator, the
reserved identifier IN. The argument to the IN operator is a collection-valued path expression. The path
expression evaluates to a collection type specified as a result of navigation to a collection-valued association field of an entity or embeddable class abstract schema type.
The syntax for declaring a collection member identification variable is as follows:
collection_member_declaration ::=
IN (collection_valued_path_expression) [AS] identification_variable
4/2/13
178
JSR-338 Final Release
Oracle
The FROM Clause and Navigational DeclarationsJava Persistence 2.1, Final Release
Query Language
For example, the query
SELECT DISTINCT o
FROM Order o JOIN o.lineItems l
WHERE l.product.productType = ‘office_supplies’
can equivalently be expressed as follows, using the IN operator:
SELECT DISTINCT o
FROM Order o, IN(o.lineItems) l
WHERE l.product.productType = ‘office_supplies’
In this example, lineItems is the name of an association field whose value is a collection of
instances of the abstract schema type LineItem. The identification variable l designates a member of
this collection, a single LineItem abstract schema type instance. In this example, o is an identification variable of the abstract schema type Order.
4.4.7 FROM Clause and SQL
The Java Persistence query language treats the FROM clause similarly to SQL in that the declared identification variables affect the results of the query even if they are not used in the WHERE clause. Application developers should use caution in defining identification variables because the domain of the
query can depend on whether there are any values of the declared type.
For example, the FROM clause below defines a query over all orders that have line items and existing
products. If there are no Product instances in the database, the domain of the query is empty and no
order is selected.
SELECT o
FROM Order AS o JOIN o.lineItems l JOIN l.product p
4.4.8 Polymorphism
Java Persistence queries are automatically polymorphic. The FROM clause of a query designates not
only instances of the specific entity class(es) to which it explicitly refers but instances of subclasses of
those classes as well. The instances returned by a query thus include instances of the subclasses that satisfy the query criteria.
Non-polymorphic queries or queries whose polymorphism is restricted can be specified using entity
type expressions in the WHERE clause to restrict the domain of the query. See section 4.6.17.5.
4.4.9 Downcasting
The use of the TREAT operator is supported for downcasting within path expressions in the FROM and
WHERE clauses. Use of the TREAT operator allows access to subclass-specific state.
JSR-338 Final Release
179
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final Release
WHERE Clause
If during query execution the first argument to the TREAT operator is not a subtype (proper or
improper) of the target type, the path is considered to have no value, and does not participate in the
determination of the result. That is, in the case of a join, the referenced object does not participate in the
result, and in the case of a restriction, the associated predicate is false. Use of the TREAT operator
therefore also has the effect of filtering on the specified type (and its subtypes) as well as performing the
downcast. If the target type is not a subtype (proper or improper) of the static type of the first argument,
the query is invalid.
Examples:
SELECT b.name, b.ISBN
FROM Order o JOIN TREAT(o.product AS Book) b
SELECT e FROM Employee e JOIN TREAT(e.projects AS LargeProject) lp
WHERE lp.budget > 1000
SELECT e FROM Employee e JOIN e.projects p
WHERE TREAT(p AS LargeProject).budget > 1000
OR
TREAT(p AS SmallProject).name LIKE 'Persist%'
OR
p.description LIKE "cost overrun"
SELECT e FROM Employee e
WHERE TREAT(e AS Exempt).vacationDays > 10
OR TREAT(e AS Contractor).hours > 100
4.5 WHERE Clause
The WHERE clause of a query consists of a conditional expression used to select objects or values that
satisfy the expression. The WHERE clause restricts the result of a select statement or the scope of an
update or delete operation.
A WHERE clause is defined as follows:
where_clause ::= WHERE conditional_expression
The GROUP BY construct enables the aggregation of values according to the properties of an entity
class. The HAVING construct enables conditions to be specified that further restrict the query result as
restrictions upon the groups.
The syntax of the HAVING clause is as follows:
having_clause ::= HAVING conditional_expression
The GROUP BY and HAVING constructs are further discussed in Section 4.7.
4/2/13
180
JSR-338 Final Release
Oracle
Conditional Expressions
Java Persistence 2.1, Final Release
Query Language
4.6 Conditional Expressions
The following sections describe language constructs that can be used in a conditional expression of the
WHERE clause, the HAVING clause, or in an ON condition.
State fields that are mapped in serialized form or as lobs cannot be portably used in conditional expressions[60].
4.6.1 Literals
A string literal is enclosed in single quotes—for example: ‘literal’. A string literal that includes a single
quote is represented by two single quotes—for example: ‘literal’’s’. String literals in queries, like Java
String literals, use unicode character encoding. The use of Java escape notation is not supported in
query string literals.
Exact numeric literals support the use of Java integer literal syntax as well as SQL exact numeric literal
syntax.
Approximate literals support the use Java floating point literal syntax as well as SQL approximate
numeric literal syntax.
Appropriate suffixes can be used to indicate the specific type of a numeric literal in accordance with the
Java Language Specification. Support for the use of hexadecimal and octal numeric literals is not
required by this specification.
Enum literals support the use of Java enum literal syntax. The fully qualified enum class name must be
specified.
The JDBC escape syntax may be used for the specification of date, time, and timestamp literals. For
example:
SELECT o
FROM Customer c JOIN c.orders o
WHERE c.name = 'Smith'
AND o.submissionDate < {d '2008-12-31'}
The portability of this syntax for date, time, and timestamp literals is dependent upon the JDBC driver
in use. Persistence providers are not required to translate from this syntax into the native syntax of the
database or driver.
The boolean literals are TRUE and FALSE.
Entity type literals are specified by entity names—for example: Customer.
Although reserved literals appear in upper case, they are case insensitive.
[60] The implementation is not expected to perform such query operations involving such fields in memory rather than in the database.
JSR-338 Final Release
181
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final Release
Conditional Expressions
4.6.2 Identification Variables
All identification variables used in the WHERE or HAVING clause of a SELECT or DELETE statement must be declared in the FROM clause, as described in Section 4.4.2. The identification variables
used in the WHERE clause of an UPDATE statement must be declared in the UPDATE clause.
Identification variables are existentially quantified in the WHERE and HAVING clause. This means
that an identification variable represents a member of a collection or an instance of an entity’s abstract
schema type. An identification variable never designates a collection in its entirety.
4.6.3 Path Expressions
It is illegal to use a collection_valued_path_expression within a WHERE or HAVING clause as part
of a conditional expression except in an empty_collection_comparison_expression, in a
collection_member_expression, or as an argument to the SIZE operator.
4.6.4 Input Parameters
Either positional or named parameters may be used. Positional and named parameters must not be
mixed in a single query.
Input parameters can only be used in the WHERE clause or HAVING clause of a query or as the new
value for an update item in the SET clause of an update statement.
Note that if an input parameter value is null, comparison operations or arithmetic operations
involving the input parameter will return an unknown value. See Section 4.11.
All input parameters must be single-valued, except in IN expressions (see section 4.6.9), which support
the use of collection-valued input parameters.
The API for the binding of query parameters is described in Chapter 3.
4.6.4.1 Positional Parameters
The following rules apply to positional parameters.
• Input parameters are designated by the question mark (?) prefix followed by an integer. For
example: ?1.
• Input parameters are numbered starting from 1.
• The same parameter can be used more than once in the query string.
• The ordering of the use of parameters within the query string need not conform to the order of
the positional parameters.
4/2/13
182
JSR-338 Final Release
Oracle
Conditional Expressions
Java Persistence 2.1, Final Release
Query Language
4.6.4.2 Named Parameters
A named parameter is denoted by an identifier that is prefixed by the ":" symbol. It follows the rules for
identifiers defined in Section 4.4.1. Named parameters are case sensitive.
Example:
SELECT c
FROM Customer c
WHERE c.status = :stat
The same named parameter can be used more than once in the query string.
4.6.5 Conditional Expression Composition
Conditional expressions are composed of other conditional expressions, comparison operations, logical
operations, path expressions that evaluate to boolean values, boolean literals, and boolean input parameters.
The scalar expressions described in section 4.6.17 can be used in conditional expressions.
Aggregate functions can only be used in conditional expressions in a HAVING clause. See section 4.7.
Standard bracketing () for ordering expression evaluation is supported.
Conditional expressions are defined as follows:
conditional_expression ::= conditional_term | conditional_expression OR conditional_term
conditional_term ::= conditional_factor | conditional_term AND conditional_factor
conditional_factor ::= [ NOT ] conditional_primary
conditional_primary ::= simple_cond_expression | (conditional_expression)
simple_cond_expression ::=
comparison_expression |
between_expression |
in_expression |
like_expression |
null_comparison_expression |
empty_collection_comparison_expression |
collection_member_expression |
exists_expression
4.6.6 Operators and Operator Precedence
The operators are listed below in order of decreasing precedence.
• Navigation operator (.)
• Arithmetic operators:
+, - unary
JSR-338 Final Release
183
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final Release
Conditional Expressions
*, / multiplication and division
+, - addition and subtraction
• Comparison operators : =, >, >=, <, <=, <> (not equal), [NOT] BETWEEN, [NOT] LIKE,
[NOT] IN, IS [NOT] NULL, IS [NOT] EMPTY, [NOT] MEMBER [OF], [NOT] EXISTS
• Logical operators:
NOT
AND
OR
The following sections describe operators used in specific expressions.
4.6.7 Comparison Expressions
The syntax for the use of comparison expressions in a conditional expression is as follows[61]:
comparison_expression ::=
string_expression comparison_operator {string_expression | all_or_any_expression} |
boolean_expression { =|<> } {boolean_expression | all_or_any_expression} |
enum_expression { =|<>} {enum_expression | all_or_any_expression} |
datetime_expression comparison_operator
{datetime_expression | all_or_any_expression} |
entity_expression { = | <>} {entity_expression | all_or_any_expression} |
arithmetic_expression comparison_operator
{arithmetic_expression | all_or_any_expression} |
entity_type_expression { = | <>} entity_type_expression}
comparison_operator ::= = | > | >= | < | <= | <>
Examples:
item.cost * 1.08 <= 100.00
CONCAT(person.lastName, ‘, ’, person.firstName)) = ‘Jones, Sam’
TYPE(e) = ExemptEmployee
4.6.8 Between Expressions
The syntax for the use of the comparison operator [NOT] BETWEEN in a conditional expression is as
follows:
[61] Note that queries that contain subqueries on both sides of a comparison operation will not be portable across all databases.
4/2/13
184
JSR-338 Final Release
Oracle
Conditional Expressions
Java Persistence 2.1, Final Release
Query Language
between_expression ::=
arithmetic_expression [NOT] BETWEEN arithmetic_expression AND arithmetic_expression |
string_expression [NOT] BETWEEN string_expression AND string_expression |
datetime_expression [NOT] BETWEEN datetime_expression AND datetime_expression
The BETWEEN expression
x BETWEEN y AND z
is semantically equivalent to:
y <= x AND x <= z
The rules for unknown and NULL values in comparison operations apply. See Section 4.11.
Examples:
p.age BETWEEN 15 and 19 is equivalent to p.age >= 15 AND p.age <= 19
p.age NOT BETWEEN 15 and 19 is equivalent to p.age < 15 OR p.age > 19
In the following example, transactionHistory is a list of credit card transactions defined using
an order column.
SELECT t
FROM CreditCard c JOIN c.transactionHistory t
WHERE c.holder.name = ‘John Doe’ AND INDEX(t) BETWEEN 0 AND 9
4.6.9 In Expressions
The syntax for the use of the comparison operator [NOT] IN in a conditional expression is as follows:
in_expression ::=
{state_valued_path_expression | type_discriminator} [NOT] IN
{ ( in_item {, in_item}* ) | (subquery) | collection_valued_input_parameter }
in_item ::= literal | single_valued_input_parameter
The state_valued_path_expression must have a string, numeric, date, time, timestamp, or enum
value.
The literal and/or input parameter values must be like the same abstract schema type of the
state_valued_path_expression in type. (See Section 4.12).
The results of the subquery must be like the same abstract schema
state_valued_path_expression in type. Subqueries are discussed in Section 4.6.16.
JSR-338 Final Release
185
type
of
the
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final Release
Conditional Expressions
Examples:
o.country IN (’UK’, ’US’, ’France’) is true for UK and false for Peru, and is equivalent
to the expression (o.country = ’UK’) OR (o.country = ’US’) OR (o.country = ’
France’).
o.country NOT IN (’UK’, ’US’, ’France’) is false for UK and true for Peru, and is
equivalent to the expression NOT ((o.country = ’UK’) OR (o.country = ’US’) OR
(o.country = ’France’)).
There must be at least one element in the comma separated list that defines the set of values for the IN
expression.
If the value of a state_valued_path_expression or in_item in an IN or NOT IN expression is NULL
or unknown, the value of the expression is unknown.
Note that use of a collection-valued input parameter will mean that a static query cannot be precompiled.
4.6.10 Like Expressions
The syntax for the use of the comparison operator [NOT] LIKE in a conditional expression is as follows:
like_expression ::=
string_expression [NOT] LIKE pattern_value [ESCAPE escape_character]
The string_expression must have a string value. The pattern_value is a string literal or a string-valued input parameter in which an underscore (_) stands for any single character, a percent (%) character
stands for any sequence of characters (including the empty sequence), and all other characters stand for
themselves. The optional escape_character is a single-character string literal or a character-valued
input parameter (i.e., char or Character) and is used to escape the special meaning of the underscore and percent characters in pattern_value.[62]
Examples:
• address.phone LIKE ‘12%3’ is true for ‘123’ ‘12993’ and false for ‘1234’
• asentence.word LIKE ‘l_se’ is true for ‘lose’ and false for ‘loose’
• aword.underscored LIKE ‘\_%’ ESCAPE ‘\’ is true for ‘_foo’ and false for ‘bar’
• address.phone NOT LIKE ‘12%3’ is false for ‘123’ and ‘12993’ and true for ‘1234’
[62] Refer to [4] for a more precise characterization of these rules.
4/2/13
186
JSR-338 Final Release
Oracle
Conditional Expressions
Java Persistence 2.1, Final Release
Query Language
If the value of the string_expression or pattern_value is NULL or unknown, the value of the LIKE
expression is unknown. If the escape_character is specified and is NULL, the value of the LIKE
expression is unknown.
4.6.11 Null Comparison Expressions
The syntax for the use of the comparison operator IS NULL in a conditional expression is as follows:
null_comparison_expression ::=
{single_valued_path_expression | input_parameter } IS [NOT] NULL
A null comparison expression tests whether or not the single-valued path expression or input parameter
is a NULL value.
Null comparisons over instances of embeddable class types are not supported. Support for comparisons
over embeddables may be added in a future release of this specification.
4.6.12 Empty Collection Comparison Expressions
The syntax for the use of the comparison
empty_collection_comparison_expression is as follows:
operator
IS
EMPTY
in
an
empty_collection_comparison_expression ::=
collection_valued_path_expression IS [NOT] EMPTY
This expression tests whether or not the collection designated by the collection-valued path expression
is empty (i.e, has no elements).
Example:
SELECT o
FROM Order o
WHERE o.lineItems IS EMPTY
If the value of the collection-valued path expression in an empty collection comparison expression is
unknown, the value of the empty comparison expression is unknown.
JSR-338 Final Release
187
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final Release
Conditional Expressions
4.6.13 Collection Member Expressions
The syntax for the use of the comparison
collection_member_expression is as follows:
operator
MEMBER
OF[63]
in
an
collection_member_expression ::=
entity_or_value_expression [NOT] MEMBER [OF] collection_valued_path_expression
entity_or_value_expression ::=
single_valued_object_path_expression |
state_valued_path_expression |
simple_entity_or_value_expression
simple_entity_or_value_expression ::=
identification_variable |
input_parameter |
literal
This expression tests whether the designated value is a member of the collection specified by the collection-valued path expression.
Expressions that evaluate to embeddable types are not supported in collection member expressions.
Support for use of embeddables in collection member expressions may be added in a future release of
this specification.
If the collection valued path expression designates an empty collection, the value of the MEMBER OF
expression is FALSE and the value of the NOT MEMBER OF expression is TRUE. Otherwise, if the
value of the collection_valued_path_expression or entity_or_value_expression in the collection
member expression is NULL or unknown, the value of the collection member expression is unknown.
Example:
SELECT p
FROM Person p
WHERE 'Joe' MEMBER OF p.nicknames
4.6.14 Exists Expressions
An EXISTS expression is a predicate that is true only if the result of the subquery consists of one or
more values and that is false otherwise.
The syntax of an exists expression is
exists_expression::= [NOT] EXISTS (subquery)
[63] The use of the reserved word OF is optional in this expression.
4/2/13
188
JSR-338 Final Release
Oracle
Conditional Expressions
Java Persistence 2.1, Final Release
Query Language
Example:
SELECT DISTINCT emp
FROM Employee emp
WHERE EXISTS (
SELECT spouseEmp
FROM Employee spouseEmp
WHERE spouseEmp = emp.spouse)
The result of this query consists of all employees whose spouses are also employees.
4.6.15 All or Any Expressions
An ALL conditional expression is a predicate over a subquery that is true if the comparison operation is
true for all values in the result of the subquery or the result of the subquery is empty. An ALL conditional expression is false if the result of the comparison is false for at least one value of the result of the
subquery, and is unknown if neither true nor false.
An ANY conditional expression is a predicate over a subquery that is true if the comparison operation is
true for some value in the result of the subquery. An ANY conditional expression is false if the result of
the subquery is empty or if the comparison operation is false for every value in the result of the subquery, and is unknown if neither true nor false. The keyword SOME is synonymous with ANY.
The comparison operators used with ALL or ANY conditional expressions are =, <, <=, >, >=, <>. The
result of the subquery must be like that of the other argument to the comparison operator in type. See
Section 4.12.
The syntax of an ALL or ANY expression is specified as follows:
all_or_any_expression ::= { ALL | ANY | SOME} (subquery)
Example:
SELECT emp
FROM Employee emp
WHERE emp.salary > ALL (
SELECT m.salary
FROM Manager m
WHERE m.department = emp.department)
The result of this query consists of all employees whose salaries exceed the salaries of all managers in
their department.
4.6.16 Subqueries
Subqueries may be used in the WHERE or HAVING clause.[64]
The syntax for subqueries is as follows:
[64] Subqueries are restricted to the WHERE and HAVING clauses in this release. Support for subqueries in the FROM clause will be
considered in a later release of this specification.
JSR-338 Final Release
189
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final Release
Conditional Expressions
subquery ::= simple_select_clause subquery_from_clause [where_clause]
[groupby_clause] [having_clause]
simple_select_clause ::= SELECT [DISTINCT] simple_select_expression
subquery_from_clause ::=
FROM subselect_identification_variable_declaration
{, subselect_identification_variable_declaration |
collection_member_declaration }*
subselect_identification_variable_declaration ::=
identification_variable_declaration |
derived_path_expression [AS] identification_variable {join}* |
derived_collection_member_declaration
simple_select_expression::=
single_valued_path_expression |
scalar_expression |
aggregate_expression |
identification_variable
derived_path_expression ::=
general_derived_path.single_valued_object_field |
general_derived_path.collection_valued_field
general_derived_path ::=
simple_derived_path |
treated_derived_path{.single_valued_object_field}*
simple_derived_path ::= superquery_identification_variable{.single_valued_object_field}*
treated_derived_path ::= TREAT(general_derived_path AS subtype)
derived_collection_member_declaration ::=
IN superquery_identification_variable.{single_valued_object_field.}*collection_valued_field
Examples:
SELECT DISTINCT emp
FROM Employee emp
WHERE EXISTS (
SELECT spouseEmp
FROM Employee spouseEmp
WHERE spouseEmp = emp.spouse)
Note that some contexts in which a subquery can be used require that the subquery be a scalar subquery
(i.e., produce a single result). This is illustrated in the following examples using numeric comparisons.
SELECT c
FROM Customer c
WHERE (SELECT AVG(o.price) FROM c.orders o) > 100
SELECT goodCustomer
FROM Customer goodCustomer
WHERE goodCustomer.balanceOwed < (
SELECT AVG(c.balanceOwed)/2.0 FROM Customer c)
4/2/13
190
JSR-338 Final Release
Oracle
Conditional Expressions
Java Persistence 2.1, Final Release
Query Language
4.6.17 Scalar Expressions
Numeric, string, datetime, case, and entity type expressions result in scalar values.
Scalar expressions may be used in the SELECT clause of a query as well as in the WHERE[65] and
HAVING clauses.
scalar_expression::=
arithmetic_expression |
string_expression |
enum_expression |
datetime_expression |
boolean_expression |
case_expression |
entity_type_expression
4.6.17.1 Arithmetic Expressions
The arithmetic operators are:
+, - unary
*, / multiplication and division
+, - addition and subtraction
Arithmetic operations use numeric promotion.
Arithmetic functions are described in section 4.6.17.2.2.
4.6.17.2 Built-in String, Arithmetic, and Datetime Functional Expressions
The Java Persistence query language includes the built-in functions described in subsections 4.6.17.2.1,
4.6.17.2.2, 4.6.17.2.3, which may be used in the SELECT, WHERE or HAVING clause of a query. The
invocation of predefined database functions and user-defined database functions is described in section
4.6.17.3.
If the value of any argument to a functional expression is null or unknown, the value of the functional
expression is unknown.
4.6.17.2.1 String Functions
functions_returning_strings ::=
CONCAT(string_expression, string_expression {, string_expression}* ) |
SUBSTRING(string_expression,
arithmetic_expression [, arithmetic_expression]) |
TRIM([[trim_specification] [trim_character] FROM] string_expression) |
LOWER(string_expression) |
[65] Note that expressions involving aggregate operators must not be used in the WHERE clause.
JSR-338 Final Release
191
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final Release
Conditional Expressions
UPPER(string_expression)
trim_specification ::= LEADING | TRAILING | BOTH
functions_returning_numerics::=
LENGTH(string_expression) |
LOCATE(string_expression, string_expression[, arithmetic_expression])
The CONCAT function returns a string that is a concatenation of its arguments.
The second and third arguments of the SUBSTRING function denote the starting position and length of
the substring to be returned. These arguments are integers. The third argument is optional. If it is not
specified, the substring from the start position to the end of the string is returned. The first position of a
string is denoted by 1. The SUBSTRING function returns a string.
The TRIM function trims the specified character from a string. If the character to be trimmed is not
specified, it will be assumed to be space (or blank). The optional trim_character is a single-character
string literal or a character-valued input parameter (i.e., char or Character)[66]. If a trim specification is not provided, it defaults to BOTH. The TRIM function returns the trimmed string.
The LOWER and UPPER functions convert a string to lower and upper case, respectively, with regard
to the locale of the database. They return a string.
The LOCATE function returns the position of a given string within a string, starting the search at a specified position. It returns the first position at which the string was found as an integer. The first argument
is the string to be located; the second argument is the string to be searched; the optional third argument
is an integer that represents the string position at which the search is started (by default, the beginning of
the string to be searched). The first position in a string is denoted by 1. If the string is not found, 0 is
returned.[67]
The LENGTH function returns the length of the string in characters as an integer.
4.6.17.2.2 Arithmetic Functions
functions_returning_numerics::=
ABS(arithmetic_expression) |
SQRT(arithmetic_expression) |
MOD(arithmetic_expression, arithmetic_expression) |
SIZE(collection_valued_path_expression) |
INDEX(identification_variable)
The ABS function takes a numeric argument and returns a number (integer, float, or double) of the same
type as the argument to the function.
The SQRT function takes a numeric argument and returns a double.
[66] Note that not all databases support the use of a trim character other than the space character; use of this argument may result in
queries that are not portable.
[67] Note that not all databases support the use of the third argument to LOCATE; use of this argument may result in queries that are
not portable.
4/2/13
192
JSR-338 Final Release
Oracle
Conditional Expressions
Java Persistence 2.1, Final Release
Query Language
The MOD function takes two integer arguments and returns an integer.
Numeric arguments to these functions may correspond to the numeric Java object types as well as the
primitive numeric types.
The SIZE function returns an integer value, the number of elements of the collection. If the collection is
empty, the SIZE function evaluates to zero.
The INDEX function returns an integer value corresponding to the position of its argument in an
ordered list. The INDEX function can only be applied to identification variables denoting types for
which an order column has been specified.
In the following example, studentWaitlist is a list of students for which an order column has
been specified:
SELECT w.name
FROM Course c JOIN c.studentWaitlist w
WHERE c.name = ‘Calculus’
AND INDEX(w) = 0
4.6.17.2.3 Datetime Functions
functions_returning_datetime:=
CURRENT_DATE |
CURRENT_TIME |
CURRENT_TIMESTAMP
The datetime functions return the value of current date, time, and timestamp on the database server.
4.6.17.3 Invocation of Predefined and User-defined Database Functions
The invocation of functions other than the built-in functions of the Java Persistence query language is
supported by means of the function_invocation syntax. This includes the invocation of predefined database functions and user-defined database functions.
function_invocation::= FUNCTION(function_name {, function_arg}*)
function_arg ::=
literal |
state_valued_path_expression |
input_parameter |
scalar_expression
The function_name argument is a string that denotes the database function that is to be invoked. The
arguments must be suitable for the database function that is to be invoked. The result of the function
must be suitable for the invocation context.
The function may be a database-defined function or a user-defined function. The function may be a scalar function or an aggregate function.
JSR-338 Final Release
193
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final Release
Conditional Expressions
Applications that use the function_invocation syntax will not be portable across databases.
Example:
SELECT c
FROM Customer c
WHERE FUNCTION(‘hasGoodCredit’, c.balance, c.creditLimit)
4.6.17.4 Case Expressions
The following forms of case expressions are supported: general case expressions, simple case expressions, coalesce expressions, and nullif expressions.[68]
case_expression::=
general_case_expression |
simple_case_expression |
coalesce_expression |
nullif_expression
general_case_expression::=
CASE when_clause {when_clause}* ELSE scalar_expression END
when_clause::= WHEN conditional_expression THEN scalar_expression
simple_case_expression::=
CASE case_operand simple_when_clause {simple_when_clause}*
ELSE scalar_expression
END
case_operand::= state_valued_path_expression | type_discriminator
simple_when_clause::= WHEN scalar_expression THEN scalar_expression
coalesce_expression::= COALESCE(scalar_expression {, scalar_expression}+)
nullif_expression::= NULLIF(scalar_expression, scalar_expression)
Examples:
UPDATE Employee e
SET e.salary =
CASE WHEN e.rating = 1 THEN e.salary * 1.1
WHEN e.rating = 2 THEN e.salary * 1.05
ELSE e.salary * 1.01
END
UPDATE Employee e
SET e.salary =
CASE e.rating WHEN 1 THEN e.salary * 1.1
WHEN 2 THEN e.salary * 1.05
ELSE e.salary * 1.01
END
[68] Note that not all databases support the use of SQL case expressions. The use of case expressions may result in queries that are not
portable to such databases.
4/2/13
194
JSR-338 Final Release
Oracle
Conditional Expressions
Java Persistence 2.1, Final Release
Query Language
SELECT e.name,
CASE TYPE(e) WHEN Exempt THEN 'Exempt'
WHEN Contractor THEN 'Contractor'
WHEN Intern THEN 'Intern'
ELSE 'NonExempt'
END
FROM Employee e
WHERE e.dept.name = 'Engineering'
SELECT e.name,
f.name,
CONCAT(CASE WHEN f.annualMiles > 50000 THEN 'Platinum '
WHEN f.annualMiles > 25000 THEN 'Gold '
ELSE ''
END,
'Frequent Flyer')
FROM Employee e JOIN e.frequentFlierPlan f
4.6.17.5 Entity Type Expressions
An entity type expression can be used to restrict query polymorphism. The TYPE operator returns the
exact type of the argument.
The syntax of an entity type expression is as follows:
entity_type_expression ::=
type_discriminator |
entity_type_literal |
input_parameter
type_discriminator ::=
TYPE(general_identification_variable |
single_valued_object_path_expression |
input_parameter )
An entity_type_literal is designated by the entity name.
The Java class of the entity is used as an input parameter to specify the entity type.
Examples:
SELECT e
FROM Employee e
WHERE TYPE(e) IN (Exempt, Contractor)
SELECT e
FROM Employee e
WHERE TYPE(e) IN (:empType1, :empType2)
SELECT e
FROM Employee e
WHERE TYPE(e) IN :empTypes
SELECT TYPE(e)
FROM Employee e
WHERE TYPE(e) <> Exempt
JSR-338 Final Release
195
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final Release
GROUP BY, HAVING
4.7 GROUP BY, HAVING
The GROUP BY construct enables the aggregation of result values according to a set of properties. The
HAVING construct enables conditions to be specified that further restrict the query result. Such conditions are restrictions upon the groups.
The syntax of the GROUP BY and HAVING clauses is as follows:
groupby_clause ::= GROUP BY groupby_item {, groupby_item}*
groupby_item ::= single_valued_path_expression | identification_variable
having_clause ::= HAVING conditional_expression
If a query contains both a WHERE clause and a GROUP BY clause, the effect is that of first applying
the where clause, and then forming the groups and filtering them according to the HAVING clause. The
HAVING clause causes those groups to be retained that satisfy the condition of the HAVING clause.
The requirements for the SELECT clause when GROUP BY is used follow those of SQL: namely, any
item that appears in the SELECT clause (other than as an aggregate function or as an argument to an
aggregate function) must also appear in the GROUP BY clause. In forming the groups, null values are
treated as the same for grouping purposes.
Grouping by an entity is permitted. In this case, the entity must contain no serialized state fields or
lob-valued state fields that are eagerly fetched. Grouping by an entity that contains serialized state fields
or lob-valued state fields is not portable, since the implementation is permitted to eagerly fetch fields or
properties that have been specified as LAZY.
Grouping by embeddables is not supported.
The HAVING clause is used to filter over the groups, and can contain aggregate functions over
attributes included in the groups and/or functions or other query language operators over the attributes
that are used for grouping. It is not required that an aggregate function used in the HAVING clause also
be used in the SELECT clause.
If there is no GROUP BY clause and the HAVING clause is used, the result is treated as a single group,
and the select list can only consist of aggregate functions. The use of HAVING in the absence of
GROUP BY is not required to be supported by an implementation of this specification. Portable applications should not rely on HAVING without the use of GROUP BY.
4/2/13
196
JSR-338 Final Release
Oracle
SELECT Clause
Java Persistence 2.1, Final Release
Query Language
Examples:
SELECT c.status, AVG(c.filledOrderCount), COUNT(c)
FROM Customer c
GROUP BY c.status
HAVING c.status IN (1, 2)
SELECT c.country, COUNT(c)
FROM Customer c
GROUP BY c.country
HAVING COUNT(c) > 30
SELECT c, COUNT(o)
FROM Customer c JOIN c.orders o
GROUP BY c
HAVING COUNT(o) >= 5
4.8 SELECT Clause
The SELECT clause denotes the query result. More than one value may be returned from the SELECT
clause of a query.
The SELECT clause can contain one or more of the following elements: an identification variable that
ranges over an abstract schema type, a single-valued path expression, a scalar expression, an aggregate
expression, a constructor expression.
The SELECT clause has the following syntax:
select_clause ::= SELECT [DISTINCT] select_item {, select_item}*
select_item ::= select_expression [ [AS] result_variable]
select_expression ::=
single_valued_path_expression |
scalar_expression |
aggregate_expression |
identification_variable |
OBJECT(identification_variable) |
constructor_expression
constructor_expression ::=
NEW constructor_name ( constructor_item {, constructor_item}* )
constructor_item ::=
single_valued_path_expression |
scalar_expression |
aggregate_expression |
identification_variable
aggregate_expression ::=
{ AVG | MAX | MIN | SUM } ([DISTINCT] state_valued_path_expression) |
COUNT ([DISTINCT] identification_variable | state_valued_path_expression |
single_valued_object_path_expression) |
function_invocation
JSR-338 Final Release
197
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final Release
SELECT Clause
For example:
SELECT c.id, c.status
FROM Customer c JOIN c.orders o
WHERE o.count > 100
In the following example, videoInventory is a Map from the entity Movie to the number of copies
in stock:
SELECT v.location.street, KEY(i).title, VALUE(i)
FROM VideoStore v JOIN v.videoInventory i
WHERE v.location.zipcode = '94301' AND VALUE(i) > 0
Note that the SELECT clause must be specified to return only single-valued expressions. The query
below is therefore not valid:
SELECT o.lineItems FROM Order AS o
The DISTINCT keyword is used to specify that duplicate values must be eliminated from the query
result.
If DISTINCT is not specified, duplicate values are not eliminated.
The result of DISTINCT over embeddable objects or map entry results is undefined.
Standalone identification variables in the SELECT clause may optionally be qualified by the OBJECT
operator.[69] The SELECT clause must not use the OBJECT operator to qualify path expressions.
A result_variable may be used to name a select_item in the query result.[70]
For example,
SELECT c, COUNT(l) AS itemCount
FROM Customer c JOIN c.Orders o JOIN o.lineItems l
WHERE c.address.state = ‘CA’
GROUP BY c
ORDER BY itemCount
4.8.1 Result Type of the SELECT Clause
The type of the query result specified by the SELECT clause of a query is an entity abstract schema
type, a state field type, the result of a scalar expression, the result of an aggregate function, the result of
a construction operation, or some sequence of these.
[69] Note that the keyword OBJECT is not required. It is preferred that it be omitted for new queries.
[70] This can be used, for example, to refer to a select expression in the ORDER BY clause.
4/2/13
198
JSR-338 Final Release
Oracle
SELECT Clause
Java Persistence 2.1, Final Release
Query Language
The result type of the SELECT clause is defined by the the result types of the select expressions contained in it. When multiple select expressions are used in the SELECT clause, the elements in this result
correspond in order to the order of their specification in the SELECT clause and in type to the result
types of each of the select expressions.
The type of the result of a select_expression is as follows:
• The result type of an identification_variable is the type of the entity object or embeddable
object to which the identification variable corresponds. The type of an identification_variable
that refers to an entity abstract schema type is the type of the entity to which that identification
variable corresponds or a subtype as determined by the object/relational mapping.
• The
result
type
of
a
single_valued_path_expression
that
is
a
state_field_path_expression is the same type as the corresponding state field of the entity or
embeddable class. If the state field of the entity is a primitive type, the result type is the corresponding object type.
• The
result
type
of
a
single_valued_path_expression
that
is
a
single_valued_object_path_expression is the type of the entity object or embeddable
object to which the path expression corresponds. A single_valued_object_path_expression
that results in an entity object will result in an entity of the type of the relationship field or the
subtype of the relationship field of the entity object as determined by the object/relational mapping.
• The result type of a single_valued_path_expression that is an identification_variable to
which the KEY or VALUE function has been applied is determined by the type of the map key
or value respectively, as defined by the above rules.
• The result type of a single_valued_path_expression that is an identification_variable to
which the ENTRY function has been applied is java.util.Map.Entry, where the key
and value types of the map entry are determined by the above rules as applied to the map key
and map value respectively.
• The result type of a scalar_expression is the type of the scalar value to which the expression
evaluates. The result type of a numeric scalar_expression is defined in section 4.8.6.
• The result type of an entity_type_expression scalar expression is the Java class to which the
resulting abstract schema type corresponds.
• The result type of aggregate_expression is defined in section 4.8.5.
• The result type of a constructor_expression is the type of the class for which the constructor
is defined. The types of the arguments to the constructor are defined by the above rules.
4.8.2 Constructor Expressions in the SELECT Clause
A constructor may be used in the SELECT list to return an instance of a Java class. The specified class
is not required to be an entity or to be mapped to the database. The constructor name must be fully qualified.
JSR-338 Final Release
199
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final Release
SELECT Clause
If an entity class name is specified as the constructor name in the SELECT NEW clause, the resulting
entity instances will be in either the new or the detached state, depending on whether a primary key is
retrieved for the constructed object.
If a single_valued_path_expression or identification_variable that is an argument to the constructor
references an entity, the resulting entity instance referenced by that single_valued_path_expression
or identification_variable will be in the managed state.
For example,
SELECT NEW com.acme.example.CustomerDetails(c.id, c.status, o.count)
FROM Customer c JOIN c.orders o
WHERE o.count > 100
4.8.3 Null Values in the Query Result
If the result of a query corresponds to an association field or state field whose value is null, that null
value is returned in the result of the query method. The IS NOT NULL construct can be used to eliminate such null values from the result set of the query.
Note, however, that state field types defined in terms of Java numeric primitive types cannot produce
NULL values in the query result. A query that returns such a state field type as a result type must not
return a null value.
4.8.4 Embeddables in the Query Result
If the result of a query corresponds to an identification variable or state field whose value is an
embeddable, the embeddable instance returned by the query will not be in the managed state (i.e., it will
not be part of the state of any managed entity).
In the following example, the Address instances returned by the query will reference Phone
instances. While the Phone instances will be managed, the Address instances referenced by the
addr result variable will not be. Modifications to these embeddable instances will have no effect on
persistent state.
@Entity
public class Employee {
@Id int id;
Address address;
...
}
@Embeddable
public class Address {
String street;
...
@OneToOne Phone phone;
}
4/2/13
// fetch=EAGER
200
JSR-338 Final Release
Oracle
SELECT Clause
Java Persistence 2.1, Final Release
@Entity
public class Phone {
@Id int id;
...
@OneToOne(mappedBy="address.phone") Employee emp;
}
Query Language
// fetch=EAGER
SELECT e.address AS addr
FROM Employee e
4.8.5 Aggregate Functions in the SELECT Clause
The result of a query may be the result of an aggregate function applied to a path expression.
The following aggregate functions can be used in the SELECT clause of a query: AVG, COUNT, MAX,
MIN, SUM, aggregate functions defined in the database.
For all aggregate functions except COUNT, the path expression that is the argument to the aggregate
function must terminate in a state field. The path expression argument to COUNT may terminate in
either a state field or a association field, or the argument to COUNT may be an identification variable.
Arguments to the functions SUM and AVG must be numeric. Arguments to the functions MAX and
MIN must correspond to orderable state field types (i.e., numeric types, string types, character types, or
date types).
The Java type that is contained in the result of a query using an aggregate function is as follows:
• COUNT returns Long.
• MAX, MIN return the type of the state field to which they are applied.
• AVG returns Double.
• SUM returns Long when applied to state fields of integral types (other than BigInteger); Double when applied to state fields of floating point types; BigInteger when applied to state fields
of type BigInteger; and BigDecimal when applied to state fields of type BigDecimal.
Null values are eliminated before the aggregate function is applied, regardless of whether the keyword
DISTINCT is specified.
If SUM, AVG, MAX, or MIN is used, and there are no values to which the aggregate function can be
applied, the result of the aggregate function is NULL.
If COUNT is used, and there are no values to which COUNT can be applied, the result of the aggregate
function is 0.
The argument to an aggregate function may be preceded by the keyword DISTINCT to specify that
duplicate values are to be eliminated before the aggregate function is applied.[71]
JSR-338 Final Release
201
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final Release
SELECT Clause
The use of DISTINCT with COUNT is not supported for arguments of embeddable types or map entry
types.
The invocation of aggregate database functions, including user defined functions, is supported by means
of the FUNCTION operator. See section 4.6.17.3.
4.8.5.1 Examples
The following query returns the average order quantity:
SELECT AVG(o.quantity) FROM Order o
The following query returns the total cost of the items that John Smith has ordered.
SELECT SUM(l.price)
FROM Order o JOIN o.lineItems l JOIN o.customer c
WHERE c.lastname = ‘Smith’ AND c.firstname = ‘John’
The following query returns the total number of orders.
SELECT COUNT(o)
FROM Order o
The following query counts the number of items in John Smith’s order for which prices have been specified.
SELECT COUNT(l.price)
FROM Order o JOIN o.lineItems l JOIN o.customer c
WHERE c.lastname = ‘Smith’ AND c.firstname = ‘John’
Note that this is equivalent to:
SELECT COUNT(l)
FROM Order o JOIN o.lineItems l JOIN o.customer c
WHERE c.lastname = ‘Smith’ AND c.firstname = ‘John’
AND l.price IS NOT NULL
4.8.6 Numeric Expressions in the SELECT Clause
The type of a numeric expression in the query result is determined as follows:
An operand that corresponds to a persistent state field is of the same type as that persistent state field.
An operand that corresponds to one of arithmetic functions described in section 4.6.17.2.2 is of the type
defined by section 4.6.17.2.2.
An operand that corresponds to one of an aggregate functions described in section 4.8.5 is of the type
defined by section 4.8.5.
[71] It is legal to specify DISTINCT with MAX or MIN, but it does not affect the result.
4/2/13
202
JSR-338 Final Release
Oracle
ORDER BY Clause
Java Persistence 2.1, Final Release
Query Language
The result of a case expression, coalesce expression, nullif expression, or arithmetic expression (+, -, *,
/) is determined by applying the following rule to its operands[72].
• If there is an operand of type Double or double, the result of the operation is of type Double;
• otherwise, if there is an operand of type Float or float, the result of the operation is of type
Float;
• otherwise, if there is an operand of type BigDecimal, the result of the operation is of type BigDecimal;
• otherwise, if there is an operand of type BigInteger, the result of the operation is of type BigInteger, unless the operator is / (division), in which case the numeric result type is not further
defined;
• otherwise, if there is an operand of type Long or long, the result of the operation is of type
Long, unless the operator is / (division), in which case the numeric result type is not further
defined;
• otherwise, if there is an operand of integral type, the result of the operation is of type Integer,
unless the operator is / (division), in which case the numeric result type is not further defined.
Users should note that the semantics of the SQL division operation are not standard across
databases. In particular, when both operands are of integral types, the result of the division
operation will be an integral type in some databases, and an non-integral type in others. Portable applications should not assume a particular result type.
4.9 ORDER BY Clause
The ORDER BY clause allows the objects or values that are returned by the query to be ordered.
The syntax of the ORDER BY clause is
orderby_clause ::= ORDER BY orderby_item {, orderby_item}*
orderby_item ::=
{ state_field_path_expression | general_identification_variable | result_variable }
[ASC | DESC]
An orderby_item must be one of the following:
1.
A state_field_path_expression that evaluates to an orderable state field of an entity or
embeddable class abstract schema type designated in the SELECT clause by one of the following:
• a general_identification_variable
• a single_valued_object_path_expression
[72] In the case of a general or simple case expression, these are the scalar expressions of the THEN and ELSE clauses.
JSR-338 Final Release
203
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final Release
ORDER BY Clause
2.
A state_field_path_expression that evaluates to the same state field of the same entity or
embeddable abstract schema type as a state_field_path_expression in the SELECT clause
3.
A general_identification_variable that evaluates to the same map field of the same entity or
embeddable abstract schema type as a general_identification_variable in the SELECT
clause
4.
A result_variable that refers to an orderable item in the SELECT clause for which the same
result_variable has been specified. This may be the result of an aggregate_expression, a
scalar_expression, or a state_field_path_expression in the SELECT clause.
For example, the four queries below are legal.
SELECT o
FROM Customer c JOIN c.orders o JOIN c.address a
WHERE a.state = ‘CA’
ORDER BY o.quantity DESC, o.totalcost
SELECT o.quantity, a.zipcode
FROM Customer c JOIN c.orders o JOIN c.address a
WHERE a.state = ‘CA’
ORDER BY o.quantity, a.zipcode
SELECT o.quantity, o.cost*1.08 AS taxedCost, a.zipcode
FROM Customer c JOIN c.orders o JOIN c.address a
WHERE a.state = ‘CA’ AND a.county = ‘Santa Clara’
ORDER BY o.quantity, taxedCost, a.zipcode
SELECT AVG(o.quantity) as q, a.zipcode
FROM Customer c JOIN c.orders o JOIN c.address a
WHERE a.state = ‘CA’
GROUP BY a.zipcode
ORDER BY q DESC
The following two queries are not legal because the orderby_item is not reflected in the SELECT
clause of the query.
SELECT p.product_name
FROM Order o JOIN o.lineItems l JOIN l.product p JOIN o.customer c
WHERE c.lastname = ‘Smith’ AND c.firstname = ‘John’
ORDER BY p.price
SELECT p.product_name
FROM Order o, IN(o.lineItems) l JOIN o.customer c
WHERE c.lastname = ‘Smith’ AND c.firstname = ‘John’
ORDER BY o.quantity
If more than one orderby_item is specified, the left-to-right sequence of the orderby_item elements
determines the precedence, whereby the leftmost orderby_item has highest precedence.
The keyword ASC specifies that ascending ordering be used for the associated orderby_item; the keyword DESC specifies that descending ordering be used. Ascending ordering is the default.
4/2/13
204
JSR-338 Final Release
Oracle
Bulk Update and Delete Operations
Java Persistence 2.1, Final Release
Query Language
SQL rules for the ordering of null values apply: that is, all null values must appear before all non-null
values in the ordering or all null values must appear after all non-null values in the ordering, but it is not
specified which.
The ordering of the query result is preserved in the result of the query execution method if the ORDER
BY clause is used.
4.10 Bulk Update and Delete Operations
Bulk update and delete operations apply to entities of a single entity class (together with its subclasses,
if any). Only one entity abstract schema type may be specified in the FROM or UPDATE clause.
The syntax of these operations is as follows:
update_statement ::= update_clause [where_clause]
update_clause ::= UPDATE entity_name [[AS] identification_variable]
SET update_item {, update_item}*
update_item ::= [identification_variable.]{single_valued_embeddable_object_field.}*
{state_field | single_valued_object_field} = new_value
new_value ::=
scalar_expression |
simple_entity_expression |
NULL
delete_statement ::= delete_clause [where_clause]
delete_clause ::= DELETE FROM entity_name [[AS] identification_variable]
The syntax of the WHERE clause is described in Section 4.5.
A delete operation only applies to entities of the specified class and its subclasses. It does not cascade to
related entities.
The new_value specified for an update operation must be compatible in type with the field to which it
is assigned.
Bulk update maps directly to a database update operation, bypassing optimistic locking checks. Portable
applications must manually update the value of the version column, if desired, and/or manually validate
the value of the version column.
The persistence context is not synchronized with the result of the bulk update or delete.
Caution should be used when executing bulk update or delete operations because they may result in
inconsistencies between the database and the entities in the active persistence context. In general, bulk
update and delete operations should only be performed within a transaction in a new persistence context or before fetching or accessing entities whose state might be affected by such operations.
JSR-338 Final Release
205
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final Release
Null Values
Examples:
DELETE
FROM Customer c
WHERE c.status = ‘inactive’
DELETE
FROM Customer c
WHERE c.status = ‘inactive’
AND c.orders IS EMPTY
UPDATE Customer c
SET c.status = ‘outstanding’
WHERE c.balance < 10000
UPDATE Employee e
SET e.address.building = 22
WHERE e.address.building = 14
AND e.address.city = ‘Santa Clara’
AND e.project = ‘Java EE’
4.11 Null Values
When the target of a reference does not exist in the database, its value is regarded as NULL. SQL NULL
semantics [4] defines the evaluation of conditional expressions containing NULL values.
The following is a brief description of these semantics:
• Comparison or arithmetic operations with a NULL value always yield an unknown value.
• Two NULL values are not considered to be equal, the comparison yields an unknown value.
• Comparison or arithmetic operations with an unknown value always yield an unknown value.
• The IS NULL and IS NOT NULL operators convert a NULL state field or single-valued object
field value into the respective TRUE or FALSE value.
• Boolean operators use three valued logic, defined by Table 1, Table 2, and Table 3.
Table 1
Definition of the AND Operator
AND
4/2/13
T
F
U
T
T
F
U
F
F
F
F
U
U
F
U
206
JSR-338 Final Release
Oracle
Equality and Comparison Semantics
Table 2
Table 3
Java Persistence 2.1, Final Release
Query Language
Definition of the OR Operator
OR
T
F
U
T
T
T
T
F
T
F
U
U
T
U
U
Definition of the NOT Operator
NOT
T
F
F
T
U
U
Note: The Java Persistence query language defines the empty string, ‘’, as a string with 0 length, which
is not equal to a NULL value. However, NULL values and empty strings may not always be distinguished when queries are mapped to some databases. Application developers should therefore not rely
on the semantics of query comparisons involving the empty string and NULL value.
4.12 Equality and Comparison Semantics
Only the values of like types are permitted to be compared. A type is like another type if they correspond to the same Java language type, or if one is a primitive Java language type and the other is the
wrappered Java class type equivalent (e.g., int and Integer are like types in this sense). There is one
exception to this rule: it is valid to compare numeric values for which the rules of numeric promotion
apply. Conditional expressions attempting to compare non-like type values are disallowed except for
this numeric case.
Note that the arithmetic operators and comparison operators are permitted to be applied to
state fields and input parameters of the wrappered Java class equivalents to the primitive
numeric Java types.
Two entities of the same abstract schema type are equal if and only if they have the same primary key
value.
Only equality/inequality comparisons over enums are required to be supported.
Comparisons over instances of embeddable class or map entry types are not supported.
JSR-338 Final Release
207
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final Release
Examples
4.13 Examples
The following examples illustrate the syntax and semantics of the Java Persistence query language.
These examples are based on the example presented in Section 4.3.2.
4.13.1 Simple Queries
Find all orders:
SELECT o
FROM Order o
Find all orders that need to be shipped to California:
SELECT o
FROM Order o
WHERE o.shippingAddress.state = ‘CA’
Find all states for which there are orders:
SELECT DISTINCT o.shippingAddress.state
FROM Order o
4.13.2 Queries with Relationships
Find all orders that have line items:
SELECT DISTINCT o
FROM Order o JOIN o.lineItems l
Note that the result of this query does not include orders with no associated line items. This query can
also be written as:
SELECT o
FROM Order o
WHERE o.lineItems IS NOT EMPTY
Find all orders that have no line items:
SELECT o
FROM Order o
WHERE o.lineItems IS EMPTY
Find all pending orders:
SELECT DISTINCT o
FROM Order o JOIN o.lineItems l
WHERE l.shipped = FALSE
4/2/13
208
JSR-338 Final Release
Oracle
Examples
Java Persistence 2.1, Final Release
Query Language
Find all orders in which the shipping address differs from the billing address. This example assumes
that the application developer uses two distinct entity types to designate shipping and billing addresses.
SELECT o
FROM Order o
WHERE
NOT (o.shippingAddress.state = o.billingAddress.state AND
o.shippingAddress.city = o.billingAddress.city AND
o.shippingAddress.street = o.billingAddress.street)
If the application developer uses a single entity type in two different relationships for both the shipping
address and the billing address, the above expression can be simplified based on the equality rules
defined in Section 4.12. The query can then be written as:
SELECT o
FROM Order o
WHERE o.shippingAddress <> o.billingAddress
The query checks whether the same entity abstract schema type instance (identified by its primary key)
is related to an order through two distinct relationships.
4.13.3 Queries Using Input Parameters
The following query finds the orders for a product whose name is designated by an input parameter:
SELECT DISTINCT o
FROM Order o JOIN o.lineItems l
WHERE l.product.name = ?1
For this query, the input parameter must be of the type of the state field name, i.e., a string.
JSR-338 Final Release
209
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final Release
BNF
4.14 BNF
BNF notation summary:
• { ... } grouping
• [ ... ] optional constructs
• boldface keywords
• * zero or more
• + one or more
• | alternates
The following is the BNF for the Java Persistence query language.
QL_statement ::= select_statement | update_statement | delete_statement
select_statement ::= select_clause from_clause [where_clause] [groupby_clause]
[having_clause] [orderby_clause]
update_statement ::= update_clause [where_clause]
delete_statement ::= delete_clause [where_clause]
from_clause ::=
FROM identification_variable_declaration
{, {identification_variable_declaration | collection_member_declaration}}*
identification_variable_declaration ::= range_variable_declaration { join | fetch_join }*
range_variable_declaration ::= entity_name [AS] identification_variable
join ::= join_spec join_association_path_expression [AS] identification_variable
[join_condition]
fetch_join ::= join_spec FETCH join_association_path_expression
join_spec::= [ LEFT [OUTER] | INNER ] JOIN
join_condition ::= ON conditional_expression
join_association_path_expression ::=
join_collection_valued_path_expression |
join_single_valued_path_expression |
TREAT(join_collection_valued_path_expression AS subtype) |
TREAT(join_single_valued_path_expression AS subtype)
join_collection_valued_path_expression::=
identification_variable.{single_valued_embeddable_object_field.}*collection_valued_field
join_single_valued_path_expression::=
identification_variable.{single_valued_embeddable_object_field.}*single_valued_object_field
collection_member_declaration ::=
IN (collection_valued_path_expression) [AS] identification_variable
qualified_identification_variable :: =
map_field_identification_variable |
ENTRY(identification_variable)
map_field_identification_variable :: =
KEY(identification_variable) |
4/2/13
210
JSR-338 Final Release
Oracle
BNF
Java Persistence 2.1, Final Release
Query Language
VALUE(identification_variable)
single_valued_path_expression ::=
qualified_identification_variable |
TREAT(qualified_identification_variable AS subtype) |
state_field_path_expression |
single_valued_object_path_expression
general_identification_variable ::=
identification_variable |
map_field_identification_variable
general_subpath ::= simple_subpath | treated_subpath{.single_valued_object_field}*
simple_subpath ::=
general_identification_variable |
general_identification_variable{.single_valued_object_field}*
treated_subpath ::= TREAT(general_subpath AS subtype)
state_field_path_expression ::= general_subpath.state_field
state_valued_path_expression ::=
state_field_path_expression | general_identification_variable
single_valued_object_path_expression ::= general_subpath.single_valued_object_field
collection_valued_path_expression ::= general_subpath.{collection_valued_field
update_clause ::= UPDATE entity_name [[AS] identification_variable]
SET update_item {, update_item}*
update_item ::= [identification_variable.]{single_valued_embeddable_object_field.}*
{state_field | single_valued_object_field} = new_value
new_value ::=
scalar_expression |
simple_entity_expression |
NULL
delete_clause ::= DELETE FROM entity_name [[AS] identification_variable]
select_clause ::= SELECT [DISTINCT] select_item {, select_item}*
select_item ::= select_expression [[AS] result_variable]
select_expression ::=
single_valued_path_expression |
scalar_expression |
aggregate_expression |
identification_variable |
OBJECT(identification_variable) |
constructor_expression
constructor_expression ::=
NEW constructor_name ( constructor_item {, constructor_item}* )
constructor_item ::=
single_valued_path_expression |
scalar_expression |
aggregate_expression |
identification_variable
aggregate_expression ::=
{ AVG | MAX | MIN | SUM } ([DISTINCT] state_valued_path_expression) |
COUNT ([DISTINCT] identification_variable | state_valued_path_expression |
single_valued_object_path_expression) |
function_invocation
JSR-338 Final Release
211
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final Release
BNF
where_clause ::= WHERE conditional_expression
groupby_clause ::= GROUP BY groupby_item {, groupby_item}*
groupby_item ::= single_valued_path_expression | identification_variable
having_clause ::= HAVING conditional_expression
orderby_clause ::= ORDER BY orderby_item {, orderby_item}*
orderby_item ::=
state_field_path_expression | general_identification_variable | result_variable
[ ASC | DESC ]
subquery ::= simple_select_clause subquery_from_clause [where_clause]
[groupby_clause] [having_clause]
subquery_from_clause ::=
FROM subselect_identification_variable_declaration
{, subselect_identification_variable_declaration |
collection_member_declaration}*
subselect_identification_variable_declaration ::=
identification_variable_declaration |
derived_path_expression [AS] identification_variable {join}*|
derived_collection_member_declaration
derived_path_expression ::=
general_derived_path.single_valued_object_field |
general_derived_path.collection_valued_field
general_derived_path ::=
simple_derived_path |
treated_derived_path{.single_valued_object_field}*
simple_derived_path ::= superquery_identification_variable{.single_valued_object_field}*
treated_derived_path ::= TREAT(general_derived_path AS subtype)
derived_collection_member_declaration ::=
IN superquery_identification_variable.{single_valued_object_field.}*collection_valued_field
simple_select_clause ::= SELECT [DISTINCT] simple_select_expression
simple_select_expression::=
single_valued_path_expression |
scalar_expression |
aggregate_expression |
identification_variable
scalar_expression ::=
arithmetic_expression |
string_expression |
enum_expression |
datetime_expression |
boolean_expression |
case_expression |
entity_type_expression
conditional_expression ::= conditional_term | conditional_expression OR conditional_term
conditional_term ::= conditional_factor | conditional_term AND conditional_factor
conditional_factor ::= [ NOT ] conditional_primary
conditional_primary ::= simple_cond_expression | (conditional_expression)
simple_cond_expression ::=
comparison_expression |
between_expression |
in_expression |
4/2/13
212
JSR-338 Final Release
Oracle
BNF
Java Persistence 2.1, Final Release
Query Language
like_expression |
null_comparison_expression |
empty_collection_comparison_expression |
collection_member_expression |
exists_expression
between_expression ::=
arithmetic_expression [NOT] BETWEEN
arithmetic_expression AND arithmetic_expression |
string_expression [NOT] BETWEEN string_expression AND string_expression |
datetime_expression [NOT] BETWEEN
datetime_expression AND datetime_expression
in_expression ::=
{state_valued_path_expression | type_discriminator} [NOT] IN
{ ( in_item {, in_item}* ) | (subquery) | collection_valued_input_parameter }
in_item ::= literal | single_valued_input_parameter
like_expression ::=
string_expression [NOT] LIKE pattern_value [ESCAPE escape_character]
null_comparison_expression ::=
{single_valued_path_expression | input_parameter} IS [NOT] NULL
empty_collection_comparison_expression ::=
collection_valued_path_expression IS [NOT] EMPTY
collection_member_expression ::= entity_or_value_expression
[NOT] MEMBER [OF] collection_valued_path_expression
entity_or_value_expression ::=
single_valued_object_path_expression |
state_field_path_expression |
simple_entity_or_value_expression
simple_entity_or_value_expression ::=
identification_variable |
input_parameter |
literal
exists_expression::= [NOT] EXISTS (subquery)
all_or_any_expression ::= { ALL | ANY | SOME} (subquery)
comparison_expression ::=
string_expression comparison_operator {string_expression | all_or_any_expression} |
boolean_expression { =|<>} {boolean_expression | all_or_any_expression} |
enum_expression { =|<>} {enum_expression | all_or_any_expression} |
datetime_expression comparison_operator
{datetime_expression | all_or_any_expression} |
entity_expression { = | <>} {entity_expression | all_or_any_expression} |
arithmetic_expression comparison_operator
{arithmetic_expression | all_or_any_expression} |
entity_type_expression { =|<>} entity_type_expression}
comparison_operator ::= = | > | >= | < | <= | <>
arithmetic_expression ::=
arithmetic_term | arithmetic_expression { + | - } arithmetic_term
arithmetic_term ::= arithmetic_factor | arithmetic_term { * | / } arithmetic_factor
arithmetic_factor ::= [{ + | - }] arithmetic_primary
JSR-338 Final Release
213
4/2/13
Oracle
Query Language
Java Persistence 2.1, Final Release
BNF
arithmetic_primary ::=
state_valued_path_expression |
numeric_literal |
(arithmetic_expression) |
input_parameter |
functions_returning_numerics |
aggregate_expression |
case_expression |
function_invocation |
(subquery)
string_expression ::=
state_valued_path_expression |
string_literal |
input_parameter |
functions_returning_strings |
aggregate_expression |
case_expression |
function_invocation |
(subquery)
datetime_expression ::=
state_valued_path_expression |
input_parameter |
functions_returning_datetime |
aggregate_expression |
case_expression |
function_invocation |
date_time_timestamp_literal |
(subquery)
boolean_expression ::=
state_valued_path_expression |
boolean_literal |
input_parameter |
case_expression |
function_invocation |
(subquery)
enum_expression ::=
state_valued_path_expression |
enum_literal |
input_parameter |
case_expression |
(subquery)
entity_expression ::=
single_valued_object_path_expression | simple_entity_expression
simple_entity_expression ::=
identification_variable |
input_parameter
entity_type_expression ::=
type_discriminator |
entity_type_literal |
input_parameter
4/2/13
214
JSR-338 Final Release
Oracle
BNF
Java Persistence 2.1, Final Release
Query Language
type_discriminator ::=
TYPE(general_identification_variable |
single_valued_object_path_expression |
input_parameter)
functions_returning_numerics::=
LENGTH(string_expression) |
LOCATE(string_expression, string_expression[, arithmetic_expression]) |
ABS(arithmetic_expression) |
SQRT(arithmetic_expression) |
MOD(arithmetic_expression, arithmetic_expression) |
SIZE(collection_valued_path_expression) |
INDEX(identification_variable)
functions_returning_datetime ::=
CURRENT_DATE |
CURRENT_TIME |
CURRENT_TIMESTAMP
functions_returning_strings ::=
CONCAT(string_expression, string_expression {, string_expression}*) |
SUBSTRING(string_expression, arithmetic_expression [, arithmetic_expression]) |
TRIM([[trim_specification] [trim_character] FROM] string_expression) |
LOWER(string_expression) |
UPPER(string_expression)
trim_specification ::= LEADING | TRAILING | BOTH
function_invocation::= FUNCTION(function_name {, function_arg}*)
function_arg ::=
literal |
state_valued_path_expression |
input_parameter |
scalar_expression
case_expression ::=
general_case_expression |
simple_case_expression |
coalesce_expression |
nullif_expression
general_case_expression::=
CASE when_clause {when_clause}* ELSE scalar_expression END
when_clause::= WHEN conditional_expression THEN scalar_expression
simple_case_expression::=
CASE case_operand simple_when_clause {simple_when_clause}*
ELSE scalar_expression
END
case_operand::= state_valued_path_expression | type_discriminator
simple_when_clause::= WHEN scalar_expression THEN scalar_expression
coalesce_expression::= COALESCE(scalar_expression {, scalar_expression}+)
nullif_expression::= NULLIF(scalar_expression, scalar_expression)
JSR-338 Final Release
215
4/2/13
Oracle
Query Language
4/2/13
Java Persistence 2.1, Final Release
216
BNF
JSR-338 Final Release
Oracle
Metamodel API Interfaces
Ch apt er 5
Java Persistence 2.1, Final Release
Metamodel API
Metamodel API
This specification provides a set of interfaces for dynamically accessing the metamodel corresponding
to the managed classes of a persistence unit.
5.1 Metamodel API Interfaces
The javax.persistence.metamodel interfaces provide for dynamically accessing the metamodel of the persistent state and relationships of the managed classes of a persistence unit.
The metamodel can be accessed through the EntityManagerFactory or EntityManager
getMetamodel methods.
The metamodel API may be extended to cover object/relational mapping information in a future release
of this specification.
JSR-338 Final Release
217
4/2/13
Oracle
Metamodel API
Java Persistence 2.1, Final Release
Metamodel API Interfaces
5.1.1 Metamodel Interface
package javax.persistence.metamodel;
import java.util.Set;
/**
* Provides access to the metamodel of persistent
* entities in the persistence unit.
*/
public interface Metamodel {
/**
*
*
*
*
*/
<X>
/**
*
*
*
*
*
*/
<X>
/**
*
*
*
*
*
*/
<X>
Return the metamodel entity type representing the entity.
@param cls the type of the represented entity
@return the metamodel entity type
@throws IllegalArgumentException if not an entity
EntityType<X> entity(Class<X> cls);
Return the metamodel managed type representing the
entity, mapped superclass, or embeddable class.
@param cls the type of the represented managed class
@return the metamodel managed type
@throws IllegalArgumentException if not a managed class
ManagedType<X> managedType(Class<X> cls);
Return the metamodel embeddable type representing the
embeddable class.
@param cls the type of the represented embeddable class
@return the metamodel embeddable type
@throws IllegalArgumentException if not an embeddable class
EmbeddableType<X> embeddable(Class<X> cls);
/**
* Return the metamodel managed types.
* @return the metamodel managed types
*/
Set<ManagedType<?>> getManagedTypes();
/**
* Return the metamodel entity types.
* @return the metamodel entity types
*/
Set<EntityType<?>> getEntities();
}
4/2/13
/**
* Return the metamodel embeddable types.
* if there are no embeddable types.
* @return the metamodel embeddable types
*/
Set<EmbeddableType<?>> getEmbeddables();
218
Returns empty set
JSR-338 Final Release
Oracle
Metamodel API Interfaces
Java Persistence 2.1, Final Release
Metamodel API
5.1.2 Type Interface
package javax.persistence.metamodel;
/**
* Instances of the type Type represent persistent object
* or attribute types.
*
* @param <X> The type of the represented object or attribute
*/
public interface Type<X> {
public static enum PersistenceType {
ENTITY, EMBEDDABLE, MAPPED_SUPERCLASS, BASIC
}
/**
* Return the persistence type.
* @return persistence type
*/
PersistenceType getPersistenceType();
}
JSR-338 Final Release
/**
* Return the represented Java type.
* @return Java type
*/
Class<X> getJavaType();
219
4/2/13
Oracle
Metamodel API
Java Persistence 2.1, Final Release
Metamodel API Interfaces
5.1.3 ManagedType Interface
package javax.persistence.metamodel;
import java.util.Set;
/**
* Instances of the type ManagedType represent entity, mapped
* superclass, and embeddable types.
*
* @param <X> The represented type.
*/
public interface ManagedType<X> extends Type<X> {
/**
* Return the attributes of the managed type.
* @return attributes of the managed type
*/
Set<Attribute<? super X, ?>> getAttributes();
/**
* Return the attributes declared by the managed type.
* Returns empty set if the managed type has no declared
* attributes.
* @return declared attributes of the managed type
*/
Set<Attribute<X, ?>> getDeclaredAttributes();
/**
*
*
*
*
*
*
*
*/
<Y>
/**
*
*
*
*
*
*
*
*
*
*/
<Y>
4/2/13
Return the single-valued attribute of the managed
type that corresponds to the specified name and Java type.
@param name the name of the represented attribute
@param type the type of the represented attribute
@return single-valued attribute with given name and type
@throws IllegalArgumentException if attribute of the given
name and type is not present in the managed type
SingularAttribute<? super X, Y> getSingularAttribute(
String name, Class<Y> type);
Return the single-valued attribute declared by the
managed type that corresponds to the specified name and
Java type.
@param name the name of the represented attribute
@param type the type of the represented attribute
@return declared single-valued attribute of the given
name and type
@throws IllegalArgumentException if attribute of the given
name and type is not declared in the managed type
SingularAttribute<X, Y> getDeclaredSingularAttribute(
String name, Class<Y> type);
220
JSR-338 Final Release
Oracle
Metamodel API Interfaces
Java Persistence 2.1, Final Release
Metamodel API
/**
* Return the single-valued attributes of the managed type.
* Returns empty set if the managed type has no single-valued
* attributes.
* @return single-valued attributes
*/
Set<SingularAttribute<? super X, ?>> getSingularAttributes();
/**
* Return the single-valued attributes declared by the managed
* type.
* Returns empty set if the managed type has no declared
* single-valued attributes.
* @return declared single-valued attributes
*/
Set<SingularAttribute<X, ?>> getDeclaredSingularAttributes();
/**
*
*
*
*
*
*
*
*
*
*/
<E>
/**
*
*
*
*
*
*
*
*
*
*
*/
<E>
/**
*
*
*
*
*
*
*
*
*/
<E>
JSR-338 Final Release
Return the Collection-valued attribute of the managed type
that corresponds to the specified name and Java element type.
@param name the name of the represented attribute
@param elementType the element type of the represented
attribute
@return CollectionAttribute of the given name and element
type
@throws IllegalArgumentException if attribute of the given
name and type is not present in the managed type
CollectionAttribute<? super X, E> getCollection(
String name, Class<E> elementType);
Return the Collection-valued attribute declared by the
managed type that corresponds to the specified name and Java
element type.
@param name the name of the represented attribute
@param elementType the element type of the represented
attribute
@return declared CollectionAttribute of the given name and
element type
@throws IllegalArgumentException if attribute of the given
name and type is not declared in the managed type
CollectionAttribute<X, E> getDeclaredCollection(
String name, Class<E> elementType);
Return the Set-valued attribute of the managed type that
corresponds to the specified name and Java element type.
@param name the name of the represented attribute
@param elementType the element type of the represented
attribute
@return SetAttribute of the given name and element type
@throws IllegalArgumentException if attribute of the given
name and type is not present in the managed type
SetAttribute<? super X, E> getSet(String name,
Class<E> elementType);
221
4/2/13
Oracle
Metamodel API
Java Persistence 2.1, Final Release
/**
*
*
*
*
*
*
*
*
*
*/
<E>
/**
*
*
*
*
*
*
*
*
*/
<E>
/**
*
*
*
*
*
*
*
*
*
*
*/
<E>
/**
*
*
*
*
*
*
*
*
*
*
*/
<K,
4/2/13
Metamodel API Interfaces
Return the Set-valued attribute declared by the managed type
that corresponds to the specified name and Java element type.
@param name the name of the represented attribute
@param elementType the element type of the represented
attribute
@return declared SetAttribute of the given name and
element type
@throws IllegalArgumentException if attribute of the given
name and type is not declared in the managed type
SetAttribute<X, E> getDeclaredSet(String name,
Class<E> elementType);
Return the List-valued attribute of the managed type that
corresponds to the specified name and Java element type.
@param name the name of the represented attribute
@param elementType the element type of the represented
attribute
@return ListAttribute of the given name and element type
@throws IllegalArgumentException if attribute of the given
name and type is not present in the managed type
ListAttribute<? super X, E> getList(String name,
Class<E> elementType);
Return the List-valued attribute declared by the managed
type that corresponds to the specified name and Java
element type.
@param name the name of the represented attribute
@param elementType the element type of the represented
attribute
@return declared ListAttribute of the given name and
element type
@throws IllegalArgumentException if attribute of the given
name and type is not declared in the managed type
ListAttribute<X, E> getDeclaredList(String name,
Class<E> elementType);
Return the Map-valued attribute of the managed type that
corresponds to the specified name and Java key and value
types.
@param name the name of the represented attribute
@param keyType the key type of the represented attribute
@param valueType the value type of the represented attribute
@return MapAttribute of the given name and key and value
types
@throws IllegalArgumentException if attribute of the given
name and type is not present in the managed type
V> MapAttribute<? super X, K, V> getMap(String name,
Class<K> keyType,
Class<V> valueType);
222
JSR-338 Final Release
Oracle
Metamodel API Interfaces
Java Persistence 2.1, Final Release
/**
*
*
*
*
*
*
*
*
*
*
*/
<K,
Metamodel API
Return the Map-valued attribute declared by the managed
type that corresponds to the specified name and Java key
and value types.
@param name the name of the represented attribute
@param keyType the key type of the represented attribute
@param valueType the value type of the represented attribute
@return declared MapAttribute of the given name and key
and value types
@throws IllegalArgumentException if attribute of the given
name and type is not declared in the managed type
V> MapAttribute<X, K, V> getDeclaredMap(String name,
Class<K> keyType,
Class<V> valueType);
/**
* Return all multi-valued attributes (Collection-, Set-,
* List-, and Map-valued attributes) of the managed type.
* Returns empty set if the managed type has no multi-valued
* attributes.
* @return Collection-, Set-, List-, and Map-valued attributes
*/
Set<PluralAttribute<? super X, ?, ?>> getPluralAttributes();
/**
* Return all multi-valued attributes (Collection-, Set-,
* List-, and Map-valued attributes) declared by the
* managed type.
* Returns empty set if the managed type has no declared
* multi-valued attributes.
* @return declared Collection-, Set-, List-, and Map-valued
*
attributes
*/
Set<PluralAttribute<X, ?, ?>> getDeclaredPluralAttributes();
//String-based:
/**
* Return the attribute of the managed
* type that corresponds to the specified name.
* @param name the name of the represented attribute
* @return attribute with given name
* @throws IllegalArgumentException if attribute of the given
*
name is not present in the managed type
*/
Attribute<? super X, ?> getAttribute(String name);
/**
* Return the attribute declared by the managed
* type that corresponds to the specified name.
* @param name the name of the represented attribute
* @return attribute with given name
* @throws IllegalArgumentException if attribute of the given
*
name is not declared in the managed type
*/
Attribute<X, ?> getDeclaredAttribute(String name);
JSR-338 Final Release
223
4/2/13
Oracle
Metamodel API
Java Persistence 2.1, Final Release
Metamodel API Interfaces
/**
* Return the single-valued attribute of the managed type that
* corresponds to the specified name.
* @param name the name of the represented attribute
* @return single-valued attribute with the given name
* @throws IllegalArgumentException if attribute of the given
*
name is not present in the managed type
*/
SingularAttribute<? super X, ?> getSingularAttribute(
String name);
/**
* Return the single-valued attribute declared by the managed
* type that corresponds to the specified name.
* @param name the name of the represented attribute
* @return declared single-valued attribute of the given
*
name
* @throws IllegalArgumentException if attribute of the given
*
name is not declared in the managed type
*/
SingularAttribute<X, ?> getDeclaredSingularAttribute(
String name);
/**
* Return the Collection-valued attribute of the managed type
* that corresponds to the specified name.
* @param name the name of the represented attribute
* @return CollectionAttribute of the given name
* @throws IllegalArgumentException if attribute of the given
*
name is not present in the managed type
*/
CollectionAttribute<? super X, ?> getCollection(String name);
/**
* Return the Collection-valued attribute declared by the
* managed type that corresponds to the specified name.
* @param name the name of the represented attribute
* @return declared CollectionAttribute of the given name
* @throws IllegalArgumentException if attribute of the given
*
name is not declared in the managed type
*/
CollectionAttribute<X, ?> getDeclaredCollection(String name);
/**
* Return the Set-valued attribute of the managed type that
* corresponds to the specified name.
* @param name the name of the represented attribute
* @return SetAttribute of the given name
* @throws IllegalArgumentException if attribute of the given
*
name is not present in the managed type
*/
SetAttribute<? super X, ?> getSet(String name);
4/2/13
224
JSR-338 Final Release
Oracle
Metamodel API Interfaces
Java Persistence 2.1, Final Release
Metamodel API
/**
* Return the Set-valued attribute declared by the managed type
* that corresponds to the specified name.
* @param name the name of the represented attribute
* @return declared SetAttribute of the given name
* @throws IllegalArgumentException if attribute of the given
*
name is not declared in the managed type
*/
SetAttribute<X, ?> getDeclaredSet(String name);
/**
* Return the List-valued attribute of the managed type that
* corresponds to the specified name.
* @param name the name of the represented attribute
* @return ListAttribute of the given name
* @throws IllegalArgumentException if attribute of the given
*
name is not present in the managed type
*/
ListAttribute<? super X, ?> getList(String name);
/**
* Return the List-valued attribute declared by the managed
* type that corresponds to the specified name.
* @param name the name of the represented attribute
* @return declared ListAttribute of the given name
* @throws IllegalArgumentException if attribute of the given
*
name is not declared in the managed type
*/
ListAttribute<X, ?> getDeclaredList(String name);
/**
* Return the Map-valued attribute of the managed type that
* corresponds to the specified name.
* @param name the name of the represented attribute
* @return MapAttribute of the given name
* @throws IllegalArgumentException if attribute of the given
*
name is not present in the managed type
*/
MapAttribute<? super X, ?, ?> getMap(String name);
}
JSR-338 Final Release
/**
* Return the Map-valued attribute declared by the managed
* type that corresponds to the specified name.
* @param name the name of the represented attribute
* @return declared MapAttribute of the given name
* @throws IllegalArgumentException if attribute of the given
*
name is not declared in the managed type
*/
MapAttribute<X, ?, ?> getDeclaredMap(String name);
225
4/2/13
Oracle
Metamodel API
Java Persistence 2.1, Final Release
Metamodel API Interfaces
5.1.4 IdentifiableType Interface
package javax.persistence.metamodel;
import java.util.Set;
/**
* Instances of the type IdentifiableType represent entity or
* mapped superclass types.
*
* @param <X> The represented entity or mapped superclass type.
*/
public interface IdentifiableType<X> extends ManagedType<X> {
/**
*
*
*
*
*
*
*
*/
<Y>
/**
*
*
*
*
*
*
*
*
*/
<Y>
/**
*
*
*
*
*
*
*/
<Y>
/**
*
*
*
*
*
*
*
*/
<Y>
4/2/13
Return the attribute that corresponds to the id attribute of
the entity or mapped superclass.
@param type the type of the represented id attribute
@return id attribute
@throws IllegalArgumentException if id attribute of the given
type is not present in the identifiable type or if
the identifiable type has an id class
SingularAttribute<? super X, Y> getId(Class<Y> type);
Return the attribute that corresponds to the id attribute
declared by the entity or mapped superclass.
@param type the type of the represented declared
id attribute
@return declared id attribute
@throws IllegalArgumentException if id attribute of the given
type is not declared in the identifiable type or if
the identifiable type has an id class
SingularAttribute<X, Y> getDeclaredId(Class<Y> type);
Return the attribute that corresponds to the version
attribute of the entity or mapped superclass.
@param type the type of the represented version attribute
@return version attribute
@throws IllegalArgumentException if version attribute of the
given type is not present in the identifiable type
SingularAttribute<? super X, Y> getVersion(Class<Y> type);
Return the attribute that corresponds to the version
attribute declared by the entity or mapped superclass.
@param type the type of the represented declared version
attribute
@return declared version attribute
@throws IllegalArgumentException if version attribute of the
type is not declared in the identifiable type
SingularAttribute<X, Y> getDeclaredVersion(Class<Y> type);
226
JSR-338 Final Release
Oracle
Metamodel API Interfaces
Java Persistence 2.1, Final Release
Metamodel API
/**
* Return the identifiable type that corresponds to the most
* specific mapped superclass or entity extended by the entity
* or mapped superclass.
* @return supertype of identifiable type or null if no
*
such supertype
*/
IdentifiableType<? super X> getSupertype();
/**
* Whether the identifiable type has a single id attribute.
* Returns true for a simple id or embedded id; returns false
* for an idclass.
* @return boolean indicating whether the identifiable
*
type has a single id attribute
*/
boolean hasSingleIdAttribute();
/**
* Whether the identifiable type has a version attribute.
* @return boolean indicating whether the identifiable
*
type has a version attribute
*/
boolean hasVersionAttribute();
/**
*
Return the attributes corresponding to the id class of the
*
identifiable type.
*
@return id attributes
*
@throws IllegalArgumentException if the identifiable type
*
does not have an id class
*/
Set<SingularAttribute<? super X, ?>> getIdClassAttributes();
}
JSR-338 Final Release
/**
* Return the type that represents the type of the id.
* @return type of id
*/
Type<?> getIdType();
227
4/2/13
Oracle
Metamodel API
Java Persistence 2.1, Final Release
Metamodel API Interfaces
5.1.5 EntityType Interface
package javax.persistence.metamodel;
/**
* Instances of the type EntityType represent entity types.
*
* @param <X> The represented entity type.
*/
public interface EntityType<X>
extends IdentifiableType<X>, Bindable<X> {
}
/**
* Return the entity name.
* @return entity name
*/
String getName();
5.1.6 EmbeddableType Interface
package javax.persistence.metamodel;
/**
* Instances of the type EmbeddableType represent embeddable types.
*
* @param <X> The represented type.
*/
public interface EmbeddableType<X> extends ManagedType<X> {}
5.1.7 MappedSuperclassType Interface
package javax.persistence.metamodel;
/**
* Instances of the type MappedSuperclassType represent mapped
* superclass types.
*
* @param <X> The represented entity type
*/
public interface MappedSuperclassType<X>
extends IdentifiableType<X> {}
4/2/13
228
JSR-338 Final Release
Oracle
Metamodel API Interfaces
Java Persistence 2.1, Final Release
Metamodel API
5.1.8 BasicType Interface
package javax.persistence.metamodel;
/**
* Instances of the type BasicType represent basic types (including
* temporal and enumerated types).
*
* @param <X> The type of the represented basic type
*/
public interface BasicType<X> extends Type<X> {}
5.1.9 Bindable Interface
package javax.persistence.metamodel;
/**
* Instances of the type Bindable represent object or attribute types
* that can be bound into a Path.
*
* @param <T> The type of the represented object or attribute
*/
public interface Bindable<T> {
public static enum BindableType {
SINGULAR_ATTRIBUTE, PLURAL_ATTRIBUTE, ENTITY_TYPE
}
/**
* Return the bindable type of the represented object.
* @return bindable type
*/
BindableType getBindableType();
}
JSR-338 Final Release
/**
* Return the Java type of the represented object.
* If the bindable type of the object is PLURAL_ATTRIBUTE,
* the Java element type is returned. If the bindable type is
* SINGULAR_ATTRIBUTE or ENTITY_TYPE, the Java type of the
* represented entity or attribute is returned.
* @return Java type
*/
Class<T> getBindableJavaType();
229
4/2/13
Oracle
Metamodel API
Java Persistence 2.1, Final Release
Metamodel API Interfaces
5.1.10 Attribute Interface
package javax.persistence.metamodel;
/**
* Represents an attribute of
*
* @param <X> The represented
* @param <Y> The type of the
*/
public interface Attribute<X,
a Java type.
type that contains the attribute
represented attribute
Y> {
public static enum PersistentAttributeType {
MANY_TO_ONE, ONE_TO_ONE, BASIC, EMBEDDED,
MANY_TO_MANY, ONE_TO_MANY, ELEMENT_COLLECTION
}
/**
* Return the name of the attribute.
* @return name
*/
String getName();
/**
* Return the persistent attribute type for the attribute.
* @return persistent attribute type
*/
PersistentAttributeType getPersistentAttributeType();
/**
* Return the managed type representing the type in which
* the attribute was declared.
* @return declaring type
*/
ManagedType<X> getDeclaringType();
/**
* Return the Java type of the represented attribute.
* @return Java type
*/
Class<Y> getJavaType();
/**
* Return the java.lang.reflect.Member for the represented
* attribute.
* @return corresponding java.lang.reflect.Member
*/
java.lang.reflect.Member getJavaMember();
/**
* Is the attribute an association.
* @return boolean indicating whether the attribute corresponds
*
to an association
*/
boolean isAssociation();
4/2/13
230
JSR-338 Final Release
Oracle
Metamodel API Interfaces
}
Java Persistence 2.1, Final Release
Metamodel API
/**
* Is the attribute collection-valued (represents a Collection,
* Set, List, or Map).
* @return boolean indicating whether the attribute is
*
collection-valued
*/
boolean isCollection();
5.1.11 SingularAttribute Interface
package javax.persistence.metamodel;
/**
* Instances of the type SingularAttribute represents persistent
* single-valued properties or fields.
*
* @param <X> The type containing the represented attribute
* @param <T> The type of the represented attribute
*/
public interface SingularAttribute<X, T>
extends Attribute<X, T>, Bindable<T> {
/**
* Is the attribute an id attribute. This method will return
* true if the attribute is an attribute that corresponds to
* a simple id, an embedded id, or an attribute of an id class.
* @return boolean indicating whether the attribute is an id
*/
boolean isId();
/**
* Is the attribute a version attribute.
* @return boolean indicating whether the attribute is
*
a version attribute
*/
boolean isVersion();
/**
* Can the attribute be null.
* @return boolean indicating whether the attribute can be null
*/
boolean isOptional();
}
JSR-338 Final Release
/**
* Return the type that represents the type of the attribute.
* @return type of attribute
*/
Type<T> getType();
231
4/2/13
Oracle
Metamodel API
Java Persistence 2.1, Final Release
Metamodel API Interfaces
5.1.12 PluralAttribute Interface
package javax.persistence.metamodel;
/**
* Instances of the type PluralAttribute represent
* persistent collection-valued attributes.
*
* @param <X> The type the represented collection belongs to
* @param <C> The type of the represented collection
* @param <E> The element type of the represented collection
*/
public interface PluralAttribute<X, C, E>
extends Attribute<X, C>, Bindable<E> {
public static enum CollectionType {
COLLECTION, SET, LIST, MAP
}
/**
* Return the collection type.
* @return collection type
*/
CollectionType getCollectionType();
}
/**
* Return the type representing the element type of the
* collection.
* @return element type
*/
Type<E> getElementType();
5.1.13 CollectionAttribute Interface
package javax.persistence.metamodel;
/**
* Instances of the type CollectionAttribute represent persistent
* javax.util.Collection-valued attributes.
*
* @param <X> The type the represented Collection belongs to
* @param <E> The element type of the represented Collection
*/
public interface CollectionAttribute<X, E>
extends PluralAttribute<X, java.util.Collection<E>, E> {}
4/2/13
232
JSR-338 Final Release
Oracle
Metamodel API Interfaces
Java Persistence 2.1, Final Release
Metamodel API
5.1.14 SetAttribute Interface
package javax.persistence.metamodel;
/**
* Instances of the type SetAttribute represent persistent
* java.util.Set-valued attributes.
*
* @param <X> The type the represented Set belongs to
* @param <E> The element type of the represented Set
*/
public interface SetAttribute<X, E>
extends PluralAttribute<X, java.util.Set<E>, E> {}
5.1.15 ListAttribute Interface
package javax.persistence.metamodel;
/**
* Instances of the type ListAttribute represent persistent
* java.util.List-valued attributes.
*
* @param <X> The type the represented List belongs to
* @param <E> The element type of the represented List
*/
public interface ListAttribute<X, E>
extends PluralAttribute<X, java.util.List<E>, E> {}
5.1.16 MapAttribute Interface
package javax.persistence.metamodel;
/**
* Instances of the type MapAttribute represent persistent
* java.util.Map-valued attributes.
*
* @param <X> The type the represented Map belongs to
* @param <K> The type of the key of the represented Map
* @param <V> The type of the value of the represented Map
*/
public interface MapAttribute<X, K, V>
extends PluralAttribute<X, java.util.Map<K, V>, V> {
/**
* Return the Java type of the map key.
* @return Java key type
*/
Class<K> getKeyJavaType();
}
JSR-338 Final Release
/**
* Return the type representing the key type of the map.
* @return type representing key type
*/
Type<K> getKeyType();
233
4/2/13
Oracle
Metamodel API
Java Persistence 2.1, Final Release
Metamodel API Interfaces
5.1.17 StaticMetamodel Annotation
package javax.persistence.metamodel;
import
import
import
import
java.lang.annotation.ElementType;
java.lang.annotation.Retention;
java.lang.annotation.RetentionPolicy;
java.lang.annotation.Target;
/**
* The StaticMetamodel annotation specifies that the class
* is a metamodel class that represents the entity, mapped
* superclass, or embeddable class designated by the value
* element.
*/
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
public @interface StaticMetamodel {
}
4/2/13
/**
* Class being modeled by the annotated class.
*/
Class<?> value();
234
JSR-338 Final Release
Oracle
Overview
Ch apt er 6
Java Persistence 2.1, Final Release
Criteria API
Criteria API
The Java Persistence Criteria API is used to define queries through the construction of object-based
query definition objects, rather than use of the string-based approach of the Java Persistence query language described in Chapter 4.
This chapter provides the full definition of the Criteria API.
6.1 Overview
The Java Persistence Criteria API, like the Java Persistence query language is based on the abstract persistence schema of entities, their embedded objects, and their relationships as its data model. This
abstract persistence schema is materialized in the form of metamodel objects over which the Criteria
API operates. The semantics of criteria queries are designed to reflect those of Java Persistence query
language queries.
The syntax of the Criteria API is designed to allow the construction of an object-based query “graph”,
whose nodes correspond to the semantic query elements.
JSR-338 Final Release
235
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Metamodel
Java language variables can be used to reference individual nodes in a criteria query object as it is constructed and/or modified. Such variables, when used to refer to the entities and embeddable types that
constitute the query domain, play a role analogous to that of the identification variables of the Java Persistence query language.
These concepts are further described in the sections that follow. The metamodel on which criteria queries are based is presented in Chapter 5. The static metamodel classes that can be used in constructing
strongly-typed criteria queries are described in section 6.2. The javax.persistence.criteria
interfaces are presented in Section 6.3. Sections 6.4 through 6.8 describe the construction and modification of criteria query objects. Additional requirements on the persistence provider are described in section 6.9.
6.2 Metamodel
Java Persistence criteria queries are based on a metamodel of the managed classes of the persistence
unit. Static metamodel classes corresponding to the managed classes of the persistence unit can be generated by means of an annotation processor or can be created by the application developer, or the metamodel
can
be
accessed
dynamically
by
use
of
the
javax.persistence.metamodel.Metamodel interface. The getMetamodel method of the
EntityManagerFactory or EntityManager interface can be used to obtain a Metamodel
instance.
6.2.1 Static Metamodel Classes
In the typical case, an annotation processor is expected to be used to produce static metamodel classes
corresponding to the entities, mapped superclasses, and embeddable classes in the persistence unit. A
static metamodel class models the persistent state and relationships of the corresponding managed class.
For portability, an annotation processor should generate a canonical metamodel as defined below.
6.2.1.1 Canonical Metamodel
This specification defines as follows a canonical metamodel and the structure of canonical metamodel
classes.
For every managed class in the persistence unit, a corresponding metamodel class is produced as follows:
• For each managed class X in package p, a metamodel class X_ in package p is created.[73]
• The name of the metamodel class is derived from the name of the managed class by appending
"_" to the name of the managed class.
• The metamodel class X_ must be annotated with the javax.persistence.StaticMetamodel annotation[74].
[73] We expect that the option of different packages will be provided in a future release of this specification.
4/2/13
236
JSR-338 Final Release
Oracle
Metamodel
Java Persistence 2.1, Final Release
Criteria API
• If class X extends another class S, where S is the most derived managed class (i.e., entity or
mapped superclass) extended by X, then class X_ must extend class S_, where S_ is the metamodel class created for S.
• For every persistent non-collection-valued attribute y declared by class X, where the type of y
is Y, the metamodel class must contain a declaration as follows:
public static volatile SingularAttribute<X, Y> y;
• For every persistent collection-valued attribute z declared by class X, where the element type
of z is Z, the metamodel class must contain a declaration as follows:
• if the collection type of z is java.util.Collection, then
public static volatile CollectionAttribute<X, Z> z;
• if the collection type of z is java.util.Set, then
public static volatile SetAttribute<X, Z> z;
• if the collection type of z is java.util.List, then
public static volatile ListAttribute<X, Z> z;
• if the collection type of z is java.util.Map, then
public static volatile MapAttribute<X, K, Z> z;
where K is the type of the key of the map in class X
Import statements must be included for the needed javax.persistence.metamodel types as
appropriate (e.g., javax.persistence.metamodel.SingularAttribute, javax.persistence.metamodel.CollectionAttribute,
javax.persistence.metamodel.SetAttribute,
javax.persistence.metamodel.ListAttribute,
javax.persistence.metamodel.MapAttribute) and all classes X, Y, Z, and K.
Implementations of this specification are not required to support the use of non-canonical
metamodel classes. Applications that use non-canonical metamodel classes will not be portable.
[74] If the class was generated, the javax.annotation.Generated annotation should be used to annotate the class. The use of
any annotations other than StaticMetamodel and Generated on static metamodel classes is undefined.
JSR-338 Final Release
237
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Metamodel
6.2.1.2 Example
Assume the Order entity below.
package com.example;
import java.util.Set;
import java.math.BigDecimal;
@Entity public class Order {
@Id Integer orderId;
@ManyToOne Customer customer;
@OneToMany Set<Item> lineItems;
Address shippingAddress;
BigDecimal totalCost;
...
}
The corresponding canonical metamodel class, Order_, is as follows:
package com.example;
import java.math.BigDecimal;
import javax.persistence.metamodel.SingularAttribute;
import javax.persistence.metamodel.SetAttribute;
import javax.persistence.metamodel.StaticMetamodel;
@StaticMetamodel(Order.class)
public class Order_ {
public static
public static
tomer;
public static
public static
shippingAddress;
public static
totalCost;
}
volatile SingularAttribute<Order, Integer> orderId;
volatile SingularAttribute<Order, Customer> cusvolatile SetAttribute<Order, Item> lineItems;
volatile SingularAttribute<Order, Address>
volatile SingularAttribute<Order, BigDecimal>
6.2.2 Bootstrapping
When the entity manager factory for a persistence unit is created, it is the responsibility of the persistence provider to initialize the state of the metamodel classes of the persistence unit. Any generated
metamodel classes must be accessible on the classpath.
Persistence providers must support the use of canonical metamodel classes. Persistence providers may,
but are not required to, support the use of non-canonical metamodel classes.
4/2/13
238
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
6.3 Criteria API Interfaces
6.3.1 CriteriaBuilder Interface
package javax.persistence.criteria;
import
import
import
import
import
import
java.math.BigDecimal;
java.math.BigInteger;
java.util.Collection;
java.util.Map;
java.util.Set;
javax.persistence.Tuple;
/**
* Used to construct criteria queries, compound selections,
* expressions, predicates, orderings.
* Note that Predicate is used instead of Expression<Boolean>
* in this API in order to work around the fact that Java
* generics are not compatible with varags.
*/
public interface CriteriaBuilder {
/**
* Create a CriteriaQuery object.
* @return criteria query object
*/
CriteriaQuery<Object> createQuery();
/**
*
*
*
*
*/
<T>
Create a CriteriaQuery object with the specified result
type.
@param resultClass type of the query result
@return criteria query object
CriteriaQuery<T> createQuery(Class<T> resultClass);
/**
* Create a CriteriaQuery object that returns a tuple of
* objects as its result.
* @return criteria query object
*/
CriteriaQuery<Tuple> createTupleQuery();
// methods to construct queries for bulk updates and deletes:
/**
*
*
*
*/
<T>
JSR-338 Final Release
Create a query object to perform a bulk update operation.
@param targetEntity target type for update operation
@return the query object
CriteriaUpdate<T> createCriteriaUpdate(
Class<T> targetEntity);
239
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
/**
*
*
*
*/
<T>
Criteria API Interfaces
Create a query object to perform a bulk delete operation.
@param targetEntity target type for delete operation
@return the query object
CriteriaDelete<T> createCriteriaDelete(
Class<T> targetEntity);
// selection construction methods:
/**
* Create a selection item corresponding to a constructor.
* This method is used to specify a constructor that will be
* applied to the results of the query execution. If the
* constructor is for an entity class, the resulting entities
* will be in the new state after the query is executed.
* @param resultClass class whose instance is to be constructed
* @param selections arguments to the constructor
* @return compound selection item
* @throws IllegalArgumentException if an argument is a
*
tuple- or array-valued selection item
*/
<Y> CompoundSelection<Y> construct(Class<Y> resultClass,
Selection<?>... selections);
/**
* Create a tuple-valued selection item.
* @param selections selection items
* @return tuple-valued compound selection
* @throws IllegalArgumentException if an argument is a
*
tuple- or array-valued selection item
*/
CompoundSelection<Tuple> tuple(Selection<?>... selections);
/**
* Create an array-valued selection item.
* @param selections selection items
* @return array-valued compound selection
* @throws IllegalArgumentException if an argument is a
*
tuple- or array-valued selection item
*/
CompoundSelection<Object[]> array(Selection<?>... selections);
//ordering:
/**
* Create an ordering by the ascending value of the expression.
* @param x expression used to define the ordering
* @return ascending ordering corresponding to the expression
*/
Order asc(Expression<?> x);
4/2/13
240
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
/**
* Create an ordering by the descending value of the expression.
* @param x expression used to define the ordering
* @return descending ordering corresponding to the expression
*/
Order desc(Expression<?> x);
//aggregate functions:
/**
* Create an aggregate expression applying the avg operation.
* @param x expression representing input value to avg operation
* @return avg expression
*/
<N extends Number> Expression<Double> avg(Expression<N> x);
/**
* Create an aggregate expression applying the sum operation.
* @param x expression representing input value to sum operation
* @return sum expression
*/
<N extends Number> Expression<N> sum(Expression<N> x);
/**
* Create an aggregate expression applying the sum operation to
* an Integer-valued expression, returning a Long result.
* @param x expression representing input value to sum operation
* @return sum expression
*/
Expression<Long> sumAsLong(Expression<Integer> x);
/**
* Create an aggregate expression applying the sum operation to a
* Float-valued expression, returning a Double result.
* @param x expression representing input value to sum operation
* @return sum expression
*/
Expression<Double> sumAsDouble(Expression<Float> x);
/**
* Create an aggregate expression applying the numerical max
* operation.
* @param x expression representing input value to max operation
* @return max expression
*/
<N extends Number> Expression<N> max(Expression<N> x);
/**
* Create an aggregate expression applying the numerical min
* operation.
* @param x expression representing input value to min operation
* @return min expression
*/
<N extends Number> Expression<N> min(Expression<N> x);
JSR-338 Final Release
241
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
/**
* Create an aggregate expression for finding the greatest of
* the values (strings, dates, etc).
* @param x expression representing input value to greatest
*
operation
* @return greatest expression
*/
<X extends Comparable<? super X>> Expression<X> greatest(
Expression<X> x);
/**
* Create an aggregate expression for finding the least of
* the values (strings, dates, etc).
* @param x expression representing input value to least
*
operation
* @return least expression
*/
<X extends Comparable<? super X>> Expression<X> least(
Expression<X> x);
/**
* Create an aggregate expression applying the count operation.
* @param x expression representing input value to count
*
operation
* @return count expression
*/
Expression<Long> count(Expression<?> x);
/**
* Create an aggregate expression applying the count distinct
* operation.
* @param x expression representing input value to
*
count distinct operation
* @return count distinct expression
*/
Expression<Long> countDistinct(Expression<?> x);
//subqueries:
/**
* Create a predicate testing the existence of a subquery result.
* @param subquery subquery whose result is to be tested
* @return exists predicate
*/
Predicate exists(Subquery<?> subquery);
/**
* Create an all expression over the subquery results.
* @param subquery
* @return all expression
*/
<Y> Expression<Y> all(Subquery<Y> subquery);
4/2/13
242
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
/**
* Create a some expression over the subquery results.
* This expression is equivalent to an any expression.
* @param subquery
* @return some expression
*/
<Y> Expression<Y> some(Subquery<Y> subquery);
/**
* Create an any expression over the subquery results.
* This expression is equivalent to a some expression.
* @param subquery
* @return any expression
*/
<Y> Expression<Y> any(Subquery<Y> subquery);
//boolean functions:
/**
* Create a conjunction of the given boolean expressions.
* @param x boolean expression
* @param y boolean expression
* @return and predicate
*/
Predicate and(Expression<Boolean> x, Expression<Boolean> y);
/**
* Create a conjunction of the given restriction predicates.
* A conjunction of zero predicates is true.
* @param restrictions zero or more restriction predicates
* @return and predicate
*/
Predicate and(Predicate... restrictions);
/**
* Create a disjunction of the given boolean expressions.
* @param x boolean expression
* @param y boolean expression
* @return or predicate
*/
Predicate or(Expression<Boolean> x, Expression<Boolean> y);
/**
* Create a disjunction of the given restriction predicates.
* A disjunction of zero predicates is false.
* @param restrictions zero or more restriction predicates
* @return or predicate
*/
Predicate or(Predicate... restrictions);
/**
* Create a negation of the given restriction.
* @param restriction restriction expression
* @return not predicate
*/
Predicate not(Expression<Boolean> restriction);
JSR-338 Final Release
243
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
/**
* Create a conjunction (with zero conjuncts).
* A conjunction with zero conjuncts is true.
* @return and predicate
*/
Predicate conjunction();
/**
* Create a disjunction (with zero disjuncts).
* A disjunction with zero disjuncts is false.
* @return or predicate
*/
Predicate disjunction();
//turn Expression<Boolean> into a Predicate
//useful for use with varargs methods
/**
* Create a predicate testing for a true value.
* @param x expression to be tested
* @return predicate
*/
Predicate isTrue(Expression<Boolean> x);
/**
* Create a predicate testing for a false value.
* @param x expression to be tested
* @return predicate
*/
Predicate isFalse(Expression<Boolean> x);
//null tests:
/**
* Create a predicate to test whether the expression is null.
* @param x expression
* @return is-null predicate
*/
Predicate isNull(Expression<?> x);
/**
* Create a predicate to test whether the expression is not null.
* @param x expression
* @return is-not-null predicate
*/
Predicate isNotNull(Expression<?> x);
//equality:
/**
* Create a predicate for testing the arguments for equality.
* @param x expression
* @param y expression
* @return equality predicate
*/
Predicate equal(Expression<?> x, Expression<?> y);
4/2/13
244
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
/**
* Create a predicate for testing the arguments for equality.
* @param x expression
* @param y object
* @return equality predicate
*/
Predicate equal(Expression<?> x, Object y);
/**
* Create a predicate for testing the arguments for inequality.
* @param x expression
* @param y expression
* @return inequality predicate
*/
Predicate notEqual(Expression<?> x, Expression<?> y);
/**
* Create a predicate for testing the arguments for inequality.
* @param x expression
* @param y object
* @return inequality predicate
*/
Predicate notEqual(Expression<?> x, Object y);
//comparisons for generic (non-numeric) operands:
/**
* Create a predicate for testing whether the first argument is
* greater than the second.
* @param x expression
* @param y expression
* @return greater-than predicate
*/
<Y extends Comparable<? super Y>> Predicate greaterThan(
Expression<? extends Y> x, Expression<? extends Y> y);
/**
* Create a predicate for testing whether the first argument is
* greater than the second.
* @param x expression
* @param y value
* @return greater-than predicate
*/
<Y extends Comparable<? super Y>> Predicate greaterThan(
Expression<? extends Y> x, Y y);
/**
* Create a predicate for testing whether the first argument is
* greater than or equal to the second.
* @param x expression
* @param y expression
* @return greater-than-or-equal predicate
*/
<Y extends Comparable<? super Y>> Predicate greaterThanOrEqualTo(
Expression<? extends Y> x, Expression<? extends Y> y);
JSR-338 Final Release
245
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
/**
* Create a predicate for testing whether the first argument is
* greater than or equal to the second.
* @param x expression
* @param y value
* @return greater-than-or-equal predicate
*/
<Y extends Comparable<? super Y>> Predicate greaterThanOrEqualTo(
Expression<? extends Y> x, Y y);
/**
* Create a predicate for testing whether the first argument is
* less than the second.
* @param x expression
* @param y expression
* @return less-than predicate
*/
<Y extends Comparable<? super Y>> Predicate lessThan(
Expression<? extends Y> x, Expression<? extends Y> y);
/**
* Create a predicate for testing whether the first argument is
* less than the second.
* @param x expression
* @param y value
* @return less-than predicate
*/
<Y extends Comparable<? super Y>> Predicate lessThan(
Expression<? extends Y> x, Y y);
/**
* Create a predicate for testing whether the first argument is
* less than or equal to the second.
* @param x expression
* @param y expression
* @return less-than-or-equal predicate
*/
<Y extends Comparable<? super Y>> Predicate lessThanOrEqualTo(
Expression<? extends Y> x, Expression<? extends Y> y);
/**
* Create a predicate for testing whether the first argument is
* less than or equal to the second.
* @param x expression
* @param y value
* @return less-than-or-equal predicate
*/
<Y extends Comparable<? super Y>> Predicate lessThanOrEqualTo(
Expression<? extends Y> x, Y y);
4/2/13
246
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
/**
* Create a predicate for testing whether the first argument is
* between the second and third arguments in value.
* @param v expression
* @param x expression
* @param y expression
* @return between predicate
*/
<Y extends Comparable<? super Y>> Predicate between(
Expression<? extends Y> v,
Expression<? extends Y> x,
Expression<? extends Y> y);
/**
* Create a predicate for testing whether the first argument is
* between the second and third arguments in value.
* @param v expression
* @param x value
* @param y value
* @return between predicate
*/
<Y extends Comparable<? super Y>> Predicate between(
Expression<? extends Y> v, Y x, Y y);
//comparisons for numeric operands:
/**
* Create a predicate for testing whether the first argument is
* greater than the second.
* @param x expression
* @param y expression
* @return greater-than predicate
*/
Predicate gt(Expression<? extends Number> x,
Expression<? extends Number> y);
/**
* Create a predicate for testing whether the first argument is
* greater than the second.
* @param x expression
* @param y value
* @return greater-than predicate
*/
Predicate gt(Expression<? extends Number> x, Number y);
/**
* Create a predicate for testing whether the first argument is
* greater than or equal to the second.
* @param x expression
* @param y expression
* @return greater-than-or-equal predicate
*/
Predicate ge(Expression<? extends Number> x,
Expression<? extends Number> y);
JSR-338 Final Release
247
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
/**
* Create a predicate for testing whether the first argument is
* greater than or equal to the second.
* @param x expression
* @param y value
* @return greater-than-or-equal predicate
*/
Predicate ge(Expression<? extends Number> x, Number y);
/**
* Create a predicate for testing whether the first argument is
* less than the second.
* @param x expression
* @param y expression
* @return less-than predicate
*/
Predicate lt(Expression<? extends Number> x,
Expression<? extends Number> y);
/**
* Create a predicate for testing whether the first argument is
* less than the second.
* @param x expression
* @param y value
* @return less-than predicate
*/
Predicate lt(Expression<? extends Number> x, Number y);
/**
* Create a predicate for testing whether the first argument is
* less than or equal to the second.
* @param x expression
* @param y expression
* @return less-than-or-equal predicate
*/
Predicate le(Expression<? extends Number> x,
Expression<? extends Number> y);
/**
* Create a predicate for testing whether the first argument is
* less than or equal to the second.
* @param x expression
* @param y value
* @return less-than-or-equal predicate
*/
Predicate le(Expression<? extends Number> x, Number y);
//numerical operations:
/**
* Create an expression that returns the arithmetic negation
* of its argument.
* @param x expression
* @return arithmetic negation
*/
<N extends Number> Expression<N> neg(Expression<N> x);
4/2/13
248
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
/**
* Create an expression that returns the absolute value
* of its argument.
* @param x expression
* @return absolute value
*/
<N extends Number> Expression<N> abs(Expression<N> x);
/**
* Create an expression that returns the sum
* of its arguments.
* @param x expression
* @param y expression
* @return sum
*/
<N extends Number> Expression<N> sum(Expression<? extends N> x,
Expression<? extends N> y);
/**
* Create an expression that returns the sum
* of its arguments.
* @param x expression
* @param y value
* @return sum
*/
<N extends Number> Expression<N> sum(Expression<? extends N> x,
N y);
/**
* Create an expression that returns the sum
* of its arguments.
* @param x value
* @param y expression
* @return sum
*/
<N extends Number> Expression<N> sum(N x,
Expression<? extends N> y);
/**
* Create an expression that returns the product
* of its arguments.
* @param x expression
* @param y expression
* @return product
*/
<N extends Number> Expression<N> prod(Expression<? extends N> x,
Expression<? extends N> y);
/**
* Create an expression that returns the product
* of its arguments.
* @param x expression
* @param y value
* @return product
*/
<N extends Number> Expression<N> prod(Expression<? extends N> x,
N y);
JSR-338 Final Release
249
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
/**
* Create an expression that returns the product
* of its arguments.
* @param x value
* @param y expression
* @return product
*/
<N extends Number> Expression<N> prod(N x,
Expression<? extends N> y);
/**
* Create an expression that returns the difference
* between its arguments.
* @param x expression
* @param y expression
* @return difference
*/
<N extends Number> Expression<N> diff(Expression<? extends N> x,
Expression<? extends N> y);
/**
* Create an expression that returns the difference
* between its arguments.
* @param x expression
* @param y value
* @return difference
*/
<N extends Number> Expression<N> diff(Expression<? extends N> x,
N y);
/**
* Create an expression that returns the difference
* between its arguments.
* @param x value
* @param y expression
* @return difference
*/
<N extends Number> Expression<N> diff(N x,
Expression<? extends N> y);
/**
* Create an expression that returns the quotient
* of its arguments.
* @param x expression
* @param y expression
* @return quotient
*/
Expression<Number> quot(Expression<? extends Number> x,
Expression<? extends Number> y);
/**
* Create an expression that returns the quotient
* of its arguments.
* @param x expression
* @param y value
* @return quotient
*/
Expression<Number> quot(Expression<? extends Number> x, Number y);
4/2/13
250
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
/**
* Create an expression that returns the quotient
* of its arguments.
* @param x value
* @param y expression
* @return quotient
*/
Expression<Number> quot(Number x, Expression<? extends Number> y);
/**
* Create an expression that returns the modulus
* of its arguments.
* @param x expression
* @param y expression
* @return modulus
*/
Expression<Integer> mod(Expression<Integer> x,
Expression<Integer> y);
/**
* Create an expression that returns the modulus
* of its arguments.
* @param x expression
* @param y value
* @return modulus
*/
Expression<Integer> mod(Expression<Integer> x, Integer y);
/**
* Create an expression that returns the modulus
* of its arguments.
* @param x value
* @param y expression
* @return modulus
*/
Expression<Integer> mod(Integer x, Expression<Integer> y);
/**
* Create an expression that returns the square root
* of its argument.
* @param x expression
* @return square root
*/
Expression<Double> sqrt(Expression<? extends Number> x);
//typecasts:
/**
* Typecast. Returns same expression object.
* @param number numeric expression
* @return Expression<Long>
*/
Expression<Long> toLong(Expression<? extends Number> number);
JSR-338 Final Release
251
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
/**
* Typecast. Returns same expression object.
* @param number numeric expression
* @return Expression<Integer>
*/
Expression<Integer> toInteger(
Expression<? extends Number> number);
/**
* Typecast. Returns same expression object.
* @param number numeric expression
* @return Expression<Float>
*/
Expression<Float> toFloat(Expression<? extends Number> number);
/**
* Typecast. Returns same expression object.
* @param number numeric expression
* @return Expression<Double>
*/
Expression<Double> toDouble(Expression<? extends Number> number);
/**
* Typecast. Returns same expression object.
* @param number numeric expression
* @return Expression<BigDecimal>
*/
Expression<BigDecimal> toBigDecimal(
Expression<? extends Number> number);
/**
* Typecast. Returns same expression object.
* @param number numeric expression
* @return Expression<BigInteger>
*/
Expression<BigInteger> toBigInteger(
Expression<? extends Number> number);
/**
* Typecast. Returns same expression object.
* @param character expression
* @return Expression<String>
*/
Expression<String> toString(Expression<Character> character);
//literals:
/**
* Create an expression for a literal.
* @param value value represented by the expression
* @return expression literal
* @throws IllegalArgumentException if value is null
*/
<T> Expression<T> literal(T value);
4/2/13
252
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
/**
* Create an expression for a null literal with the given type.
* @param resultClass type of the null literal
* @return null expression literal
*/
<T> Expression<T> nullLiteral(Class<T> resultClass);
//parameters:
/**
* Create a parameter expression.
* @param paramClass parameter class
* @return parameter expression
*/
<T> ParameterExpression<T> parameter(Class<T> paramClass);
/**
* Create a parameter expression with the given name.
* @param paramClass parameter class
* @param name name that can be used to refer to
*
the parameter
* @return parameter expression
*/
<T> ParameterExpression<T> parameter(Class<T> paramClass,
String name);
//collection operations:
/**
* Create a predicate that tests whether a collection is empty.
* @param collection expression
* @return is-empty predicate
*/
<C extends Collection<?>> Predicate isEmpty(
Expression<C> collection);
/**
* Create a predicate that tests whether a collection is
* not empty.
* @param collection expression
* @return is-not-empty predicate
*/
<C extends Collection<?>> Predicate isNotEmpty(
Expression<C> collection);
/**
* Create an expression that tests the size of a collection.
* @param collection expression
* @return size expression
*/
<C extends Collection<?>> Expression<Integer> size(
Expression<C> collection);
JSR-338 Final Release
253
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
/**
* Create an expression that tests the size of a collection.
* @param collection collection
* @return size expression
*/
<C extends Collection<?>> Expression<Integer> size(C collection);
/**
*
*
*
*
*
*
*/
<E,
/**
*
*
*
*
*
*
*/
<E,
/**
*
*
*
*
*
*
*/
<E,
/**
*
*
*
*
*
*
*/
<E,
4/2/13
Create a predicate that tests whether an element is
a member of a collection.
If the collection is empty, the predicate will be false.
@param elem element expression
@param collection expression
@return is-member predicate
C extends Collection<E>> Predicate isMember(
Expression<E> elem, Expression<C> collection);
Create a predicate that tests whether an element is
a member of a collection.
If the collection is empty, the predicate will be false.
@param elem element
@param collection expression
@return is-member predicate
C extends Collection<E>> Predicate isMember(
E elem, Expression<C> collection);
Create a predicate that tests whether an element is
not a member of a collection.
If the collection is empty, the predicate will be true.
@param elem element expression
@param collection expression
@return is-not-member predicate
C extends Collection<E>> Predicate isNotMember(
Expression<E> elem, Expression<C> collection);
Create a predicate that tests whether an element is
not a member of a collection.
If the collection is empty, the predicate will be true.
@param elem element
@param collection expression
@return is-not-member predicate
C extends Collection<E>> Predicate isNotMember(
E elem, Expression<C> collection);
254
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
//get the values and keys collections of the Map, which may then
//be passed to size(), isMember(), isEmpty(), etc
/**
* Create an expression that returns the values of a map.
* @param map map
* @return collection expression
*/
<V, M extends Map<?, V>> Expression<Collection<V>> values(M map);
/**
* Create an expression that returns the keys of a map.
* @param map map
* @return set expression
*/
<K, M extends Map<K, ?>> Expression<Set<K>> keys(M map);
//string functions:
/**
* Create a predicate for testing whether the expression
* satisfies the given pattern.
* @param x string expression
* @param pattern string expression
* @return like predicate
*/
Predicate like(Expression<String> x, Expression<String> pattern);
/**
* Create a predicate for testing whether the expression
* satisfies the given pattern.
* @param x string expression
* @param pattern string
* @return like predicate
*/
Predicate like(Expression<String> x, String pattern);
/**
* Create a predicate for testing whether the expression
* satisfies the given pattern.
* @param x string expression
* @param pattern string expression
* @param escapeChar escape character expression
* @return like predicate
*/
Predicate like(Expression<String> x,
Expression<String> pattern,
Expression<Character> escapeChar);
JSR-338 Final Release
255
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
/**
* Create a predicate for testing whether the expression
* satisfies the given pattern.
* @param x string expression
* @param pattern string expression
* @param escapeChar escape character
* @return like predicate
*/
Predicate like(Expression<String> x,
Expression<String> pattern,
char escapeChar);
/**
* Create a predicate for testing whether the expression
* satisfies the given pattern.
* @param x string expression
* @param pattern string
* @param escapeChar escape character expression
* @return like predicate
*/
Predicate like(Expression<String> x,
String pattern,
Expression<Character> escapeChar);
/**
* Create a predicate for testing whether the expression
* satisfies the given pattern.
* @param x string expression
* @param pattern string
* @param escapeChar escape character
* @return like predicate
*/
Predicate like(Expression<String> x,
String pattern,
char escapeChar);
/**
* Create a predicate for testing whether the expression
* does not satisfy the given pattern.
* @param x string expression
* @param pattern string expression
* @return not-like predicate
*/
Predicate notLike(Expression<String> x,
Expression<String> pattern);
/**
* Create a predicate for testing whether the expression
* does not satisfy the given pattern.
* @param x string expression
* @param pattern string
* @return not-like predicate
*/
Predicate notLike(Expression<String> x, String pattern);
4/2/13
256
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
/**
* Create a predicate for testing whether the expression
* does not satisfy the given pattern.
* @param x string expression
* @param pattern string expression
* @param escapeChar escape character expression
* @return not-like predicate
*/
Predicate notLike(Expression<String> x,
Expression<String> pattern,
Expression<Character> escapeChar);
/**
* Create a predicate for testing whether the expression
* does not satisfy the given pattern.
* @param x string expression
* @param pattern string expression
* @param escapeChar escape character
* @return not-like predicate
*/
Predicate notLike(Expression<String> x,
Expression<String> pattern,
char escapeChar);
/**
* Create a predicate for testing whether the expression
* does not satisfy the given pattern.
* @param x string expression
* @param pattern string
* @param escapeChar escape character expression
* @return not-like predicate
*/
Predicate notLike(Expression<String> x,
String pattern,
Expression<Character> escapeChar);
/**
* Create a predicate for testing whether the expression
* does not satisfy the given pattern.
* @param x string expression
* @param pattern string
* @param escapeChar escape character
* @return not-like predicate
*/
Predicate notLike(Expression<String> x,
String pattern,
char escapeChar);
/**
* Create an expression for string concatenation.
* @param x string expression
* @param y string expression
* @return expression corresponding to concatenation
*/
Expression<String> concat(Expression<String> x,
Expression<String> y);
JSR-338 Final Release
257
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
/**
* Create an expression for string concatenation.
* @param x string expression
* @param y string
* @return expression corresponding to concatenation
*/
Expression<String> concat(Expression<String> x, String y);
/**
* Create an expression for string concatenation.
* @param x string
* @param y string expression
* @return expression corresponding to concatenation
*/
Expression<String> concat(String x, Expression<String> y);
/**
* Create an expression for substring extraction.
* Extracts a substring starting at the specified position
* through to end of the string.
* First position is 1.
* @param x string expression
* @param from start position expression
* @return expression corresponding to substring extraction
*/
Expression<String> substring(Expression<String> x,
Expression<Integer> from);
/**
* Create an expression for substring extraction.
* Extracts a substring starting at the specified position
* through to end of the string.
* First position is 1.
* @param x string expression
* @param from start position
* @return expression corresponding to substring extraction
*/
Expression<String> substring(Expression<String> x, int from);
/**
* Create an expression for substring extraction.
* Extracts a substring of given length starting at the
* specified position.
* First position is 1.
* @param x string expression
* @param from start position expression
* @param len length expression
* @return expression corresponding to substring extraction
*/
Expression<String> substring(Expression<String> x,
Expression<Integer> from,
Expression<Integer> len);
4/2/13
258
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
/**
* Create an expression for substring extraction.
* Extracts a substring of given length starting at the
* specified position.
* First position is 1.
* @param x string expression
* @param from start position
* @param len length
* @return expression corresponding to substring extraction
*/
Expression<String> substring(Expression<String> x,
int from,
int len);
public static enum Trimspec {
/**
* Trim from leading end.
*/
LEADING,
/**
* Trim from trailing end.
*/
TRAILING,
}
/**
* Trim from both ends.
*/
BOTH
/**
* Create expression to trim blanks from both ends of
* a string.
* @param x expression for string to trim
* @return trim expression
*/
Expression<String> trim(Expression<String> x);
/**
* Create expression to trim blanks from a string.
* @param ts trim specification
* @param x expression for string to trim
* @return trim expression
*/
Expression<String> trim(Trimspec ts, Expression<String> x);
/**
* Create expression to trim character from both ends of
* a string.
* @param t expression for character to be trimmed
* @param x expression for string to trim
* @return trim expression
*/
Expression<String> trim(Expression<Character> t,
Expression<String> x);
JSR-338 Final Release
259
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
/**
* Create expression to trim character from a string.
* @param ts trim specification
* @param t expression for character to be trimmed
* @param x expression for string to trim
* @return trim expression
*/
Expression<String> trim(Trimspec ts,
Expression<Character> t,
Expression<String> x);
/**
* Create expression to trim character from both ends of
* a string.
* @param t character to be trimmed
* @param x expression for string to trim
* @return trim expression
*/
Expression<String> trim(char t, Expression<String> x);
/**
* Create expression to trim character from a string.
* @param ts trim specification
* @param t character to be trimmed
* @param x expression for string to trim
* @return trim expression
*/
Expression<String> trim(Trimspec ts,
char t,
Expression<String> x);
/**
* Create expression for converting a string to lowercase.
* @param x string expression
* @return expression to convert to lowercase
*/
Expression<String> lower(Expression<String> x);
/**
* Create expression for converting a string to uppercase.
* @param x string expression
* @return expression to convert to uppercase
*/
Expression<String> upper(Expression<String> x);
/**
* Create expression to return length of a string.
* @param x string expression
* @return length expression
*/
Expression<Integer> length(Expression<String> x);
4/2/13
260
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
/**
* Create expression to locate the position of one string
* within another, returning position of first character
* if found.
* The first position in a string is denoted by 1. If the
* string to be located is not found, 0 is returned.
* @param x expression for string to be searched
* @param pattern expression for string to be located
* @return expression corresponding to position
*/
Expression<Integer> locate(Expression<String> x,
Expression<String> pattern);
/**
* Create expression to locate the position of one string
* within another, returning position of first character
* if found.
* The first position in a string is denoted by 1. If the
* string to be located is not found, 0 is returned.
* @param x expression for string to be searched
* @param pattern string to be located
* @return expression corresponding to position
*/
Expression<Integer> locate(Expression<String> x, String pattern);
/**
* Create expression to locate the position of one string
* within another, returning position of first character
* if found.
* The first position in a string is denoted by 1. If the
* string to be located is not found, 0 is returned.
* @param x expression for string to be searched
* @param pattern expression for string to be located
* @param from expression for position at which to start search
* @return expression corresponding to position
*/
Expression<Integer> locate(Expression<String> x,
Expression<String> pattern,
Expression<Integer> from);
/**
* Create expression to locate the position of one string
* within another, returning position of first character
* if found.
* The first position in a string is denoted by 1. If the
* string to be located is not found, 0 is returned.
* @param x expression for string to be searched
* @param pattern string to be located
* @param from position at which to start search
* @return expression corresponding to position
*/
Expression<Integer> locate(Expression<String> x,
String pattern,
int from);
JSR-338 Final Release
261
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
// Date/time/timestamp functions:
/**
* Create expression to return current date.
* @return expression for current date
*/
Expression<java.sql.Date> currentDate();
/**
* Create expression to return current timestamp.
* @return expression for current timestamp
*/
Expression<java.sql.Timestamp> currentTimestamp();
/**
* Create expression to return current time.
* @return expression for current time
*/
Expression<java.sql.Time> currentTime();
//in builders:
/**
* Interface used to build in predicates.
*/
public static interface In<T> extends Predicate {
/**
* Return the expression to be tested against the
* list of values.
* @return expression
*/
Expression<T> getExpression();
/**
* Add to list of values to be tested against.
* @param value value
* @return in predicate
*/
In<T> value(T value);
}
/**
*
*
*
*
*/
<T>
4/2/13
/**
* Add to list of values to be tested against.
* @param value expression
* @return in predicate
*/
In<T> value(Expression<? extends T> value);
Create predicate to test whether given expression
is contained in a list of values.
@param expression to be tested against list of values
@return in predicate
In<T> in(Expression<? extends T> expression);
262
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
// coalesce, nullif:
/**
* Create an expression that returns null if all its arguments
* evaluate to null, and the value of the first non-null argument
* otherwise.
* @param x expression
* @param y expression
* @return coalesce expression
*/
<Y> Expression<Y> coalesce(Expression<? extends Y> x,
Expression<? extends Y> y);
/**
* Create an expression that returns null if all its arguments
* evaluate to null, and the value of the first non-null argument
* otherwise.
* @param x expression
* @param y value
* @return coalesce expression
*/
<Y> Expression<Y> coalesce(Expression<? extends Y> x, Y y);
/**
* Create an expression that tests whether its argument are
* equal, returning null if they are and the value of the
* first expression if they are not.
* @param x expression
* @param y expression
* @return nullif expression
*/
<Y> Expression<Y> nullif(Expression<Y> x, Expression<?> y);
/**
* Create an expression that tests whether its argument are
* equal, returning null if they are and the value of the
* first expression if they are not.
* @param x expression
* @param y value
* @return nullif expression
*/
<Y> Expression<Y> nullif(Expression<Y> x, Y y);
// coalesce builder:
/**
* Interface used to build coalesce expressions.
*
* A coalesce expression is equivalent to a case expression
* that returns null if all its arguments evaluate to null,
* and the value of its first non-null argument otherwise.
*/
public static interface Coalesce<T> extends Expression<T> {
JSR-338 Final Release
263
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
/**
* Add an argument to the coalesce expression.
* @param value value
* @return coalesce expression
*/
Coalesce<T> value(T value);
}
/**
* Add an argument to the coalesce expression.
* @param value expression
* @return coalesce expression
*/
Coalesce<T> value(Expression<? extends T> value);
/**
* Create a coalesce expression.
* @return coalesce expression
*/
<T> Coalesce<T> coalesce();
//case builders:
/**
* Interface used to build simple case expressions.
* Case conditions are evaluated in the order in which
* they are specified.
*/
public static interface SimpleCase<C,R> extends Expression<R> {
/**
* Return the expression to be tested against the
* conditions.
* @return expression
*/
Expression<C> getExpression();
/**
* Add a when/then clause to the case expression.
* @param condition "when" condition
* @param result "then" result value
* @return simple case expression
*/
SimpleCase<C, R> when(C condition, R result);
/**
* Add a when/then clause to the case expression.
* @param condition "when" condition
* @param result "then" result expression
* @return simple case expression
*/
SimpleCase<C, R> when(C condition,
Expression<? extends R> result);
4/2/13
264
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
/**
* Add an "else" clause to the case expression.
* @param result "else" result
* @return expression
*/
Expression<R> otherwise(R result);
}
/**
*
*
*
*/
<C,
/**
* Add an "else" clause to the case expression.
* @param result "else" result expression
* @return expression
*/
Expression<R> otherwise(Expression<? extends R> result);
Create a simple case expression.
@param expression to be tested against the case conditions
@return simple case expression
R> SimpleCase<C,R> selectCase(
Expression<? extends C> expression);
/**
* Interface used to build general case expressions.
* Case conditions are evaluated in the order in which
* they are specified.
*/
public static interface Case<R> extends Expression<R> {
/**
* Add a when/then clause to the case expression.
* @param condition "when" condition
* @param result "then" result value
* @return general case expression
*/
Case<R> when(Expression<Boolean> condition, R result);
/**
* Add a when/then clause to the case expression.
* @param condition "when" condition
* @param result "then" result expression
* @return general case expression
*/
Case<R> when(Expression<Boolean> condition,
Expression<? extends R> result);
/**
* Add an "else" clause to the case expression.
* @param result "else" result
* @return expression
*/
Expression<R> otherwise(R result);
JSR-338 Final Release
265
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
}
Criteria API Interfaces
/**
* Add an "else" clause to the case expression.
* @param result "else" result expression
* @return expression
*/
Expression<R> otherwise(Expression<? extends R> result);
/**
* Create a general case expression.
* @return general case expression
*/
<R> Case<R> selectCase();
/**
* Create an expression for the execution of a database
* function.
* @param name function name
* @param type expected result type
* @param args function arguments
* @return expression
*/
<T> Expression<T> function(String name,
Class<T> type,
Expression<?>... args);
//methods for downcasting:
/**
*
*
*
*
*/
<X,
/**
*
*
*
*
*/
<X,
/**
*
*
*
*
*/
<X,
4/2/13
Downcast Join object to the specified type.
@param join Join object
@param type type to be downcast to
@return Join object of the specified type
T, V extends T> Join<X, V>
treat(Join<X, T> join, Class<V> type);
Downcast CollectionJoin object to the specified type.
@param join CollectionJoin object
@param type type to be downcast to
@return CollectionJoin object of the specified type
T, E extends T> CollectionJoin<X, E>
treat(CollectionJoin<X, T> join, Class<E> type);
Downcast SetJoin object to the specified type.
@param join SetJoin object
@param type type to be downcast to
@return SetJoin object of the specified type
T, E extends T> SetJoin<X, E>
treat(SetJoin<X, T> join, Class<E> type);
266
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
/**
*
*
*
*
*/
<X,
/**
*
*
*
*
*/
<X,
/**
*
*
*
*
*/
<X,
}
JSR-338 Final Release
/**
*
*
*
*
*/
<X,
Criteria API
Downcast ListJoin object to the specified type.
@param join ListJoin object
@param type type to be downcast to
@return ListJoin object of the specified type
T, E extends T> ListJoin<X, E>
treat(ListJoin<X, T> join, Class<E> type);
Downcast MapJoin object to the specified type.
@param join MapJoin object
@param type type to be downcast to
@return MapJoin object of the specified type
K, T, V extends T> MapJoin<X, K, V>
treat(MapJoin<X, K, T> join, Class<V> type);
Downcast Path object to the specified type.
@param path path
@param type type to be downcast to
@return Path object of the specified type
T extends X> Path<T> treat(Path<X> path, Class<T> type);
Downcast Root object to the specified type.
@param root root
@param type type to be downcast to
@return Root object of the specified type
T extends X> Root<T> treat(Root<X> root, Class<T> type);
267
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
6.3.2 CommonAbstractCriteria Interface
package javax.persistence.criteria;
/**
* The CommonAbstractCriteria interface defines functionality
* that is common to both top-level criteria queries and subqueries
* as well as to update and delete criteria operations.
* It is not intended to be used directly in query construction.
*
* Note that criteria queries and criteria update and delete
* operations are typed differently.
* Criteria queries are typed according to the query result type.
* Update and delete operations are typed according to the target
* of the update or delete.*
*/
public interface CommonAbstractCriteria {
/**
* Create a subquery of the query.
* @param type the subquery result type
* @return subquery
*/
<U> Subquery<U> subquery(Class<U> type);
}
4/2/13
/**
* Return the predicate that corresponds to the where clause
* restriction(s), or null if no restrictions have been
* specified.
* @return where clause predicate
*/
Predicate getRestriction();
268
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
6.3.3 AbstractQuery Interface
package javax.persistence.criteria;
import java.util.List;
import java.util.Set;
import javax.persistence.metamodel.EntityType;
/**
* The AbstractQuery interface defines functionality that is common
* to both top-level queries and subqueries.
* It is not intended to be used directly in query construction.
*
* All queries must have:
*
a set of root entities (which may in turn own joins)
* All queries may have:
*
a conjunction of restrictions.
*
* @param <T> type of the result
*/
public interface AbstractQuery<T> extends CommonAbstractCriteria {
/**
* Create and add a query root corresponding to the given entity,
* forming a cartesian product with any existing roots.
* @param entityClass the entity class
* @return query root corresponding to the given entity
*/
<X> Root<X> from(Class<X> entityClass);
/**
* Create and add a query root corresponding to the given entity,
* forming a cartesian product with any existing roots.
* @param entity metamodel entity representing the entity
*
of type X
* @return query root corresponding to the given entity
*/
<X> Root<X> from(EntityType<X> entity);
/**
* Modify the query to restrict the query results according
* to the specified boolean expression.
* Replaces the previously added restriction(s), if any.
* @param restriction a simple or compound boolean expression
* @return the modified query
*/
AbstractQuery<T> where(Expression<Boolean> restriction);
/**
* Modify the query to restrict the query results according
* to the conjunction of the specified restriction predicates.
* Replaces the previously added restriction(s), if any.
* If no restrictions are specified, any previously added
* restrictions are simply removed.
* @param restrictions zero or more restriction predicates
* @return the modified query
*/
AbstractQuery<T> where(Predicate... restrictions);
JSR-338 Final Release
269
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
/**
* Specify the expressions that are used to form groups over
* the query results.
* Replaces the previous specified grouping expressions, if any.
* If no grouping expressions are specified, any previously
* added grouping expressions are simply removed.
* @param grouping zero or more grouping expressions
* @return the modified query
*/
AbstractQuery<T> groupBy(Expression<?>... grouping);
/**
* Specify the expressions that are used to form groups over
* the query results.
* Replaces the previous specified grouping expressions, if any.
* If no grouping expressions are specified, any previously
* added grouping expressions are simply removed.
* @param grouping list of zero or more grouping expressions
* @return the modified query
*/
AbstractQuery<T> groupBy(List<Expression<?>> grouping);
/**
* Specify a restriction over the groups of the query.
* Replaces the previous having restriction(s), if any.
* @param restriction a simple or compound boolean expression
* @return the modified query
*/
AbstractQuery<T> having(Expression<Boolean> restriction);
/**
* Specify restrictions over the groups of the query
* according the conjunction of the specified restriction
* predicates.
* Replaces the previously added having restriction(s), if any.
* If no restrictions are specified, any previously added
* restrictions are simply removed.
* @param restrictions zero or more restriction predicates
* @return the modified query
*/
AbstractQuery<T> having(Predicate... restrictions);
/**
* Specify whether duplicate query results will be eliminated.
* A true value will cause duplicates to be eliminated.
* A false value will cause duplicates to be retained.
* If distinct has not been specified, duplicate results must
* be retained.
* @param distinct boolean value specifying whether duplicate
*
results must be eliminated from the query result or
*
whether they must be retained
* @return the modified query
*/
AbstractQuery<T> distinct(boolean distinct);
4/2/13
270
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
/**
* Return the query roots. These are the roots that have
* been defined for the CriteriaQuery or Subquery itself,
* including any subquery roots defined as a result of
* correlation. Returns empty set if no roots have been defined.
* Modifications to the set do not affect the query.
* @return the set of query roots
*/
Set<Root<?>> getRoots();
/**
* Return the selection of the query, or null if no selection
* has been set.
* @return selection item
*/
Selection<T> getSelection();
/**
* Return a list of the grouping expressions. Returns empty
* list if no grouping expressions have been specified.
* Modifications to the list do not affect the query.
* @return the list of grouping expressions
*/
List<Expression<?>> getGroupList();
/**
* Return the predicate that corresponds to the restriction(s)
* over the grouping items, or null if no restrictions have
* been specified.
* @return having clause predicate
*/
Predicate getGroupRestriction();
/**
* Return whether duplicate query results must be eliminated or
* retained.
* @return boolean indicating whether duplicate query results
*
must be eliminated
*/
boolean isDistinct();
}
JSR-338 Final Release
/**
* Return the result type of the query or subquery.
* If a result type was specified as an argument to the
* createQuery or subquery method, that type will be returned.
* If the query was created using the createTupleQuery
* method, the result type is Tuple.
* Otherwise, the result type is Object.
* @return result type
*/
Class<T> getResultType();
271
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
6.3.4 CriteriaQuery Interface
package javax.persistence.criteria;
import java.util.List;
import java.util.Set;
/**
* The CriteriaQuery interface defines functionality that is specific
* to top-level queries.
*
* @param <T> type of the defined result
*/
public interface CriteriaQuery<T> extends AbstractQuery<T> {
/**
* Specify the item that is to be returned in the query result.
* Replaces the previously specified selection(s), if any.
*
* Note: Applications using the string-based API may need to
* specify the type of the select item when it results from
* a get or join operation and the query result type is
* specified. For example:
*
* CriteriaQuery<String> q = cb.createQuery(String.class);
* Root<Order> order = q.from(Order.class);
* q.select(order.get("shippingAddress").<String>get("state"));
*
* CriteriaQuery<Product> q2 = cb.createQuery(Product.class);
* q2.select(q2.from(Order.class)
*
.join("items")
*
.<Item,Product>join("product"));
*
* @param selection selection specifying the item that
*
is to be returned in the query result
* @return the modified query
* @throws IllegalArgumentException if the selection is
*
a compound selection and more than one selection
*
item has the same assigned alias
*/
CriteriaQuery<T> select(Selection<? extends T> selection);
/**
* Specify the selection items that are to be returned in the
* query result.
* Replaces the previously specified selection(s), if any.
*
* The type of the result of the query execution depends on
* the specification of the type of the criteria query object
* created as well as the arguments to the multiselect method.
* An argument to the multiselect method must not be a tuple* or array-valued compound selection item.
*
* The semantics of this method are as follows:
*
* If the type of the criteria query is CriteriaQuery<Tuple>
* (i.e., a criteria query object created by either the
* createTupleQuery method or by passing a Tuple class argument
* to the createQuery method), a Tuple object corresponding to
* the arguments of the multiselect method, in the specified
4/2/13
272
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
* order, will be instantiated and returned for each row that
* results from the query execution.
*
* If the type of the criteria query is CriteriaQuery<X> for
* some user-defined class X (i.e., a criteria query object
* created by passing a X class argument to the createQuery
* method), the arguments to the multiselect method will be
* passed to the X constructor and an instance of type X will be
* returned for each row.
*
* If the type of the criteria query is CriteriaQuery<X[]> for
* some class X, an instance of type X[] will be returned for
* each row.
The elements of the array will correspond to the
* arguments of the multiselect method, in the specified order.
*
* If the type of the criteria query is CriteriaQuery<Object>
* or if the criteria query was created without specifying a
* type, and only a single argument is passed to the multiselect
* method, an instance of type Object will be returned for
* each row.
*
* If the type of the criteria query is CriteriaQuery<Object>
* or if the criteria query was created without specifying a
* type, and more than one argument is passed to the multiselect
* method, an instance of type Object[] will be instantiated
* and returned for each row. The elements of the array will
* correspond to the arguments to the multiselect method, in the
* specified order.
*
* @param selections selection items corresponding to the
*
results to be returned by the query
* @return the modified query
* @throws IllegalArgumentException if a selection item is
*
not valid or if more than one selection item has
*
the same assigned alias
*/
CriteriaQuery<T> multiselect(Selection<?>... selections);
/**
* Specify the selection items that are to be returned in the
* query result.
* Replaces the previously specified selection(s), if any.
*
* The type of the result of the query execution depends on
* the specification of the type of the criteria query object
* created as well as the argument to the multiselect method.
* An element of the list passed to the multiselect method
* must not be a tuple- or array-valued compound selection item.
*
* The semantics of this method are as follows:
*
* If the type of the criteria query is CriteriaQuery<Tuple>
* (i.e., a criteria query object created by either the
* createTupleQuery method or by passing a Tuple class argument
* to the createQuery method), a Tuple object corresponding to
* the elements of the list passed to the multiselect method,
* in the specified order, will be instantiated and returned
* for each row that results from the query execution.
*
JSR-338 Final Release
273
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
* If the type of the criteria query is CriteriaQuery<X> for
* some user-defined class X (i.e., a criteria query object
* created by passing a X class argument to the createQuery
* method), the elements of the list passed to the multiselect
* method will be passed to the X constructor and an instance
* of type X will be returned for each row.
*
* If the type of the criteria query is CriteriaQuery<X[]> for
* some class X, an instance of type X[] will be returned for
* each row.
The elements of the array will correspond to the
* elements of the list passed to the multiselect method, in
* the specified order.
*
* If the type of the criteria query is CriteriaQuery<Object>
* or if the criteria query was created without specifying a
* type, and the list passed to the multiselect method contains
* only a single element, an instance of type Object will be
* returned for each row.
*
* If the type of the criteria query is CriteriaQuery<Object>
* or if the criteria query was created without specifying a
* type, and the list passed to the multiselect method contains
* more than one element, an instance of type Object[] will be
* instantiated and returned for each row. The elements of the
* array will correspond to the elements of the list passed to
* the multiselect method, in the specified order.
*
* @param selectionList list of selection items corresponding
*
to the results to be returned by the query
* @return the modified query
* @throws IllegalArgumentException if a selection item is
*
not valid or if more than one selection item has
*
the same assigned alias
*/
CriteriaQuery<T> multiselect(List<Selection<?>> selectionList);
/**
* Modify the query to restrict the query result according
* to the specified boolean expression.
* Replaces the previously added restriction(s), if any.
* This method only overrides the return type of the
* corresponding AbstractQuery method.
* @param restriction a simple or compound boolean expression
* @return the modified query
*/
CriteriaQuery<T> where(Expression<Boolean> restriction);
/**
* Modify the query to restrict the query result according
* to the conjunction of the specified restriction predicates.
* Replaces the previously added restriction(s), if any.
* If no restrictions are specified, any previously added
* restrictions are simply removed.
* This method only overrides the return type of the
* corresponding AbstractQuery method.
* @param restrictions zero or more restriction predicates
* @return the modified query
*/
CriteriaQuery<T> where(Predicate... restrictions);
4/2/13
274
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
/**
* Specify the expressions that are used to form groups over
* the query results.
* Replaces the previous specified grouping expressions, if any.
* If no grouping expressions are specified, any previously
* added grouping expressions are simply removed.
* This method only overrides the return type of the
* corresponding AbstractQuery method.
* @param grouping zero or more grouping expressions
* @return the modified query
*/
CriteriaQuery<T> groupBy(Expression<?>... grouping);
/**
* Specify the expressions that are used to form groups over
* the query results.
* Replaces the previous specified grouping expressions, if any.
* If no grouping expressions are specified, any previously
* added grouping expressions are simply removed.
* This method only overrides the return type of the
* corresponding AbstractQuery method.
* @param grouping list of zero or more grouping expressions
* @return the modified query
*/
CriteriaQuery<T> groupBy(List<Expression<?>> grouping);
/**
* Specify a restriction over the groups of the query.
* Replaces the previous having restriction(s), if any.
* This method only overrides the return type of the
* corresponding AbstractQuery method.
* @param restriction a simple or compound boolean expression
* @return the modified query
*/
CriteriaQuery<T> having(Expression<Boolean> restriction);
/**
* Specify restrictions over the groups of the query
* according the conjunction of the specified restriction
* predicates.
* Replaces the previously added having restriction(s), if any.
* If no restrictions are specified, any previously added
* restrictions are simply removed.
* This method only overrides the return type of the
* corresponding AbstractQuery method.
* @param restrictions zero or more restriction predicates
* @return the modified query
*/
CriteriaQuery<T> having(Predicate... restrictions);
/**
* Specify the ordering expressions that are used to
* order the query results.
* Replaces the previous ordering expressions, if any.
* If no ordering expressions are specified, the previous
* ordering, if any, is simply removed, and results will
* be returned in no particular order.
* The left-to-right sequence of the ordering expressions
JSR-338 Final Release
275
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
* determines the precedence, whereby the leftmost has highest
* precedence.
* @param o zero or more ordering expressions
* @return the modified query
*/
CriteriaQuery<T> orderBy(Order... o);
/**
* Specify the ordering expressions that are used to
* order the query results.
* Replaces the previous ordering expressions, if any.
* If no ordering expressions are specified, the previous
* ordering, if any, is simply removed, and results will
* be returned in no particular order.
* The order of the ordering expressions in the list
* determines the precedence, whereby the first element in the
* list has highest precedence.
* @param o list of zero or more ordering expressions
* @return the modified query
*/
CriteriaQuery<T> orderBy(List<Order> o);
/**
* Specify whether duplicate query results will be eliminated.
* A true value will cause duplicates to be eliminated.
* A false value will cause duplicates to be retained.
* If distinct has not been specified, duplicate results must
* be retained.
* This method only overrides the return type of the
* corresponding AbstractQuery method.
* @param distinct boolean value specifying whether duplicate
*
results must be eliminated from the query result or
*
whether they must be retained
* @return the modified query.
*/
CriteriaQuery<T> distinct(boolean distinct);
/**
* Return the ordering expressions in order of precedence.
* Returns empty list if no ordering expressions have been
* specified.
* Modifications to the list do not affect the query.
* @return the list of ordering expressions
*/
List<Order> getOrderList();
}
4/2/13
/**
* Return the parameters of the query. Returns empty set if
* there are no parameters.
* Modifications to the set do not affect the query.
* @return the query parameters
*/
Set<ParameterExpression<?>> getParameters();
276
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
6.3.5 CriteriaUpdate Interface
package javax.persistence.criteria;
import javax.persistence.metamodel.SingularAttribute;
import javax.persistence.metamodel.EntityType;
/**
* The CriteriaUpdate interface defines functionality for performing
* bulk update operations using the Criteria API.
*
* Criteria API bulk update operations map directly to database update
* operations, bypassing any optimistic locking checks. Portable
* applications using bulk update operations must manually update the
* value of the version column, if desired, and/or manually validate
* the value of the version column.
* The persistence context is not synchronized with the result of the
* bulk update.
*
* A CriteriaUpdate object must have a single root.
*
* @param <T> the entity type that is the target of the update
*/
public interface CriteriaUpdate<T> extends CommonAbstractCriteria {
/**
* Create and add a query root corresponding to the entity
* that is the target of the update.
* A CriteriaUpdate object has a single root, the entity that
* is being updated.
* @param entityClass the entity class
* @return query root corresponding to the given entity
*/
Root<T> from(Class<T> entityClass);
/**
* Create and add a query root corresponding to the entity
* that is the target of the update.
* A CriteriaUpdate object has a single root, the entity that
* is being updated.
* @param entity metamodel entity representing the entity
*
of type X
* @return query root corresponding to the given entity
*/
Root<T> from(EntityType<T> entity);
/**
* Return the query root.
* @return the query root
*/
Root<T> getRoot();
JSR-338 Final Release
277
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
/**
* Update the value of the specified attribute.
* @param attribute attribute to be updated
* @param value new value
* @return the modified update query
*/
<Y, X extends Y> CriteriaUpdate<T> set(
SingularAttribute<? super T, Y> attribute,
X value);
/**
* Update the value of the specified attribute.
* @param attribute attribute to be updated
* @param value new value
* @return the modified update query
*/
<Y> CriteriaUpdate<T> set(
SingularAttribute<? super T, Y> attribute,
Expression<? extends Y> value);
/**
* Update the value of the specified attribute.
* @param attribute attribute to be updated
* @param value new value
* @return the modified update query
*/
<Y, X extends Y> CriteriaUpdate<T> set(Path<Y> attribute, X value);
/**
* Update the value of the specified attribute.
* @param attribute attribute to be updated
* @param value new value
* @return the modified update query
*/
<Y> CriteriaUpdate<T> set(Path<Y> attribute,
Expression<? extends Y> value);
/**
* Update the value of the specified attribute.
* @param attributeName name of the attribute to be updated
* @param value new value
* @return the modified update query
*/
CriteriaUpdate<T> set(String attributeName, Object value);
/**
* Modify the update query to restrict the target of the update
* according to the specified boolean expression.
* Replaces the previously added restriction(s), if any.
* @param restriction a simple or compound boolean expression
* @return the modified update query
*/
CriteriaUpdate<T> where(Expression<Boolean> restriction);
4/2/13
278
JSR-338 Final Release
Oracle
Criteria API Interfaces
}
JSR-338 Final Release
Java Persistence 2.1, Final Release
Criteria API
/**
* Modify the update query to restrict the target of the update
* according to the conjunction of the specified restriction
* predicates.
* Replaces the previously added restriction(s), if any.
* If no restrictions are specified, any previously added
* restrictions are simply removed.
* @param restrictions zero or more restriction predicates
* @return the modified update query
*/
CriteriaUpdate<T> where(Predicate... restrictions);
279
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
6.3.6 CriteriaDelete Interface
package javax.persistence.criteria;
import javax.persistence.metamodel.EntityType;
/**
* The CriteriaDelete interface defines functionality for performing
* bulk delete operations using the Criteria API
*
* Criteria API bulk delete operations map directly to database
* delete operations. The persistence context is not synchronized
* with the result of the bulk delete.
*
* A CriteriaDelete object must have a single root.
*
* @param <T> the entity type that is the target of the delete*
*/
public interface CriteriaDelete<T> extends CommonAbstractCriteria {
/**
* Create and add a query root corresponding to the entity
* that is the target of the delete.
* A CriteriaDelete object has a single root, the entity that
* is being deleted.
* @param entityClass the entity class
* @return query root corresponding to the given entity
*/
Root<T> from(Class<T> entityClass);
/**
* Create and add a query root corresponding to the entity
* that is the target of the delete.
* A CriteriaDelete object has a single root, the entity that
* is being deleted.
* @param entity metamodel entity representing the entity
*
of type X
* @return query root corresponding to the given entity
*/
Root<T> from(EntityType<T> entity);
/**
* Return the query root.
* @return the query root
*/
Root<T> getRoot();
/**
* Modify the delete query to restrict the target of the
* deletion according to the specified boolean expression.
* Replaces the previously added restriction(s), if any.
* @param restriction a simple or compound boolean expression
* @return the modified delete query
*/
CriteriaDelete<T> where(Expression<Boolean> restriction);
4/2/13
280
JSR-338 Final Release
Oracle
Criteria API Interfaces
}
JSR-338 Final Release
Java Persistence 2.1, Final Release
Criteria API
/**
* Modify the delete query to restrict the target of the
* deletion according to the conjunction of the specified
* restriction predicates.
* Replaces the previously added restriction(s), if any.
* If no restrictions are specified, any previously added
* restrictions are simply removed.
* @param restrictions zero or more restriction predicates
* @return the modified delete query
*/
CriteriaDelete<T> where(Predicate... restrictions);
281
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
6.3.7 Subquery Interface
package javax.persistence.criteria;
import java.util.List;
import java.util.Set;
/**
* The Subquery interface defines functionality that is
* specific to subqueries.
*
* A subquery has an expression as its selection item.
*
* @param <T> the type of the selection item.
*/
public interface Subquery<T>
extends AbstractQuery<T>, Expression<T> {
/**
* Specify the item that is to be returned as the subquery
* result.
* Replaces the previously specified selection, if any.
* @param expression expression specifying the item that
*
is to be returned as the subquery result
* @return the modified subquery
*/
Subquery<T> select(Expression<T> expression);
/**
* Modify the subquery to restrict the result according
* to the specified boolean expression.
* Replaces the previously added restriction(s), if any.
* This method only overrides the return type of the
* corresponding AbstractQuery method.
* @param restriction a simple or compound boolean expression
* @return the modified subquery
*/
Subquery<T> where(Expression<Boolean> restriction);
/**
* Modify the subquery to restrict the result according
* to the conjunction of the specified restriction predicates.
* Replaces the previously added restriction(s), if any.
* If no restrictions are specified, any previously added
* restrictions are simply removed.
* This method only overrides the return type of the
* corresponding AbstractQuery method.
* @param restrictions zero or more restriction predicates
* @return the modified subquery
*/
Subquery<T> where(Predicate... restrictions);
4/2/13
282
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
/**
* Specify the expressions that are used to form groups over
* the subquery results.
* Replaces the previous specified grouping expressions, if any.
* If no grouping expressions are specified, any previously
* added grouping expressions are simply removed.
* This method only overrides the return type of the
* corresponding AbstractQuery method.
* @param grouping zero or more grouping expressions
* @return the modified subquery
*/
Subquery<T> groupBy(Expression<?>... grouping);
/**
* Specify the expressions that are used to form groups over
* the subquery results.
* Replaces the previous specified grouping expressions, if any.
* If no grouping expressions are specified, any previously
* added grouping expressions are simply removed.
* This method only overrides the return type of the
* corresponding AbstractQuery method.
* @param grouping list of zero or more grouping expressions
* @return the modified subquery
*/
Subquery<T> groupBy(List<Expression<?>> grouping);
/**
* Specify a restriction over the groups of the subquery.
* Replaces the previous having restriction(s), if any.
* This method only overrides the return type of the
* corresponding AbstractQuery method.
* @param restriction a simple or compound boolean expression
* @return the modified subquery
*/
Subquery<T> having(Expression<Boolean> restriction);
/**
* Specify restrictions over the groups of the subquery
* according the conjunction of the specified restriction
* predicates.
* Replaces the previously added having restriction(s), if any.
* If no restrictions are specified, any previously added
* restrictions are simply removed.
* This method only overrides the return type of the
* corresponding AbstractQuery method.
* @param restrictions zero or more restriction predicates
* @return the modified subquery
*/
Subquery<T> having(Predicate... restrictions);
JSR-338 Final Release
283
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
/**
* Specify whether duplicate query results will be eliminated.
* A true value will cause duplicates to be eliminated.
* A false value will cause duplicates to be retained.
* If distinct has not been specified, duplicate results must
* be retained.
* This method only overrides the return type of the
* corresponding AbstractQuery method.
* @param distinct boolean value specifying whether duplicate
*
results must be eliminated from the subquery result or
*
whether they must be retained
* @return the modified subquery.
*/
Subquery<T> distinct(boolean distinct);
/**
* Create a subquery root correlated to a root of the
* enclosing query.
* @param parentRoot a root of the containing query
* @return subquery root
*/
<Y> Root<Y> correlate(Root<Y> parentRoot);
/**
* Create a subquery join object correlated to a join object
* of the enclosing query.
* @param parentJoin join object of the containing query
* @return subquery join
*/
<X, Y> Join<X, Y> correlate(Join<X, Y> parentJoin);
/**
* Create a subquery collection join object correlated to a
* collection join object of the enclosing query.
* @param parentCollection join object of the containing query
* @return subquery join
*/
<X, Y> CollectionJoin<X, Y> correlate(
CollectionJoin<X, Y> parentCollection);
/**
* Create a subquery set join object correlated to a set join
* object of the enclosing query.
* @param parentSet join object of the containing query
* @return subquery join
*/
<X, Y> SetJoin<X, Y> correlate(SetJoin<X, Y> parentSet);
/**
* Create a subquery list join object correlated to a list join
* object of the enclosing query.
* @param parentList join object of the containing query
* @return subquery join
*/
<X, Y> ListJoin<X, Y> correlate(ListJoin<X, Y> parentList);
4/2/13
284
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
/**
* Create a subquery map join object correlated to a map join
* object of the enclosing query.
* @param parentMap join object of the containing query
* @return subquery join
*/
<X, K, V> MapJoin<X, K, V> correlate(MapJoin<X, K, V> parentMap);
/**
* Return the query of which this is a subquery.
* @return the enclosing query or subquery
*/
AbstractQuery<?> getParent();
/**
* Return the query of which this is a subquery.
* This may be a CriteriaQuery, CriteriaUpdate, CriteriaDelete,
* or a Subquery.
* @return the enclosing query or subquery
*/
CommonAbstractCriteria getContainingQuery();
/**
* Return the selection expression.
* @return the item to be returned in the subquery result
*/
Expression<T> getSelection();
}
JSR-338 Final Release
/**
* Return the correlated joins of the subquery (Join objects
* obtained as a result of the use of the correlate method).
* Returns empty set if the subquery has no correlated
* joins.
* Modifications to the set do not affect the query.
* @return the correlated joins of the subquery
*/
Set<Join<?, ?>> getCorrelatedJoins();
285
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
6.3.8 Selection Interface
package javax.persistence.criteria;
import javax.persistence.TupleElement;
import java.util.List;
/**
* The Selection interface defines an item that is to be
* returned in a query result.
*
* @param <X> the type of the selection item
*/
public interface Selection<X> extends TupleElement<X> {
/**
* Assigns an alias to the selection item.
* Once assigned, an alias cannot be changed or reassigned.
* Returns the same selection item.
* @param name alias
* @return selection item
*/
Selection<X> alias(String name);
/**
* Whether the selection item is a compound selection.
* @return boolean indicating whether the selection is a
*
compound selection
*/
boolean isCompoundSelection();
}
/**
* Return the selection items composing a compound selection.
* Modifications to the list do not affect the query.
* @return list of selection items
* @throws IllegalStateException if selection is not a compound
*
selection
*/
List<Selection<?>> getCompoundSelectionItems();
6.3.9 CompoundSelection Interface
package javax.persistence.criteria;
/**
* The CompoundSelection interface defines a compound selection item
* (tuple, array, or result of constructor).
*
* @param <X> the type of the selection item
*/
public interface CompoundSelection<X> extends Selection<X> {}
4/2/13
286
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
6.3.10 Expression Interface
package javax.persistence.criteria;
import java.util.Collection;
/**
* Type for query expressions.
*
* @param <T> the type of the expression
*/
public interface Expression<T> extends Selection<T> {
/**
* Create a predicate to test whether the expression is null.
* @return predicate testing whether the expression is null
*/
Predicate isNull();
/**
* Create a predicate to test whether the expression is
* not null.
* @return predicate testing whether the expression is not null
*/
Predicate isNotNull();
/**
* Create a predicate to test whether the expression is a member
* of the argument list.
* @param values values to be tested against
* @return predicate testing for membership
*/
Predicate in(Object... values);
/**
* Create a predicate to test whether the expression is a member
* of the argument list.
* @param values expressions to be tested against
* @return predicate testing for membership
*/
Predicate in(Expression<?>... values);
/**
* Create a predicate to test whether the expression is a member
* of the collection.
* @param values collection of values to be tested against
* @return predicate testing for membership
*/
Predicate in(Collection<?> values);
/**
* Create a predicate to test whether the expression is a member
* of the collection.
* @param values expression corresponding to collection to be
*
tested against
* @return predicate testing for membership
*/
Predicate in(Expression<Collection<?>> values);
JSR-338 Final Release
287
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
}
4/2/13
Criteria API Interfaces
/**
* Perform a typecast upon the expression, returning a new
* expression object.
* This method does not cause type conversion:
* the runtime type is not changed.
* Warning: may result in a runtime failure.
* @param type intended type of the expression
* @return new expression of the given type
*/
<X> Expression<X> as(Class<X> type);
288
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
6.3.11 Predicate Interface
package javax.persistence.criteria;
import java.util.List;
/**
* The type of a simple or compound predicate: a conjunction or
* disjunction of restrictions.
* A simple predicate is considered to be a conjunction with a
* single conjunct.
*/
public interface Predicate extends Expression<Boolean> {
public static enum BooleanOperator {
AND, OR
}
/**
* Return the boolean operator for the predicate.
* If the predicate is simple, this is AND.
* @return boolean operator for the predicate
*/
BooleanOperator getOperator();
/**
* Whether the predicate has been created from another
* predicate by applying the Predicate not() method or the
* CriteriaBuilder not() method.
* @return boolean indicating if the predicate is
*
a negated predicate
*/
boolean isNegated();
/**
* Return the top-level conjuncts or disjuncts of the predicate.
* Returns empty list if there are no top-level conjuncts or
* disjuncts of the predicate.
* Modifications to the list do not affect the query.
* @return list of boolean expressions forming the predicate
*/
List<Expression<Boolean>> getExpressions();
}
JSR-338 Final Release
/**
* Create a negation of the predicate.
* @return negated predicate
*/
Predicate not();
289
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
6.3.12 Path Interface
package javax.persistence.criteria;
import
import
import
import
javax.persistence.metamodel.PluralAttribute;
javax.persistence.metamodel.SingularAttribute;
javax.persistence.metamodel.Bindable;
javax.persistence.metamodel.MapAttribute;
/**
* Represents a simple or compound attribute path from a
* bound type or collection, and is a "primitive" expression.
*
* @param <X> the type referenced by the path
*/
public interface Path<X> extends Expression<X> {
/**
* Return the bindable object that corresponds to the
* path expression.
* @return bindable object corresponding to the path
*/
Bindable<X> getModel();
/**
* Return the parent "node" in the path or null if no parent.
* @return parent
*/
Path<?> getParentPath();
/**
*
*
*
*
*/
<Y>
/**
*
*
*
*
*/
<E,
/**
*
*
*
*
*/
<K,
4/2/13
Create a path corresponding to the referenced
single-valued attribute.
@param attribute single-valued attribute
@return path corresponding to the referenced attribute
Path<Y> get(SingularAttribute<? super X, Y> attribute);
Create a path corresponding to the referenced
collection-valued attribute.
@param collection collection-valued attribute
@return expression corresponding to the referenced attribute
C extends java.util.Collection<E>> Expression<C> get(
PluralAttribute<X, C, E> collection);
Create a path corresponding to the referenced
map-valued attribute.
@param map map-valued attribute
@return expression corresponding to the referenced attribute
V, M extends java.util.Map<K, V>> Expression<M> get(
MapAttribute<X, K, V> map);
290
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
/**
* Create an expression corresponding to the type of the path.
* @return expression corresponding to the type of the path
*/
Expression<Class<? extends X>> type();
//String-based:
}
JSR-338 Final Release
/**
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*/
<Y>
Create a path corresponding to the referenced attribute.
Note: Applications using the string-based API may need to
specify the type resulting from the get operation in order
to avoid the use of Path variables.
For example:
CriteriaQuery<Person> q = cb.createQuery(Person.class);
Root<Person> p = q.from(Person.class);
q.select(p)
.where(cb.isMember("joe",
p.<Set<String>>get("nicknames")));
rather than:
CriteriaQuery<Person> q = cb.createQuery(Person.class);
Root<Person> p = q.from(Person.class);
Path<Set<String>> nicknames = p.get("nicknames");
q.select(p)
.where(cb.isMember("joe", nicknames));
@param attributeName name of the attribute
@return path corresponding to the referenced attribute
@throws IllegalStateException if invoked on a path that
corresponds to a basic type
@throws IllegalArgumentException if attribute of the given
name does not otherwise exist
Path<Y> get(String attributeName);
291
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
6.3.13 FetchParent Interface
package javax.persistence.criteria;
import javax.persistence.metamodel.PluralAttribute;
import javax.persistence.metamodel.SingularAttribute;
/**
* Represents an element of the from clause which may
* function as the parent of Fetches.
*
* @param <Z> the source type
* @param <X> the target type
*/
public interface FetchParent<Z, X> {
/**
* Return the fetch joins that have been made from this type.
* Returns empty set if no fetch joins have been made from
* this type.
* Modifications to the set do not affect the query.
* @return fetch joins made from this type
*/
java.util.Set<Fetch<X, ?>> getFetches();
/**
*
*
*
*
*/
<Y>
/**
*
*
*
*
*
*/
<Y>
/**
*
*
*
*
*/
<Y>
/**
*
*
*
*
*
*/
<Y>
4/2/13
Create a fetch join to the specified single-valued attribute
using an inner join.
@param attribute target of the join
@return the resulting fetch join
Fetch<X, Y> fetch(SingularAttribute<? super X, Y> attribute);
Create a fetch join to the specified single-valued attribute
using the given join type.
@param attribute target of the join
@param jt join type
@return the resulting fetch join
Fetch<X, Y> fetch(SingularAttribute<? super X, Y> attribute,
JoinType jt);
Create a fetch join to the specified collection-valued
attribute using an inner join.
@param attribute target of the join
@return the resulting join
Fetch<X, Y> fetch(PluralAttribute<? super X, ?, Y> attribute);
Create a fetch join to the specified collection-valued
attribute using the given join type.
@param attribute target of the join
@param jt join type
@return the resulting join
Fetch<X, Y> fetch(PluralAttribute<? super X, ?, Y> attribute,
JoinType jt);
292
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
//String-based:
/**
*
*
*
*
*
*
*
*/
<X,
}
JSR-338 Final Release
/**
*
*
*
*
*
*
*
*
*/
<X,
Create a fetch join to the specified attribute using an
inner join.
@param attributeName name of the attribute for the
target of the join
@return the resulting fetch join
@throws IllegalArgumentException if attribute of the given
name does not exist
Y> Fetch<X, Y> fetch(String attributeName);
Create a fetch join to the specified attribute using
the given join type.
@param attributeName name of the attribute for the
target of the join
@param jt join type
@return the resulting fetch join
@throws IllegalArgumentException if attribute of the given
name does not exist
Y> Fetch<X, Y> fetch(String attributeName, JoinType jt);
293
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
6.3.14 Fetch Interface
package javax.persistence.criteria;
import javax.persistence.metamodel.Attribute;
/**
* Represents a join-fetched association or attribute.
*
* @param <Z> the source type of the fetch
* @param <X> the target type of the fetch
*/
public interface Fetch<Z, X> extends FetchParent<Z, X> {
/**
* Return the metamodel attribute corresponding to the
* fetch join.
* @return metamodel attribute for the join
*/
Attribute<? super Z, ?> getAttribute();
/**
* Return the parent of the fetched item.
* @return fetch parent
*/
FetchParent<?, Z> getParent();
}
4/2/13
/**
* Return the join type used in the fetch join.
* @return join type
*/
JoinType getJoinType();
294
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
6.3.15 From Interface
package javax.persistence.criteria;
import
import
import
import
import
import
javax.persistence.metamodel.SingularAttribute;
javax.persistence.metamodel.CollectionAttribute;
javax.persistence.metamodel.ListAttribute;
javax.persistence.metamodel.MapAttribute;
javax.persistence.metamodel.SetAttribute;
java.util.Set;
/**
* Represents a bound type, usually an entity that appears in
* the from clause, but may also be an embeddable belonging to
* an entity in the from clause.
* Serves as a factory for Joins of associations, embeddables, and
* collections belonging to the type, and for Paths of attributes
* belonging to the type.
*
* @param <Z> the source type
* @param <X> the target type
*/
public interface From<Z, X> extends Path<X>, FetchParent<Z, X> {
/**
* Return the joins that have been made from this bound type.
* Returns empty set if no joins have been made from this
* bound type.
* Modifications to the set do not affect the query.
* @return joins made from this type
*/
Set<Join<X, ?>> getJoins();
/**
* Whether the From object has been obtained as a result of
* correlation (use of a Subquery correlate method).
* @return boolean indicating whether the object has been
*
obtained through correlation
*/
boolean isCorrelated();
/**
* Returns the parent From object from which the correlated
* From object has been obtained through correlation (use
* of a Subquery correlate method).
* @return the parent of the correlated From object
* @throws IllegalStateException if the From object has
*
not been obtained through correlation
*/
From<Z, X> getCorrelationParent();
/**
*
*
*
*
*/
<Y>
JSR-338 Final Release
Create an inner join to the specified single-valued
attribute.
@param attribute target of the join
@return the resulting join
Join<X, Y> join(SingularAttribute<? super X, Y> attribute);
295
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
/**
*
*
*
*
*
*/
<Y>
/**
*
*
*
*
*/
<Y>
/**
*
*
*
*/
<Y>
/**
*
*
*
*/
<Y>
/**
*
*
*
*/
<K,
/**
*
*
*
*
*
*/
<Y>
/**
*
*
*
*
*
*/
<Y>
4/2/13
Criteria API Interfaces
Create a join to the specified single-valued attribute
using the given join type.
@param attribute target of the join
@param jt join type
@return the resulting join
Join<X, Y> join(SingularAttribute<? super X, Y> attribute,
JoinType jt);
Create an inner join to the specified Collection-valued
attribute.
@param collection target of the join
@return the resulting join
CollectionJoin<X, Y> join(
CollectionAttribute<? super X, Y> collection);
Create an inner join to the specified Set-valued attribute.
@param set target of the join
@return the resulting join
SetJoin<X, Y> join(SetAttribute<? super X, Y> set);
Create an inner join to the specified List-valued attribute.
@param list target of the join
@return the resulting join
ListJoin<X, Y> join(ListAttribute<? super X, Y> list);
Create an inner join to the specified Map-valued attribute.
@param map target of the join
@return the resulting join
V> MapJoin<X, K, V> join(MapAttribute<? super X, K, V> map);
Create a join to the specified Collection-valued attribute
using the given join type.
@param collection target of the join
@param jt join type
@return the resulting join
CollectionJoin<X, Y> join(
CollectionAttribute<? super X, Y> collection, JoinType jt);
Create a join to the specified Set-valued attribute using
the given join type.
@param set target of the join
@param jt join type
@return the resulting join
SetJoin<X, Y> join(SetAttribute<? super X, Y> set,
JoinType jt);
296
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
/**
*
*
*
*
*
*/
<Y>
/**
*
*
*
*
*
*/
<K,
Criteria API
Create a join to the specified List-valued attribute using
the given join type.
@param list target of the join
@param jt join type
@return the resulting join
ListJoin<X, Y> join(ListAttribute<? super X, Y> list,
JoinType jt);
Create a join to the specified Map-valued attribute using
the given join type.
@param map target of the join
@param jt join type
@return the resulting join
V> MapJoin<X, K, V> join(MapAttribute<? super X, K, V> map,
JoinType jt);
//String-based:
/**
*
*
*
*
*
*
*/
<X,
/**
*
*
*
*
*
*
*
*/
<X,
/**
*
*
*
*
*
*
*/
<X,
JSR-338 Final Release
Create an inner join to the specified attribute.
@param attributeName name of the attribute for the
target of the join
@return the resulting join
@throws IllegalArgumentException if attribute of the given
name does not exist
Y> Join<X, Y> join(String attributeName);
Create an inner join to the specified Collection-valued
attribute.
@param attributeName name of the attribute for the
target of the join
@return the resulting join
@throws IllegalArgumentException if attribute of the given
name does not exist
Y> CollectionJoin<X, Y> joinCollection(String attributeName);
Create an inner join to the specified Set-valued attribute.
@param attributeName name of the attribute for the
target of the join
@return the resulting join
@throws IllegalArgumentException if attribute of the given
name does not exist
Y> SetJoin<X, Y> joinSet(String attributeName);
297
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
/**
*
*
*
*
*
*
*/
<X,
/**
*
*
*
*
*
*
*/
<X,
/**
*
*
*
*
*
*
*
*
*/
<X,
/**
*
*
*
*
*
*
*
*
*/
<X,
/**
*
*
*
*
*
*
*
*
*/
<X,
4/2/13
Criteria API Interfaces
Create an inner join to the specified List-valued attribute.
@param attributeName name of the attribute for the
target of the join
@return the resulting join
@throws IllegalArgumentException if attribute of the given
name does not exist
Y> ListJoin<X, Y> joinList(String attributeName);
Create an inner join to the specified Map-valued attribute.
@param attributeName name of the attribute for the
target of the join
@return the resulting join
@throws IllegalArgumentException if attribute of the given
name does not exist
K, V> MapJoin<X, K, V> joinMap(String attributeName);
Create a join to the specified attribute using the given
join type.
@param attributeName name of the attribute for the
target of the join
@param jt join type
@return the resulting join
@throws IllegalArgumentException if attribute of the given
name does not exist
Y> Join<X, Y> join(String attributeName, JoinType jt);
Create a join to the specified Collection-valued attribute
using the given join type.
@param attributeName name of the attribute for the
target of the join
@param jt join type
@return the resulting join
@throws IllegalArgumentException if attribute of the given
name does not exist
Y> CollectionJoin<X, Y> joinCollection(String attributeName,
JoinType jt);
Create a join to the specified Set-valued attribute using
the given join type.
@param attributeName name of the attribute for the
target of the join
@param jt join type
@return the resulting join
@throws IllegalArgumentException if attribute of the given
name does not exist
Y> SetJoin<X, Y> joinSet(String attributeName, JoinType jt);
298
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
/**
*
*
*
*
*
*
*
*
*/
<X,
/**
*
*
*
*
*
*
*
*
*/
<X,
}
Criteria API
Create a join to the specified List-valued attribute using
the given join type.
@param attributeName name of the attribute for the
target of the join
@param jt join type
@return the resulting join
@throws IllegalArgumentException if attribute of the given
name does not exist
Y> ListJoin<X, Y> joinList(String attributeName, JoinType jt);
Create a join to the specified Map-valued attribute using
the given join type.
@param attributeName name of the attribute for the
target of the join
@param jt join type
@return the resulting join
@throws IllegalArgumentException if attribute of the given
name does not exist
K, V> MapJoin<X, K, V> joinMap(String attributeName,
JoinType jt);
6.3.16 Root Interface
package javax.persistence.criteria;
import javax.persistence.metamodel.EntityType;
/**
* A root type in the from clause.
* Query roots always reference entities.
*
* @param <X> the entity type referenced by the root
*/
public interface Root<X> extends From<X, X> {
}
JSR-338 Final Release
/**
* Return the metamodel entity corresponding to the root.
* @return metamodel entity corresponding to the root
*/
EntityType<X> getModel();
299
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
6.3.17 Join Interface
package javax.persistence.criteria;
import javax.persistence.metamodel.Attribute;
/**
* A join to an entity, embeddable, or basic type.
*
* @param <Z> the source type of the join
* @param <X> the target type of the join
*/
public interface Join<Z, X> extends From<Z, X> {
/**
* Modify the join to restrict the result according to the
* specified ON condition. Replaces the previous ON condition,
* if any.
* Return the join object
* @param restriction a simple or compound boolean expression
* @return the modified join object
*/
Join<Z, X> on(Expression<Boolean> restriction);
/**
* Modify the join to restrict the result according to the
* specified ON condition. Replaces the previous ON condition,
* if any.
* Return the join object
* @param restrictions zero or more restriction predicates
* @return the modified join object
*/
Join<Z, X> on(Predicate... restrictions);
/**
* Return the predicate that corresponds to the ON
* restriction(s) on the join, or null if no ON condition
* has been specified.
* @return the ON restriction predicate
*/
Predicate getOn();
/**
* Return the metamodel attribute corresponding to the join.
* @return metamodel attribute corresponding to the join
*/
Attribute<? super Z, ?> getAttribute();
/**
* Return the parent of the join.
* @return join parent
*/
From<?, Z> getParent();
}
4/2/13
/**
* Return the join type.
* @return join type
*/
JoinType getJoinType();
300
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
6.3.18 JoinType
package javax.persistence.criteria;
/**
* Defines the three types of joins.
*
* Right outer joins and right outer fetch joins are not required
* to be supported in Java Persistence 2.1. Applications that use
* RIGHT join types will not be portable.
*/
public enum JoinType {
/**
* Inner join.
*/
INNER,
/**
* Left outer join.
*/
LEFT,
}
/**
* Right outer join.
*/
RIGHT
6.3.19 PluralJoin Interface
package javax.persistence.criteria;
import javax.persistence.metamodel.PluralAttribute;
/**
* The PluralJoin interface defines functionality
* that is common to joins to all collection types. It is
* not intended to be used directly in query construction.
*
* @param <Z> the source type
* @param <C> the collection type
* @param <E> the element type of the collection
*/
public interface PluralJoin<Z, C, E> extends Join<Z, E> {
}
JSR-338 Final Release
/**
* Return the metamodel representation for the collection-valued
* attribute corresponding to the join.
* @return metamodel collection-valued attribute corresponding
*
to the target of the join
*/
PluralAttribute<? super Z, C, E> getModel();
301
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
6.3.20 CollectionJoin Interface
package javax.persistence.criteria;
import java.util.Collection;
import javax.persistence.metamodel.CollectionAttribute;
/**
* The CollectionJoin interface is the type of the result of
* joining to a collection over an association or element
* collection that has been specified as a java.util.Collection.
*
* @param <Z> the source type of the join
* @param <E> the element type of the target Collection
*/
public interface CollectionJoin<Z, E>
extends PluralJoin<Z, Collection<E>, E> {
/**
* Modify the join to restrict the result according to the
* specified ON condition. Replaces the previous ON condition,
* if any.
* Return the join object
* @param restriction a simple or compound boolean expression
* @return the modified join object
*/
CollectionJoin<Z, E> on(Expression<Boolean> restriction);
/**
* Modify the join to restrict the result according to the
* specified ON condition. Replaces the previous ON condition,
* if any.
* Return the join object
* @param restrictions zero or more restriction predicates
* @return the modified join object
*/
CollectionJoin<Z, E> on(Predicate... restrictions);
}
4/2/13
/**
* Return the metamodel representation for the collection
* attribute.
* @return metamodel type representing the Collection that is
*
the target of the join
*/
CollectionAttribute<? super Z, E> getModel();
302
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
6.3.21 SetJoin Interface
package javax.persistence.criteria;
import java.util.Set;
import javax.persistence.metamodel.SetAttribute;
/**
* The SetJoin interface is the type of the result of
* joining to a collection over an association or element
* collection that has been specified as a java.util.Set.
*
* @param <Z> the source type of the join
* @param <E> the element type of the target Set
*/
public interface SetJoin<Z, E> extends PluralJoin<Z, Set<E>, E> {
/**
* Modify the join to restrict the result according to the
* specified ON condition. Replaces the previous ON condition,
* if any.
* Return the join object
* @param restriction a simple or compound boolean expression
* @return the modified join object
*/
SetJoin<Z, E> on(Expression<Boolean> restriction);
/**
* Modify the join to restrict the result according to the
* specified ON condition. Replaces the previous ON condition,
* if any.
* Return the join object
* @param restrictions zero or more restriction predicates
* @return the modified join object
*/
SetJoin<Z, E> on(Predicate... restrictions);
}
JSR-338 Final Release
/**
* Return the metamodel representation for the set attribute.
* @return metamodel type representing the Set that is
*
the target of the join
*/
SetAttribute<? super Z, E> getModel();
303
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Criteria API Interfaces
6.3.22 ListJoin Interface
package javax.persistence.criteria;
import java.util.List;
import javax.persistence.metamodel.ListAttribute;
/**
* The ListJoin interface is the type of the result of
* joining to a collection over an association or element
* collection that has been specified as a java.util.List.
*
* @param <Z> the source type of the join
* @param <E> the element type of the target List
*/
public interface ListJoin<Z, E> extends PluralJoin<Z, List<E>, E> {
/**
* Modify the join to restrict the result according to the
* specified ON condition. Replaces the previous ON condition,
* if any.
* Return the join object
* @param restriction a simple or compound boolean expression
* @return the modified join object
*/
ListJoin<Z, E> on(Expression<Boolean> restriction);
/**
* Modify the join to restrict the result according to the
* specified ON condition. Replaces the previous ON condition,
* if any.
* Return the join object
* @param restrictions zero or more restriction predicates
* @return the modified join object
*/
ListJoin<Z, E> on(Predicate... restrictions);
/**
* Return the metamodel representation for the list attribute.
* @return metamodel type representing the List that is
*
the target of the join
*/
ListAttribute<? super Z, E> getModel();
}
4/2/13
/**
* Create an expression that corresponds to the index of
* the object in the referenced association or element
* collection.
* This method must only be invoked upon an object that
* represents an association or element collection for
* which an order column has been defined.
* @return expression denoting the index
*/
Expression<Integer> index();
304
JSR-338 Final Release
Oracle
Criteria API Interfaces
Java Persistence 2.1, Final Release
Criteria API
6.3.23 MapJoin Interface
package javax.persistence.criteria;
import java.util.Map;
import javax.persistence.metamodel.MapAttribute;
/**
* The MapJoin interface is the type of the result of
* joining to a collection over an association or element
* collection that has been specified as a java.util.Map.
*
* @param <Z> the source type of the join
* @param <K> the type of the target Map key
* @param <V> the type of the target Map value
*/
public interface MapJoin<Z, K, V>
extends PluralJoin<Z, Map<K, V>, V> {
/**
* Modify the join to restrict the result according to the
* specified ON condition. Replaces the previous ON condition,
* if any.
* Return the join object
* @param restriction a simple or compound boolean expression
* @return the modified join object
*/
MapJoin<Z, K, V> on(Expression<Boolean> restriction);
/**
* Modify the join to restrict the result according to the
* specified ON condition. Replaces the previous ON condition,
* if any.
* Return the join object
* @param restrictions zero or more restriction predicates
* @return the modified join object
*/
MapJoin<Z, K, V> on(Predicate... restrictions);
/**
* Return the metamodel representation for the map attribute.
* @return metamodel type representing the Map that is
*
the target of the join
*/
MapAttribute<? super Z, K, V> getModel();
/**
* Create a path expression that corresponds to the map key.
* @return path corresponding to map key
*/
Path<K> key();
/**
* Create a path expression that corresponds to the map value.
* This method is for stylistic use only: it just returns this.
* @return path corresponding to the map value
*/
Path<V> value();
JSR-338 Final Release
305
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
}
Criteria API Interfaces
/**
* Create an expression that corresponds to the map entry.
* @return expression corresponding to the map entry
*/
Expression<Map.Entry<K, V>> entry();
6.3.24 Order Interface
package javax.persistence.criteria;
/**
* An object that defines an ordering over the query results.
*/
public interface Order {
/**
* Switch the ordering.
* @return a new Order instance with the reversed ordering
*/
Order reverse();
/**
* Whether ascending ordering is in effect.
* @return boolean indicating whether ordering is ascending
*/
boolean isAscending();
}
/**
* Return the expression that is used for ordering.
* @return expression used for ordering
*/
Expression<?> getExpression();
6.3.25 ParameterExpression Interface
package javax.persistence.criteria;
import javax.persistence.Parameter;
/**
* Type of criteria query parameter expressions.
*
* @param <T> the type of the parameter expression
*/
public interface ParameterExpression<T>
extends Parameter<T>, Expression<T> {}
4/2/13
306
JSR-338 Final Release
Oracle
Criteria Query API Usage
Java Persistence 2.1, Final Release
Criteria API
6.4 Criteria Query API Usage
The javax.persistence.criteria API interfaces are designed both to allow criteria queries to
be constructed in a strongly-typed manner, using metamodel objects to provide type safety, and to allow
for string-based use as an alternative:
• Metamodel objects are used to specify navigation through joins and through path expres-
sions[75]. Typesafe navigation is achieved by specification of the source and target types of the
navigation.
• Strings may be used as an alternative to metamodel objects, whereby joins and navigation are
specified by use of strings that correspond to attribute names.
Using either the approach based on metamodel objects or the string-based approach, queries can be constructed both statically and dynamically. Both approaches are equivalent in terms of the range of queries
that can be expressed and operational semantics.
Section 6.5 provides a description of the use of the criteria API interfaces. This section is illustrated on
the basis of the construction of strongly-typed queries using static metamodel classes. Section 6.6
describes how the javax.persistence.metamodel API can be used to construct strongly-typed
queries in the absence of such classes. String-based use of the criteria API is described in section 6.7.
6.5 Constructing Criteria Queries
A criteria query is constructed through the creation and modification of a javax.persistence.criteria.CriteriaQuery object.
The CriteriaBuilder interface is used to construct CriteriaQuery, CriteriaUpdate, and
CriteriaDelete objects. The CriteriaBuilder implementation is accessed through the getCriteriaBuilder method of the EntityManager or EntityManagerFactory interface.
For example:
...
@PersistenceUnit EntityManagerFactory emf;
CriteriaBuilder cb = emf.getCriteriaBuilder();
6.5.1 CriteriaQuery Creation
A CriteriaQuery object is created by means of one of the createQuery methods or the createTupleQuery method of the CriteriaBuilder interface. A CriteriaQuery object is
typed according to its expected result type when the CriteriaQuery object is created. A
TypedQuery instance created from the CriteriaQuery object by means of the EntityManager createQuery method will result in instances of this type when the resulting query is executed.
[75] The attributes of these metamodel objects play a role analogous to that which would be played by member literals.
JSR-338 Final Release
307
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Constructing Criteria Queries
The following methods are provided for the creation of CriteriaQuery objects:
<T> CriteriaQuery<T> createQuery(Class<T> resultClass);
CriteriaQuery<Tuple> createTupleQuery();
CriteriaQuery<Object> createQuery();
Methods for the creation of update and delete queries are described in section 6.5.15.
The methods <T> CriteriaQuery<T> createQuery(Class<T> resultClass) and createTupleQuery provide for typing of criteria query results and for typesafe query execution using
the TypedQuery API.
The effect of the createTupleQuery method is semantically equivalent to invoking the createQuery method with the Tuple.class argument. The Tuple interface supports the extraction of
multiple selection items in a strongly typed manner. See sections 3.10.3 and 3.10.4.
The CriteriaQuery<Object> createQuery() method supports both the case where the
select or multiselect method specifies only a single selection item and where the multiselect method specifies multiple selection items. If only a single item is specified, an instance of type
Object will be returned for each result of the query execution. If multiple selection items are specified, an instance of type Object[] will be instantiated and returned for each result of the execution.
See section 6.5.11, “Specifying the Select List” for further discussion of the specification of selection
items.
6.5.2 Query Roots
A CriteriaQuery object defines a query over one or more entity, embeddable, or basic abstract
schema types. The root objects of the query are entities, from which the other types are reached by navigation. A query root plays a role analogous to that of a range variable in the Java Persistence query language and forms the basis for defining the domain of the query.
A query root is created and added to the query by use of the from method of the AbstractQuery
interface (from which both the CriteriaQuery and Subquery interfaces inherit). The argument to
the from method is the entity class or EntityType instance for the entity. The result of the from
method is a Root object. The Root interface extends the From interface, which represents objects that
may occur in the from clause of a query.
A CriteriaQuery object may have more than one root. The addition of a query root has the semantic effect of creating a cartesian product between the entity type referenced by the added root and those
of the other roots.
4/2/13
308
JSR-338 Final Release
Oracle
Constructing Criteria Queries
Java Persistence 2.1, Final Release
Criteria API
The following query illustrates the definition of a query root. When executed, this query causes all
instances of the Customer entity to be returned.
CriteriaBuilder cb = ...
CriteriaQuery<Customer> q = cb.createQuery(Customer.class);
Root<Customer> customer = q.from(Customer.class);
q.select(customer);
6.5.3 Joins
The join methods of the From interface extend the query domain by creating a join with a related
class that can be navigated to or that is an element of the given class of the query domain.
The target of the join is specified by the corresponding SingularAttribute or collection-valued
attribute (CollectionAttribute, SetAttribute, ListAttribute, or MapAttribute) of
the corresponding metamodel class.[76] [77]
The join methods may be applied to instances of the Root and Join types.
The result of a join method is a Join object (instance of the Join, CollectionJoin, SetJoin,
ListJoin, or MapJoin types) that captures the source and target types of the join.
For example, given the Order entity and corresponding Order_ metamodel class shown in section
6.2.1.2, a join to the lineItems of the order would be expressed as follows:
CriteriaQuery<Order> q = cb.createQuery(Order.class);
Root<Order> order = q.from(Order.class);
Join<Order, Item> item = order.join(Order_.lineItems);
q.select(order);
The argument to the join method, Order_.lineItems, is of type javax.persistence.metamodel.SetAttribute<Order, Item>.
The join methods have the same semantics as the corresponding Java Persistence query language
operations, as described in section 4.4.7.
Example:
CriteriaBuilder cb = ...
CriteriaQuery<String> q = cb.createQuery(String.class);
Root<Customer> customer = q.from(Customer.class);
Join<Customer, Order> order = customer.join(Customer_.orders);
Join<Order, Item> item = order.join(Order_.lineItems);
q.select(customer.get(Customer_.name))
.where(cb.equal(item.get(Item_.product).get(Product_.productType),
"printer"));
[76] Metamodel objects are used to specify typesafe nagivation through joins and through path expressions. These metamodel objects
capture both the source and target types of the attribute through which navigation occurs, and are thus the mechanism by which
typesafe navigation is achieved.
[77] Attribute names serve this role for string-based queries. See section 6.7.
JSR-338 Final Release
309
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Constructing Criteria Queries
This query is equivalent to the following Java Persistence query language query:
SELECT c.name
FROM Customer c JOIN c.orders o JOIN o.lineItems i
WHERE i.product.productType = 'printer'
Joins can be chained, thus allowing this query to be written more concisely:
CriteriaQuery<String> q = cb.createQuery(String.class);
Root<Customer> customer = q.from(Customer.class);
Join<Order, Item> item =
customer.join(Customer_.orders).join(Order_.lineItems);
q.select(customer.get(Customer_.name))
.where(cb.equal(item.get(Item_.product).get(Product_.productType),
"printer"));
By default, the join method defines an inner join. Outer joins are defined by specifying a JoinType
argument. Only left outer joins and left outer fetch joins are required to be supported in Java Persistence
2.1. Applications that make use of right outer joins or right outer fetch joins will not be portable.
The following query uses a left outer join:
CriteriaQuery<Customer> q = cb.createQuery(Customer.class);
Root<Customer> customer = q.from(Customer.class);
Join<Customer,Order> order =
customer.join(Customer_.orders, JoinType.LEFT);
q.where(cb.equal(customer.get(Customer_.status), 1))
.select(customer);
This query is equivalent to the following Java Persistence query language query:
SELECT c FROM Customer c LEFT JOIN c.orders o WHERE c.status = 1
On-conditions can be specified for joins. The following query uses an on-condition with a left outer
join:
CriteriaQuery<Tuple> q = cb.createTupleQuery();
Root<Supplier> s = q.from(Supplier.class);
Join<Supplier, Product> p =
s.join(Supplier_.products, JoinType.LEFT);
p.on(cb.equal(p.get(Product_.status), "inStock"));
q.groupBy(s.get(Supplier_.name));
q.multiselect(s.get(Supplier_.name), cb.count(p));
This query is equivalent to the following Java Persistence query language query:
SELECT s.name, COUNT(p)
FROM Suppliers s LEFT JOIN s.products p
ON p.status = 'inStock'
GROUP BY s.name
4/2/13
310
JSR-338 Final Release
Oracle
Constructing Criteria Queries
Java Persistence 2.1, Final Release
Criteria API
6.5.4 Fetch Joins
Fetch joins are specified by means of the fetch method. The fetch method specifies that the referenced association or attribute is to be fetched as a side effect of the execution of the query. The fetch
method can be applied to a Root or Join instance.
An association or attribute referenced by the fetch method must be referenced from an entity or
embeddable that is returned as the result of the query. A fetch join has the same join semantics as the
corresponding inner or outer join, except that the related objects are not top-level objects in the query
result and cannot be referenced elsewhere by the query. See Section 4.4.5.3.
The fetch method must not be used in a subquery.
Multiple levels of fetch joins are not required to be supported by an implementation of this specification. Applications that use multi-level fetch joins will not be portable.
Example:
CriteriaQuery<Department> q = cb.createQuery(Department.class);
Root<Department> d = q.from(Department.class);
d.fetch(Department_.employees, JoinType.LEFT);
q.where(cb.equal(d.get(Department_.deptno), 1)).select(d);
This query is equivalent to the following Java Persistence query language query:
SELECT d
FROM Department d LEFT JOIN FETCH d.employees
WHERE d.deptno = 1
6.5.5 Path Navigation
A Path instance can be a Root instance, a Join instance, a Path instance that has been derived from
another Path instance by means of the get navigation method, or a Path instance derived from a
map-valued association or element collection by use of the key or value method.
When a criteria query is executed, path navigation—like path navigation using the Java Persistence
query language—is obtained using “inner join” semantics. That is, if the value of a non-terminal Path
instance is null, the path is considered to have no value, and does not participate in the determination of
the query result. See Section 4.4.4.
The get method is used for path navigation. The argument to the get method is specified by the corresponding SingularAttribute or collection-valued attribute (CollectionAttribute,
SetAttribute, ListAttribute, or MapAttribute) of the corresponding metamodel class[78].
Example 1:
In the following example, ContactInfo is an embeddable class consisting of an address and set of
phones. Phone is an entity.
[78] Attribute names serve this role for string-based queries. See section 6.7.
JSR-338 Final Release
311
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Constructing Criteria Queries
CriteriaQuery<Vendor> q = cb.createQuery(Vendor.class);
Root<Employee> emp = q.from(Employee.class);
Join<ContactInfo, Phone> phone =
emp.join(Employee_.contactInfo).join(ContactInfo_.phones);
q.where(cb.equal(emp.get(Employee_.contactInfo)
.get(ContactInfo_.address)
.get(Address_.zipcode),
"95054"))
.select(phone.get(Phone_.vendor));
The following Java Persistence query language query is equivalent:
SELECT p.vendor
FROM Employee e JOIN e.contactInfo.phones p
WHERE e.contactInfo.address.zipcode = '95054'
Example 2:
In this example, the photos attribute corresponds to a map from photo label to filename. The map key
is a string, the value an object. The result of this query will be returned as a Tuple object whose elements are of types String and Object. The multiselect method, described further in section
6.5.11, “Specifying the Select List”, is used to specify that the query returns multiple selection items.
CriteriaQuery<Tuple> q = cb.createTupleQuery();
Root<Item> item = q.from(Item.class);
MapJoin<Item, String, Object> photo = item.join(Item_.photos);
q.multiselect(item.get(Item_.name), photo)
.where(cb.like(photo.key(), "%egret%"));
This query is equivalent to the following Java Persistence query language query:
SELECT i.name, p
FROM Item i JOIN i.photos p
WHERE KEY(p) LIKE ‘%egret%’
6.5.6 Restricting the Query Result
The result of a query can be restricted by specifying one or more predicate conditions. Restriction predicates are applied to the CriteriaQuery object by means of the where method. Invocation of the
where method results in the modification of the CriteriaQuery object with the specified restriction(s).
The argument to the where method can be either an Expression<Boolean> instance or zero or
more Predicate instances. A predicate can be either simple or compound.
A simple predicate is created by invoking one of the conditional methods of the CriteriaBuilder
interface, or by the isNull, isNotNull, and in methods of the Expression interface. The
semantics of the conditional methods—e.g., equal, notEqual, gt, ge, lt, le, between, and
like— mirror those of the corresponding Java Persistence query language operators as described in
Chapter 4.
4/2/13
312
JSR-338 Final Release
Oracle
Constructing Criteria Queries
Java Persistence 2.1, Final Release
Criteria API
Compound predicates are constructed by means of the and, or, and not methods of the CriteriaBuilder interface.
The restrictions upon the types to which conditional operations are permitted to be applied are the same
as the respective operators of the Java Persistence query language as described in subsections 4.6.7
through 4.6.17. The same null value semantics as described in section 4.11 and the subsections of section 4.6 apply. The equality and comparison semantics described in section 4.12 likewise apply.
Example 1:
CriteriaQuery<TransactionHistory> q =
cb.createQuery(TransactionHistory.class);
Root<CreditCard> cc = q.from(CreditCard.class);
ListJoin<CreditCard,TransactionHistory> t =
cc.join(CreditCard_.transactionHistory);
q.select(t)
.where(cb.equal(cc.get(CreditCard_.customer)
.get(Customer_.accountNum),
321987),
cb.between (t.index(), 0, 9));
This query is equivalent to the following Java Persistence query language query:
SELECT t
FROM CreditCard c JOIN c.transactionHistory t
WHERE c.customer.accountNum = 321987 AND INDEX(t) BETWEEN 0 AND 9
Example 2:
CriteriaQuery<Order> q = cb.createQuery(Order.class);
Root<Order> order = q.from(Order.class);
q.where(cb.isEmpty(order.get(Order_.lineItems)))
.select(order);
This query is equivalent to the following Java Persistence query language query:
SELECT o
FROM Order o
WHERE o.lineItems IS EMPTY
6.5.7 Downcasting
Downcasting by means of the treat method is supported in joins and in the construction of where
conditions.
Example 1:
CriteriaQuery<String> q = cb.createQuery(String.class);
Root<Order> order = q.from(Order.class);
Join<Order,Book> book =
cb.treat(order.join(Order_.product), Book.class);
q.select(book.get(Book_.isbn));
JSR-338 Final Release
313
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Constructing Criteria Queries
This query is equivalent to the following Java Persistence query language query.
SELECT b.ISBN
FROM Order o JOIN TREAT(o.product AS Book) b
Example 2:
CriteriaQuery<Customer> q = cb.createQuery(Customer.class);
Root<Customer> customer = q.from(Customer.class);
Join<Customer, Order> order = customer.join(Customer_.orders);
q.where(cb.equal(cb.treat(order.get(Order_.product), Book.class)
.get(Book_.name),
"Iliad"));
q.select(customer);
This query is equivalent to the following Java Persistence query language query:
SELECT c
FROM Customer c JOIN c.orders o
WHERE TREAT(o.product AS Book).name = 'Iliad'
Example 3:
CriteriaQuery<Employee> q = cb.createQuery(Employee.class);
Root<Employee> e = q.from(Employee.class);
q.where(
cb.or(cb.gt(cb.treat(e, Exempt.class).get(Exempt_.vacationDays),
10),
cb.gt(cb.treat(e, Contractor.class).get(Contractor_.hours),
100)));
This query is equivalent to the following Java Persistence query language query:
SELECT e
FROM Employee e
WHERE TREAT(e AS Exempt).vacationDays > 10
OR TREAT(e AS Contractor).hours > 100
6.5.8 Expressions
An Expression or one of its subtypes can be used in the construction of the query’s select list or in
the construction of where or having method conditions.
Paths and boolean predicates are expressions.
Other expressions are created by means of the methods of the CriteriaBuilder interface. The
CriteriaBuilder interface provides methods corresponding to the built-in arthmetic, string,
datetime, and case operators and functions of the Java Persistence query language.
4/2/13
314
JSR-338 Final Release
Oracle
Constructing Criteria Queries
Java Persistence 2.1, Final Release
Criteria API
Example 1:
CriteriaQuery<Tuple> q = cb.createTupleQuery();
Root<Customer> cust = q.from(Customer.class);
Join<Customer, Order> order = cust.join(Customer_.orders);
Join<Customer, Address> addr = cust.join(Customer_.address);
q.where(cb.equal(addr.get(Address_.state), "CA"),
cb.equal(addr.get(Address_.county), "Santa Clara"));
q.multiselect(order.get(Order_.quantity),
cb.prod(order.get(Order_.totalCost), 1.08),
addr.get(Address_.zipcode));
The following Java Persistence query language query is equivalent:
SELECT o.quantity, o.totalCost*1.08, a.zipcode
FROM Customer c JOIN c.orders o JOIN c.address a
WHERE a.state = 'CA’ AND a.county = 'Santa Clara’
Example 2:
CriteriaQuery<Employee> q = cb.createQuery(Employee.class);
Root<Employee> emp = q.from(Employee.class);
q.select(emp)
.where(cb.notEqual(emp.type(), Exempt.class));
The type method can only be applied to a path expression. Its result denotes the type navigated to by
the path.
The following Java Persistence query language query is equivalent:
SELECT e
FROM Employee e
WHERE TYPE(e) <> Exempt
Example 3:
CriteriaQuery<String> q = cb.createQuery(String.class);
Root<Course> c = q.from(Course.class);
ListJoin<Course, Student> w = c.join(Course_.studentWaitlist);
q.where(cb.equal(c.get(Course_.name), "Calculus"),
cb.equal(w.index(), 0))
.select(w.get(Student_.name));
The index method can be applied to a ListJoin object that corresponds to a list for which an order
column has been specified. Its result denotes the position of the item in the list.
The following Java Persistence query language query is equivalent:
SELECT w.name
FROM Course c JOIN c.studentWaitlist w
WHERE c.name = 'Calculus’
AND INDEX(w) = 0
JSR-338 Final Release
315
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Constructing Criteria Queries
Example 4:
CriteriaQuery<BigDecimal> q = cb.createQuery(BigDecimal.class);
Root<Order> order = q.from(Order.class);
Join<Order, Item> item = order.join(Order_.lineItems);
Join<Order, Customer> cust = order.join(Order_.customer);
q.where(cb.equal(cust.get(Customer_.lastName), "Smith"),
cb.equal(cust.get(Customer_.firstName), "John"));
q.select(cb.sum(item.get(Item_.price)));
The aggregation methods avg, max, min, sum, count can only be used in the construction of the
select list or in having method conditions.
The following Java Persistence query language query is equivalent:
SELECT SUM(i.price)
FROM Order o JOIN o.lineItems i JOIN o.customer c
WHERE c.lastName = 'Smith’ AND c.firstName = 'John’
Example 5:
CriteriaQuery<Integer> q = cb.createQuery(Integer.class);
Root<Department> d = q.from(Department.class);
q.where(cb.equal(d.get(Department_.name), "Sales"))
.select(cb.size(d.get(Department_.employees)));
The size method can be applied to a path expression that corresponds to an association or element collection. Its result denotes the number of elements in the association or element collection.
The following Java Persistence query language query is equivalent:
SELECT SIZE(d.employees)
FROM Department d
WHERE d.name = ‘Sales’
Example 6:
Both simple and general case expressions are supported. The query below illustrates use of a general
case expression.
CriteriaQuery<Tuple> q = cb.createTupleQuery();
Root<Employee> e = q.from(Employee.class);
q.where(cb.equal(e.get(Employee_.department).get(Department_.name),
"Engineering"));
q.multiselect(e.get(Employee_.name),
cb.selectCase()
.when(cb.equal(e.get(Employee_.rating), 1),
cb.prod(e.get(Employee_.salary), 1.1))
.when(cb.equal(e.get(Employee_.rating), 2),
cb.prod(e.get(Employee_.salary), 1.2))
.otherwise(cb.prod(e.get(Employee_.salary), 1.01)));
4/2/13
316
JSR-338 Final Release
Oracle
Constructing Criteria Queries
Java Persistence 2.1, Final Release
Criteria API
The following Java Persistence query language query is equivalent:
SELECT e.name,
CASE WHEN e.rating
WHEN e.rating
ELSE e.salary
END
FROM EMPLOYEE e
WHERE e.department.name =
= 1 THEN e.salary * 1.1
= 2 THEN e.salary * 1.2
* 1.01
‘Engineering’
6.5.8.1 Result Types of Expressions
The getJavaType method, as defined in the TupleElement interface, returns the runtime type of
the object on which it is invoked.
In the case of the In, Case, SimpleCase, and Coalesce builder interfaces, the runtime results of
the getJavaType method may differ from the Expression type and may vary as the expression is
incrementally constructed. For non-numerical operands, the implementation must return the most specific common superclass of the types of the operands used to form the result.
In the case of the two-argument sum, prod, diff, quot, coalesce, and nullif methods, and the
In, Case, SimpleCase, and Coalesce builder methods, the runtime result types will differ from
the Expression type when the latter is Number. The following rules must be observed by the implementation when materializing the results of numeric expressions involving these methods. These rules
correspond to those specified for the Java Persistence query language as defined in section 4.8.6.
• If there is an operand of type Double, the result of the operation is of type Double;
• otherwise, if there is an operand of type Float, the result of the operation is of type Float;
• otherwise, if there is an operand of type BigDecimal, the result of the operation is of type BigDecimal;
• otherwise, if there is an operand of type BigInteger, the result of the operation is of type BigInteger, unless the method is quot, in which case the numeric result type is not further defined;
• otherwise, if there is an operand of type Long, the result of the operation is of type Long,
unless the method is quot, in which case the numeric result type is not further defined;
• otherwise, if there is an operand of integral type, the result of the operation is of type Integer,
unless the method is quot, in which case the numeric result type is not further defined.
Users should note that the semantics of the SQL division operation are not standard across
databases. In particular, when both operands are of integral types, the result of the division
operation will be an integral type in some databases, and an non-integral type in others. Portable applications should not assume a particular result type.
JSR-338 Final Release
317
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Constructing Criteria Queries
6.5.9 Literals
An Expression literal instance is obtained by passing a value to the literal method of the CriteriaBuilder interface. An Expression instance representing a null is created by the
nullLiteral method of the CriteriaBuilder interface.
Example:
CriteriaQuery<String> q = cb.createQuery(String.class);
Root<Employee> emp = q.from(Employee.class);
Join<Employee, FrequentFlierPlan> fp =
emp.join(Employee_.frequentFlierPlan);
q.select(cb.<String>selectCase()
.when(cb.gt(fp.get(FrequentFlierPlan_.annualMiles),
50000),
cb.literal("Platinum"))
.when(cb.gt(fp.get(FrequentFlierPlan_.annualMiles),
25000),
cb.literal("Silver"))
.otherwise(cb.nullLiteral(String.class)));
The following Java Persistence query language query is equivalent:
SELECT CASE WHEN fp.annualMiles > 50000 THEN 'Platinum'
WHEN fp.annualMiles > 25000 THEN 'Gold'
ELSE NULL
END
6.5.10 Parameter Expressions
A ParameterExpression instance is an expression that corresponds to a parameter whose value
will be supplied before the query is executed. Parameter expressions can only be used in the construction of conditional predicates.
Example:
CriteriaQuery<Customer> q = cb.createQuery(Customer.class);
Root<Customer> c = q.from(Customer.class);
ParameterExpression<Integer> param = cb.parameter(Integer.class);
q.select(c).where(cb.equal(c.get(Customer_.status), param));
If a name is supplied when the ParameterExpression instance is created, the parameter may also
be treated as a named parameter when the query is executed:
CriteriaQuery<Customer> q = cb.createQuery(Customer.class);
Root<Customer> c = q.from(Customer.class);
ParameterExpression<Integer> param =
cb.parameter(Integer.class, "stat");
q.select(c).where(cb.equal(c.get(Customer_.status), param));
4/2/13
318
JSR-338 Final Release
Oracle
Constructing Criteria Queries
Java Persistence 2.1, Final Release
Criteria API
This is equivalent to the following query in the Java Persistence query language:
SELECT c
FROM Customer c
WHERE c.status = :stat
6.5.11 Specifying the Select List
The select list of a query is specified by use of the select or multiselect methods of the CriteriaQuery interface. The arguments to the select and multiselect methods are Selection
instances.
Portable applications should use the select or multiselect method to specify the
query’s selection list. Applications that do not use one of these methods will not be portable.
The select method takes a single Selection argument, which can be either an Expression
instance or a CompoundSelection instance. The type of the Selection item must be assignable
to the defined CriteriaQuery result type, as described in section 6.5.1.
The construct, tuple and array methods of the CriteriaBuilder interface are used to
aggregate multiple selection items into a CompoundSelection instance.
The multiselect method also supports the specification and aggregation of multiple selection
items. When the multiselect method is used, the aggregation of the selection items is determined
by the result type of the CriteriaQuery object as described in sections 6.5.1 and 6.3.4.
A Selection instance passed to the construct, tuple, array, or multiselect methods can
be one of the following:
• An Expression instance.
• A Selection instance obtained as the result of the invocation of the CriteriaBuilder
construct method.
The distinct method of the CriteriaQuery interface is used to specify that duplicate values
must be eliminated from the query result. If the distinct method is not used or distinct(false) is invoked on the criteria query object, duplicate values are not eliminated. When
distinct(true) is used, and the select items include embeddable objects or map entry results, the
elimination of duplicates is undefined.
The semantics of the construct method used in the selection list is as described in section 4.8.2. The
semantics of embeddables returned by the selection list are as described in section 4.8.4.
Example 1:
In the following example, videoInventory is a Map from the entity Movie to the number of copies
in stock.
JSR-338 Final Release
319
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Constructing Criteria Queries
CriteriaQuery<Tuple> q = cb.createTupleQuery();
Root<VideoStore> v = q.from(VideoStore.class);
MapJoin<VideoStore, Movie, Integer> inv =
v.join(VideoStore_.videoInventory);
q.multiselect(v.get(VideoStore_.location).get(Address_.street),
inv.key().get(Movie_.title),
inv);
q.where(cb.equal(v.get(VideoStore_.location).get(Address_.zipcode),
"94301"),
cb.gt(inv, 0));
This query is equivalent to the following, in which the tuple method is used:
CriteriaQuery<Tuple> q = cb.createTupleQuery();
Root<VideoStore> v = q.from(VideoStore.class);
MapJoin<VideoStore, Movie, Integer> inv =
v.join(VideoStore_.videoInventory);
q.select(cb.tuple(v.get(VideoStore_.location).get(Address_.street),
inv.key().get(Movie_.title),
inv));
q.where(cb.equal(v.get(VideoStore_.location).get(Address_.zipcode),
"94301"),
cb.gt(inv, 0));
Both are equivalent to the following Java Persistence query language query:
SELECT v.location.street, KEY(i).title, VALUE(i)
FROM VideoStore v JOIN v.videoInventory i
WHERE v.location.zipcode = '94301' AND VALUE(i) > 0
Example 2:
The following two queries are equivalent to the Java Persistence query language query above. Because
the result type is not specified by the createQuery method, an Object[] is returned as a result of
the query execution:
CriteriaQuery<Object> q = cb.createQuery();
Root<VideoStore> v = q.from(VideoStore.class);
MapJoin<VideoStore, Movie, Integer> inv =
v.join(VideoStore_.videoInventory);
q.multiselect(v.get(VideoStore_.location).get(Address_.street),
inv.key().get(Movie_.title),
inv);
q.where(cb.equal(v.get(VideoStore_.location).get(Address_.zipcode),
"94301"),
cb.gt(inv, 0));
Equivalently:
CriteriaQuery<Object> q = cb.createQuery();
Root<VideoStore> v = q.from(VideoStore.class);
MapJoin<VideoStore, Movie, Integer> inv =
v.join(VideoStore_.videoInventory);
q.select(cb.array(v.get(VideoStore_.location).get(Address_.street),
inv.key().get(Movie_.title),
4/2/13
320
JSR-338 Final Release
Oracle
Constructing Criteria Queries
Java Persistence 2.1, Final Release
Criteria API
inv));
q.where(cb.equal(v.get(VideoStore_.location).get(Address_.zipcode),
"94301"),
cb.gt(inv, 0));
Example 3:
The following example illustrates the specification of a constructor.
CriteriaQuery<CustomerDetails> q =
cb.createQuery(CustomerDetails.class);
Root<Customer> c = q.from(Customer.class);
Join<Customer, Order> o = c.join(Customer_.orders);
q.where(cb.gt(o.get(Order_.quantity), 100));
q.select(cb.construct(CustomerDetails.class,
c.get(Customer_.id),
c.get(Customer_.status),
o.get(Order_.quantity)));
The following Java Persistence query language query is equivalent:
SELECT NEW com.acme.example.CustomerDetails(c.id, c.status, o.quantity)
FROM Customer c JOIN c.orders o
WHERE o.quantity > 100
6.5.11.1 Assigning Aliases to Selection Items
The alias method of the Selection interface can be used to assign an alias to a selection item. The
alias may then later be used to extract the corresponding item from the query result when the query is
executed. The alias method assigns the given alias to the Selection item. Once assigned, the alias
cannot be changed.
Example:
CriteriaQuery<Tuple> q = cb.createTupleQuery();
Root<Customer> c = q.from(Customer.class);
Join<Customer, Order> o = c.join(Customer_.orders);
Join<Customer, Address> a = c.join(Customer_.address);
q.where(cb.equal(c.get(Customer_.id), 97510));
q.multiselect(o.get(Order_.quantity).alias("quantity"),
cb.prod(o.get(Order_.totalCost), 1.08)
.alias("taxedCost"),
a.get(Address_.zipcode).alias("zipcode"));
TypedQuery<Tuple> typedQuery = em.createQuery(q);
Tuple result = typedQuery.getSingleResult();
Double cost = (Double) result.get("taxedCost");
6.5.12 Subqueries
Both correlated and non-correlated subqueries can be used in restriction predicates. A subquery is constructed through the creation and modification of a Subquery object.
JSR-338 Final Release
321
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Constructing Criteria Queries
A Subquery instance can be passed as an argument to the all, any, or some methods of the CriteriaBuilder interface for use in conditional expressions.
A Subquery instance can be passed to the CriteriaBuilder exists method to create a conditional predicate.
Example 1: Non-correlated subquery
The query below contains a non-correlated subquery. A non-correlated subquery does not reference
objects of the query of which it is a subquery. In particular, Root, Join, and Path instances are not
shared between the subquery and the criteria query instance of which it is a subquery.
// create criteria query instance, with root Customer
CriteriaQuery<Customer> q = cb.createQuery(Customer.class);
Root<Customer> goodCustomer = q.from(Customer.class);
// create subquery instance, with root Customer
// the Subquery object is typed according to its return type
Subquery<Double> sq = q.subquery(Double.class);
Root<Customer> customer = sq.from(Customer.class);
// the result of the first query depends on the subquery
q.where(cb.lt(
goodCustomer.get(Customer_.balanceOwed),
sq.select(cb.avg(customer.get(Customer_.balanceOwed)))));
q.select(goodCustomer);
This query corresponds to the following Java Persistence query language query.
SELECT goodCustomer
FROM Customer goodCustomer
WHERE goodCustomer.balanceOwed < (
SELECT AVG(c.balanceOwed) FROM Customer c)
Example 2: Correlated subquery
// create CriteriaQuery instance, with root Employee
CriteriaQuery<Employee> q = cb.createQuery(Employee.class);
Root<Employee> emp = q.from(Employee.class);
// create Subquery instance, with root Employee
Subquery<Employee> sq = q.subquery(Employee.class);
Root<Employee> spouseEmp = sq.from(Employee.class);
// the subquery references the root of the containing query
sq.where(cb.equal(spouseEmp, emp.get(Employee_.spouse)))
.select(spouseEmp);
// an exists condition is applied to the subquery result:
q.where(cb.exists(sq));
q.select(emp).distinct(true);
4/2/13
322
JSR-338 Final Release
Oracle
Constructing Criteria Queries
Java Persistence 2.1, Final Release
Criteria API
The above query corresponds to the following Java Persistence query language query.
SELECT DISTINCT emp
FROM Employee emp
WHERE EXISTS (
SELECT spouseEmp
FROM Employee spouseEmp
WHERE spouseEmp = emp.spouse)
Example 3: Subquery qualified by all()
// create CriteriaQuery instance, with root Employee
CriteriaQuery<Employee> q = cb.createQuery(Employee.class);
Root<Employee> emp = q.from(Employee.class);
// create Subquery instance, with root Manager
Subquery<BigDecimal> sq = q.subquery(BigDecimal.class);
Root<Manager> manager = sq.from(Manager.class);
sq.select(manager.get(Manager_.salary));
sq.where(cb.equal(manager.get(Manager_.department),
emp.get(Employee_.department)));
// an all expression is applied to the subquery result
q.select(emp)
.where(cb.gt(emp.get(Employee_.salary), cb.all(sq)));
This query corresponds to the following Java Persistence query language query:
SELECT emp
FROM Employee emp
WHERE emp.salary > ALL (
SELECT m.salary
FROM Manager m
WHERE m.department = emp.department)
Example 4: A Special case
In order to express some correlated subqueries involving unidirectional relationships, it may be useful
to correlate the domain of the subquery with the domain of the containing query. This is performed by
using the correlate method of the Subquery interface.
For example:
CriteriaQuery<Customer> q = cb.createQuery(Customer.class);
Root<Customer> customer = q.from(Customer.class);
Subquery<Long> sq = q.subquery(Long.class);
Root<Customer> customerSub = sq.correlate(customer);
Join<Customer,Order> order = customerSub.join(Customer_.orders);
q.where(cb.gt(sq.select(cb.count(order)), 10))
.select(customer);
JSR-338 Final Release
323
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Constructing Criteria Queries
This query corresponds to the following Java Persistence query language query:
SELECT c
FROM Customer c
WHERE (SELECT COUNT(o) FROM c.orders o) > 10
Note that joins involving the derived subquery root do not affect the join conditions of the containing
query. The following two query definitions thus differ in semantics:
CriteriaQuery<Order> q = cb.createQuery(Order.class);
Root<Order> order = q.from(Order.class);
Subquery<Integer> sq = q.subquery(Integer.class);
Root<Order> orderSub = sq.correlate(order);
Join<Order,Customer> customer = orderSub.join(Order_.customer);
Join<Customer,Account> account = customer.join(Customer_.accounts);
sq.select(account.get(Account_.balance));
q.where(cb.lt(cb.literal(10000), cb.all(sq)));
and
CriteriaQuery<Order> q = cb.createQuery(Order.class);
Root<Order> order = q.from(Order.class);
Join<Order,Customer> customer = order.join(Order_.customer);
Subquery<Integer> sq = q.subquery(Integer.class);
Join<Order,Customer> customerSub = sq.correlate(customer);
Join<Customer,Account> account =
customerSub.join(Customer_.accounts);
sq.select(account.get(Account_.balance));
q.where(cb.lt(cb.literal(10000), cb.all(sq)));
The first of these queries will return orders that are not associated with customers, whereas the second
will not. The corresponding Java Persistence query language queries are the following:
SELECT o
FROM Order o
WHERE 10000 < ALL (
SELECT a.balance
FROM o.customer c JOIN c.accounts a)
and
SELECT o
FROM Order o JOIN o.customer c
WHERE 10000 < ALL (
SELECT a.balance
FROM c.accounts a)
6.5.13 GroupBy and Having
The groupBy method of the CriteriaQuery interface is used to define a partitioning of the query
results into groups. The having method of the CriteriaQuery interface can be used to filter over
the groups.
The arguments to the groupBy method are Expression instances.
4/2/13
324
JSR-338 Final Release
Oracle
Constructing Criteria Queries
Java Persistence 2.1, Final Release
Criteria API
When the groupBy method is used, each selection item that is not the result of applying an aggregate
method must correspond to a path expression that is used for defining the grouping. Requirements on
the types that correspond to the elements of the grouping and having constructs and their relationship to
the select items are as specified in Section 4.7.
Example:
CriteriaQuery<Tuple> q = cb.createTupleQuery();
Root<Customer> customer = q.from(Customer.class);
q.groupBy(customer.get(Customer_.status));
q.having(cb.in(customer.get(Customer_.status)).value(1).value(2));
q.select(cb.tuple(
customer.get(Customer_.status),
cb.avg(customer.get(Customer_.filledOrderCount)),
cb.count(customer)));
This query is equivalent to the following Java Persistence query language query:
SELECT c.status, AVG(c.filledOrderCount), COUNT(c)
FROM Customer c
GROUP BY c.status
HAVING c.status IN (1, 2)
6.5.14 Ordering the Query Results
The ordering of the results of a query is defined by use of the orderBy method of the CriteriaQuery instance. The arguments to the orderBy method are Order instances.
An Order instance is created by means of the asc and desc methods of the CriteriaBuilder
interface. An argument to either of these methods must be one of the following:
• Any Expression instance that corresponds to an orderable state field of an entity or
embeddable class abstract schema type that is specified as an argument to the select or
multiselect method or that is an argument to a tuple or array constructor that is passed as
an argument to the select method.
• Any Expression instance that corresponds to the same state field of the same entity or
embeddable abstract schema type as an Expression instance that is specified as an argument to the select or multiselect method or that is an argument to a tuple or array constructor that is passed as an argument to the select method.
• An Expression instance that is specified as an argument to the select or multiselect
method or that is an argument to a tuple or array constructor that is passed as an argument to
the select method or that is semantically equivalent to such an Expression instance.
If more than one Order instance is specified, the order in which they appear in the argument list of the
orderBy method determines the precedence, whereby the first item has highest precedence.
SQL rules for the ordering of null values apply, as described in Section 4.9.
JSR-338 Final Release
325
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Constructing Criteria Queries
Example 1:
CriteriaQuery<Order> q = cb.createQuery(Order.class);
Root<Customer> c = q.from(Customer.class);
Join<Customer,Order> o = c.join(Customer_.orders);
Join<Customer,Address> a = c.join(Customer_.address);
q.where(cb.equal(a.get(Address_.state), "CA"));
q.select(o);
q.orderBy(cb.desc(o.get(Order_.quantity)),
cb.asc(o.get(Order_.totalCost)));
This query corresponds to the following Java Persistence query language query:
SELECT o
FROM Customer c JOIN c.orders o JOIN c.address a
WHERE a.state = 'CA’
ORDER BY o.quantity DESC, o.totalcost
Example 2:
CriteriaQuery<Tuple> q = cb.createTupleQuery();
Root<Customer> c = q.from(Customer.class);
Join<Customer, Order> o = c.join(Customer_.orders);
Join<Customer, Address> a = c.join(Customer_.address);
q.where(cb.equal(a.get(Address_.state), "CA"));
q.orderBy(cb.asc(o.get(Order_.quantity)),
cb.asc(a.get(Address_.zipcode)));
q.multiselect(o.get(Order_.quantity), a.get(Address_.zipcode));
This query corresponds to the following Java Persistence query language query:
SELECT o.quantity, a.zipcode
FROM Customer c JOIN c.orders o JOIN c.address a
WHERE a.state = 'CA’
ORDER BY o.quantity, a.zipcode
It can be equivalently expressed as follows:
CriteriaQuery<Tuple> q = cb.createTupleQuery();
Root<Customer> c = q.from(Customer.class);
Join<Customer, Order> o = c.join(Customer_.orders);
Join<Customer, Address> a = c.join(Customer_.address);
q.where(cb.equal(a.get(Address_.state), "CA"));
q.orderBy(cb.asc(o.get(Order_.quantity)),
cb.asc(a.get(Address_.zipcode)));
q.select(cb.tuple(o.get(Order_.quantity), a.get(Address_.zipcode)));
4/2/13
326
JSR-338 Final Release
Oracle
Constructing Criteria Queries
Java Persistence 2.1, Final Release
Criteria API
Example 3:
CriteriaQuery<Object[]> q = cb.createQuery(Object[].class);
Root<Customer> c = q.from(Customer.class);
Join<Customer, Order> o = c.join(Customer_.orders);
Join<Customer, Address> a = c.join(Customer_.address);
q.where(cb.equal(a.get(Address_.state), "CA"),
cb.equal(a.get(Address_.county), "Santa Clara"));
q.select(cb.array(o.get(Order_.quantity),
cb.prod(o.get(Order_.totalCost), 1.08),
a.get(Address_.zipcode)));
q.orderBy(cb.asc(o.get(Order_.quantity)),
cb.asc(cb.prod(o.get(Order_.totalCost), 1.08)),
cb.asc(a.get(Address_.zipcode)));
This query corresponds to the following Java Persistence query language query:
SELECT o.quantity, o.totalCost * 1.08 AS taxedCost, a.zipcode
FROM Customer c JOIN c.orders o JOIN c.address a
WHERE a.state = 'CA' AND a.county = 'Santa Clara'
ORDER BY o.quantity, taxedCost, a.zipcode
6.5.15 Bulk Update and Delete Operations
A bulk update query is constructed through the creation and modification of a javax.persistence.criteria.CriteriaUpdate object.
A CriteriaUpdate object is created by means of one of the createCriteriaUpdate methods
of the CriteriaBuilder interface. A CriteriaUpdate object is typed according to the entity
type that is the target of the update. A CriteriaUpdate object has a single root, the entity that is
being updated.
A bulk delete query is constructed through the creation and modification of a javax.persistence.criteria.CriteriaDelete object.
A CriteriaDelete object is created by means of one of the createCriteriaDelete methods
of the CriteriaBuilder interface. A CriteriaDelete object is typed according to the entity
type that is the target of the delete. A CriteriaDelete object has a single root, the entity that is
being deleted.
Example 1:
CriteriaUpdate<Customer> q = cb.createCriteriaUpdate(Customer.class);
Root<Customer> c = q.from(Customer.class);
q.set(c.get(Customer_.status), "outstanding")
.where(cb.lt(c.get(Customer_.balance), 10000));
The following Java Persistence query language update statement is equivalent.
UPDATE Customer c
SET c.status = 'outstanding'
WHERE c.balance < 10000
JSR-338 Final Release
327
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Constructing Criteria Queries
Example 2:
CriteriaUpdate<Employee> q = cb.createCriteriaUpdate(Employee.class);
Root<Employee> e = q.from(Employee.class);
q.set(e.get(Employee_.address).get(Address_.building), 22)
.where(cb.equal(e.get(Employee_.address).get(Address_.building),
14),
cb.equal(e.get(Employee_.address).get(Address_.city),
"Santa Clara"),
cb.equal(e.get(Employee_.project).get(Project_.name),
"Java EE"));
Address is an embeddable class. Note that updating across implicit joins is not supported.
The following Java Persistence query language update statement is equivalent.
UPDATE Employee e
SET e.address.building = 22
WHERE e.address.building = 14
AND e.address.city = 'Santa Clara'
AND e.project.name = 'Java EE'
Example 3:
The following update query causes multiple attributes to be updated.
CriteriaUpdate<Employee> q = cb.createCriteriaUpdate(Employee.class);
Root<Employee> e = q.from(Employee.class);
q.set(e.get(Employee_.salary),
cb.prod(e.get(Employee_.salary), 1.1f))
.set(e.get(Employee_.commission),
cb.prod(e.get(Employee_.commission), 1.1f))
.set(e.get(Employee_.bonus),
cb.sum(e.get(Employee_.bonus), 5000))
.where(cb.equal(e.get(Employee_.dept).get(Department_.name),
"Sales"));
The following Java Persistence query language update statement is equivalent.
UPDATE Employee e
SET e.salary = e.salary * 1.1,
e.commission = e.commission * 1.1,
e.bonus = e.bonus + 5000
WHERE e.dept.name = 'Sales'
Example 4:
CriteriaDelete<Customer> q = cb.createCriteriaDelete(Customer.class);
Root<Customer> c = q.from(Customer.class);
q.where(cb.equal(c.get(Customer_.status), "inactive"),
cb.isEmpty(c.get(Customer_.orders)));
4/2/13
328
JSR-338 Final Release
Oracle
Constructing Strongly-typed Queries using the javax.persistence.metamodel InterfacesJava Persistence 2.1, Final Release Criteria API
The following Java Persistence query language delete statement is equivalent.
DELETE
FROM Customer c
WHERE c.status = 'inactive'
AND c.orders IS EMPTY
Like bulk update and delete operations made through the Java Persistence query language, criteria API
bulk update and delete operations map directly to database operations, bypassing any optimistic locking
checks. Portable applications using bulk update operations must manually update the value of the version column, if desired, and/or manually validate the value of the version column.
The persistence context is not synchronized with the result of the bulk update or delete. See section
4.10.
6.6 Constructing Strongly-typed Queries using the
javax.persistence.metamodel Interfaces
Strongly-typed queries can also be constructed, either statically or dynamically, in the absence of generated metamodel classes. The javax.persistence.metamodel interfaces are used to access the
metamodel objects that correspond to the managed classes.
The following examples illustrate this approach. These are equivalent to the example queries shown in
section 6.5.5.
The Metamodel interface is obtained from the EntityManager or EntityManagerFactory for the persistence unit, and then used to obtain the corresponding metamodel objects for the managed types referenced by the queries.
JSR-338 Final Release
329
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release Use of the Criteria API with Strings to Reference
Example 1:
EntityManager em = ...;
Metamodel mm = em.getMetamodel();
EntityType<Employee> emp_ = mm.entity(Employee.class);
EmbeddableType<ContactInfo> cinfo_ =
mm.embeddable(ContactInfo.class);
EntityType<Phone> phone_ = mm.entity(Phone.class);
EmbeddableType<Address> addr_ = mm.embeddable(Address.class);
CriteriaQuery<Vendor> q = cb.createQuery(Vendor.class);
Root<Employee> emp = q.from(Employee.class);
Join<Employee, ContactInfo> cinfo =
emp.join(emp_.getSingularAttribute("contactInfo",
ContactInfo.class));
Join<ContactInfo, Phone> p =
cinfo.join(cinfo_.getSingularAttribute("phones", Phone.class));
q.where(
cb.equal(emp.get(emp_.getSingularAttribute("contactInfo",
ContactInfo.class))
.get(cinfo_.getSingularAttribute("address",
Address.class))
.get(addr_.getSingularAttribute("zipcode",
String.class)),
"95054"))
.select(p.get(phone_.getSingularAttribute("vendor",Vendor.class)));
Example 2:
EntityManager em = ...;
Metamodel mm = em.getMetamodel();
EntityType<Item> item_ = mm.entity(Item.class);
CriteriaQuery<Tuple> q = cb.createTupleQuery();
Root<Item> item = q.from(Item.class);
MapJoin<Item, String, Object> photo =
item.join(item_.getMap("photos", String.class, Object.class));
q.multiselect(
item.get(item_.getSingularAttribute("name", String.class)),
photo)
.where(cb.like(photo.key(), "%egret%"));
6.7 Use of the Criteria API with Strings to Reference Attributes
The Criteria API provides the option of specifying the attribute references used in joins and navigation
by attribute names used as arguments to the various join, fetch, and get methods.
The resulting queries have the same semantics as described in section 6.5, but do not provide the same
level of type safety.
The examples in this section illustrate this approach. These examples are derived from among those of
sections 6.5.3 and 6.5.5.
4/2/13
330
JSR-338 Final Release
Oracle
Use of the Criteria API with Strings to Reference AttributesJava Persistence 2.1, Final Release
Criteria API
Example 1:
CriteriaBuilder cb = ...
CriteriaQuery<String> q = cb.createQuery(String.class);
Root<Customer> cust = q.from(Customer.class);
Join<Order, Item> item =
cust.join("orders").join("lineItems");
q.select(cust.<String>get("name"))
.where(
cb.equal(item.get("product").get("productType"),
"printer"));
This query is equivalent to the following Java Persistence query language query:
SELECT c.name
FROM Customer c JOIN c.orders o JOIN o.lineItems i
WHERE i.product.productType = 'printer'
It is not required that type parameters be used. However, their omission may result in compiler warnings, as with the below version of the same query:
CriteriaBuilder cb = ...
CriteriaQuery q = cb.createQuery();
Root cust = q.from(Customer.class);
Join item = cust.join("orders").join("lineItems");
q.select(cust.get("name"))
.where(
cb.equal(item.get("product").get("productType"),
"printer"));
Example 2:
The following query uses an outer join:
CriteriaQuery<Customer> q = cb.createQuery(Customer.class);
Root<Customer> cust = q.from(Customer.class);
Join<Customer,Order> order =
cust.join("orders", JoinType.LEFT);
q.where(cb.equal(cust.get("status"), 1))
.select(cust);
This query is equivalent to the following Java Persistence query language query:
SELECT c FROM Customer c LEFT JOIN c.orders o WHERE c.status = 1
Example 3:
In the following example, ContactInfo is an embeddable class consisting of an address and set of
phones. Phone is an entity.
JSR-338 Final Release
331
4/2/13
Oracle
Criteria API
Java Persistence 2.1, Final Release
Query Modification
CriteriaQuery<Vendor> q = cb.createQuery(Vendor.class);
Root<Employee> emp = q.from(Employee.class);
Join<ContactInfo, Phone> phone =
emp.join("contactInfo").join("phones");
q.where(cb.equal(emp.get("contactInfo")
.get("address")
.get("zipcode"),
"95054"));
q.select(phone.<Vendor>get("vendor"));
The following Java Persistence query language query is equivalent:
SELECT p.vendor
FROM Employee e JOIN e.contactInfo.phones p
WHERE e.contactInfo.address.zipcode = '95054'
Example 4:
In this example, the photos attribute corresponds to a map from photo label to filename. The map key
is a string, the value an object.
CriteriaQuery<Object> q = cb.createQuery();
Root<Item> item = q.from(Item.class);
MapJoin<Item, String, Object> photo = item.joinMap("photos");
q.multiselect(item.get("name"), photo)
.where(cb.like(photo.key(), "%egret%"));
This query is equivalent to the following Java Persistence query language query:
SELECT i.name, p
FROM Item i JOIN i.photos p
WHERE KEY(p) LIKE ’%egret%’
6.8 Query Modification
A CriteriaQuery, CriteriaUpdate, or CriteriaDelete object may be modified, either
before or after Query or TypedQuery objects have been created and executed from it. For example,
such modification may entail replacement of the where predicate or the select list. Modifications
may thus result in the same query object “base” being reused for several query instances.
For example, the user might create and execute a query from the following CriteriaQuery object:
CriteriaQuery<Customer> q = cb.createQuery(Customer.class);
Root<Customer> c = q.from(Customer.class);
Predicate pred =
cb.equal(c.get(Customer_.address).get(Address_.city),"Chicago");
q.select(c);
q.where(pred);
4/2/13
332
JSR-338 Final Release
Oracle
Query Execution
Java Persistence 2.1, Final Release
Criteria API
The CriteriaQuery object might then be modified to reflect a different predicate condition, for
example:
Predicate pred2 =
cb.gt(c.get(Customer_.balanceOwed), 1000);
q.where(pred2);
Note, however, that query elements—-in this example, predicate conditions—are dependent on the
CriteriaQuery, CriteriaUpdate, or CriteriaDelete instance, and are thus not portably
reusable with different instances.
6.9 Query Execution
A criteria query is executed by passing the CriteriaQuery, CriteriaUpdate, or CriteriaDelete object to the createQuery method of the EntityManager interface to create an executable TypedQuery object (or, in the case of CriteriaUpdate and CriteriaDelete, a Query
object), which can then be passed to one of the query execution methods of the TypedQuery or
Query interface.
A CriteriaQuery, CriteriaUpdate, or CriteriaDelete object may be further modified
after an executable query object has been created from it. The modification of the CriteriaQuery,
CriteriaUpdate, or CriteriaDelete object does not have any impact on the already created
executable query object. If the modified CriteriaQuery, CriteriaUpdate, or CriteriaDelete object is passed to the createQuery method, the persistence provider must insure that a new
executable query object is created and returned that reflects the semantics of the changed query definition.
CriteriaQuery, CriteriaUpdate, and CriteriaDelete objects must be serializable. A persistence vendor is required to support the subsequent deserialization of such an object into a separate
JVM instance of that vendor’s runtime, where both runtime instances have access to any required vendor implementation classes. CriteriaQuery, CriteriaUpdate, and CriteriaDelete
objects are not required to be interoperable across vendors.
JSR-338 Final Release
333
4/2/13
Oracle
Criteria API
4/2/13
Java Persistence 2.1, Final Release
334
Query Execution
JSR-338 Final Release
Oracle
Persistence Contexts
Ch apt er 7
Java Persistence 2.1, Final Release
Entity Managers and Persistence Contexts
Entity Managers and Persistence Contexts
7.1 Persistence Contexts
A persistence context is a set of managed entity instances in which for any persistent entity identity
there is a unique entity instance. Within the persistence context, the entity instances and their lifecycle
are managed by the entity manager.
In Java EE environments, a JTA transaction typically involves calls across multiple components. Such
components may often need to access the same persistence context within a single transaction. To facilitate such use of entity managers in Java EE environments, when an entity manager is injected into a
component or looked up directly in the JNDI naming context, its persistence context will automatically
be propagated with the current JTA transaction, and the EntityManager references that are mapped to
the same persistence unit will provide access to this same persistence context within the JTA transaction. This propagation of persistence contexts by the Java EE container avoids the need for the application to pass references to EntityManager instances from one component to another. An entity manager
for which the container manages the persistence context in this manner is termed a container-managed
entity manager. A container-managed entity manager’s lifecycle is managed by the Java EE container.
JSR-338 Final Release
335
4/2/13
Oracle
Entity Managers and Persistence Contexts
Java Persistence 2.1, Final Release
Obtaining an EntityManager
In less common use cases within Java EE environments, applications may need to access a persistence
context that is “stand-alone”—i.e. not propagated along with the JTA transaction across the EntityManager references for the given persistence unit. Instead, each instance of creating an entity manager
causes a new isolated persistence context to be created that is not accessible through other EntityManager references within the same transaction. These use cases are supported through the createEntityManager methods of the EntityManagerFactory interface. An entity manager that is used by
the application to create and destroy a persistence context in this manner is termed an application-managed entity manager. An application-managed entity manager’s lifecycle is managed by the application.
Both container-managed entity managers and application-managed entity managers and their persistence contexts are required to be supported in Java EE web containers and EJB containers. Within an
EJB environment, container-managed entity managers are typically used.
In Java SE environments and in Java EE application client containers, only application-managed entity
managers are required to be supported[79].
7.2 Obtaining an EntityManager
The entity manager for a persistence context is obtained from an entity manager factory.
When container-managed entity managers are used (in Java EE environments), the application does not
interact with the entity manager factory. The entity managers are obtained directly through dependency
injection or from JNDI, and the container manages interaction with the entity manager factory transparently to the application.
When application-managed entity managers are used, the application must use the entity manager factory to manage the entity manager and persistence context lifecycle.
An entity manager must not be shared among multiple concurrently executing threads, as the entity
manager and persistence context are not required to be threadsafe. Entity managers must only be
accessed in a single-threaded manner.
7.2.1 Obtaining an Entity Manager in the Java EE Environment
A container-managed entity manager is obtained by the application through dependency injection or
through direct lookup of the entity manager in the JNDI namespace. The container manages the persistence context lifecycle and the creation and the closing of the entity manager instance transparently to
the application.
[79] Note that the use of JTA is not required to be supported in application client containers.
4/2/13
336
JSR-338 Final Release
Oracle
Obtaining an Entity Manager Factory
Java Persistence 2.1, Final Release
Entity Managers and Persistence Contexts
The PersistenceContext annotation is used for entity manager injection. The type element
specifies whether a transaction-scoped or extended persistence context is to be used, as described in section 7.6. The synchronization element specifies whether the persistence context is always automatically joined to the current transaction (the default) or is not joined to the current transaction unless
the joinTransaction method is invoked by the application. The unitName element may optionally be specified to designate the persistence unit whose entity manager factory is used by the container.
The semantics of the persistence context synchronization type are further described in section 7.6.1.
Section 10.5.2 provides further information about the unitName element.
For example,
@PersistenceContext
EntityManager em;
@PersistenceContext(type=PersistenceContextType.EXTENDED)
EntityManager orderEM;
The JNDI lookup of an entity manager is illustrated below:
@Stateless
@PersistenceContext(name="OrderEM")
public class MySessionBean implements MyInterface {
@Resource SessionContext ctx;
}
public void doSomething() {
EntityManager em = (EntityManager)ctx.lookup("OrderEM");
...
}
7.2.2 Obtaining an Application-managed Entity Manager
An application-managed entity manager is obtained by the application from an entity manager factory.
The EntityManagerFactory API used to obtain an application-managed entity manager is the
same independent of whether this API is used in Java EE or Java SE environments.
7.3 Obtaining an Entity Manager Factory
The EntityManagerFactory interface is used by the application to create an application-managed
entity manager[80].
Each entity manager factory provides entity manager instances that are all configured in the same manner (e.g., configured to connect to the same database, use the same initial settings as defined by the
implementation, etc.)
[80] It may also be used internally by the Java EE container. See section 7.9.
JSR-338 Final Release
337
4/2/13
Oracle
Entity Managers and Persistence Contexts
Java Persistence 2.1, Final Release
EntityManagerFactory Interface
More than one entity manager factory instance may be available simultaneously in the JVM.[81]
Methods of the EntityManagerFactory interface are threadsafe.
7.3.1 Obtaining an Entity Manager Factory in a Java EE Container
Within a Java EE environment, an entity manager factory can be injected using the PersistenceUnit annotation or obtained through JNDI lookup. The unitName element may optionally be specified to designate the persistence unit whose entity manager factory is used. (See section 10.5.2).
For example,
@PersistenceUnit
EntityManagerFactory emf;
7.3.2 Obtaining an Entity Manager Factory in a Java SE Environment
Outside a Java EE container environment, the javax.persistence.Persistence class is the
bootstrap class that provides access to an entity manager factory. The application creates an entity manager factory by calling the createEntityManagerFactory method of the javax.persistence.Persistence class, described in section 9.7.
For example,
EntityManagerFactory emf =
javax.persistence.Persistence.createEntityManagerFactory("Order");
EntityManager em = emf.createEntityManager();
7.4 EntityManagerFactory Interface
The EntityManagerFactory interface is used by the application to obtain an application-managed
entity manager. When the application has finished using the entity manager factory, and/or at application shutdown, the application should close the entity manager factory. Once an entity manager factory
has been closed, all its entity managers are considered to be in the closed state.
The EntityManagerFactory interface provides access to information and services that are global
to the persistence unit. This includes access to the second level cache that is maintained by the persistence provider and to the PersistenceUnitUtil interface. The Cache interface is described in
section 7.10; the PersistenceUnitUtil interface in section 7.11.
[81] This may be the case when using multiple databases, since in a typical configuration a single entity manager only communicates
with a single database. There is only one entity manager factory per persistence unit, however.
4/2/13
338
JSR-338 Final Release
Oracle
EntityManagerFactory Interface
Java Persistence 2.1, Final Release
Entity Managers and Persistence Contexts
package javax.persistence;
import java.util.Map;
import javax.persistence.metamodel.Metamodel;
import javax.persistence.criteria.CriteriaBuilder;
/**
* Interface used to interact with the entity manager factory
* for the persistence unit.
*/
public interface EntityManagerFactory {
/**
* Create a new application-managed EntityManager.
* This method returns a new EntityManager instance each time
* it is invoked.
* The isOpen method will return true on the returned instance.
* @return entity manager instance
* @throws IllegalStateException if the entity manager factory
* has been closed
*/
public EntityManager createEntityManager();
/**
* Create a new application-managed EntityManager with the
* specified Map of properties.
* This method returns a new EntityManager instance each time
* it is invoked.
* The isOpen method will return true on the returned instance.
* @param map properties for entity manager
* @return entity manager instance
* @throws IllegalStateException if the entity manager factory
* has been closed
*/
public EntityManager createEntityManager(Map map);
/**
* Create a new JTA application-managed EntityManager with the
* specified synchronization type.
* This method returns a new EntityManager instance each time
* it is invoked.
* The isOpen method will return true on the returned instance.
* @param synchronizationType how and when the entity manager
* should be synchronized with the current JTA transaction
* @return entity manager instance
* @throws IllegalStateException if the entity manager factory
* has been configured for resource-local entity managers or has
* been closed
*/
public EntityManager createEntityManager(
SynchronizationType synchronizationType);
JSR-338 Final Release
339
4/2/13
Oracle
Entity Managers and Persistence Contexts
Java Persistence 2.1, Final Release
EntityManagerFactory Interface
/**
* Create a new JTA application-managed EntityManager with the
* specified synchronization type and Map of properties.
* This method returns a new EntityManager instance each time
* it is invoked.
* The isOpen method will return true on the returned instance.
* @param synchronizationType how and when the entity manager
* should be synchronized with the current JTA transaction
* @param map properties for entity manager; may be null
* @return entity manager instance
* @throws IllegalStateException if the entity manager factory
* has been configured for resource-local entity managers or has
* been closed
*/
public EntityManager createEntityManager(
SynchronizationType synchronizationType, Map map);
/**
* Return an instance of CriteriaBuilder for the creation of
* CriteriaQuery objects.
* @return CriteriaBuilder instance
* @throws IllegalStateException if the entity manager factory
* has been closed
*/
public CriteriaBuilder getCriteriaBuilder();
/**
* Return an instance of Metamodel interface for access to the
* metamodel of the persistence unit.
* @return Metamodel instance
* @throws IllegalStateException if the entity manager factory
* has been closed
*/
public Metamodel getMetamodel();
/**
* Indicates whether the factory is open. Returns true
* until the factory has been closed.
* @return boolean indicating whether the factory is open
*/
public boolean isOpen();
/**
* Close the factory, releasing any resources that it holds.
* After a factory instance has been closed, all methods invoked
* on it will throw the IllegalStateException, except for isOpen,
* which will return false. Once an EntityManagerFactory has
* been closed, all its entity managers are considered to be
* in the closed state.
* @throws IllegalStateException if the entity manager factory
* has been closed
*/
public void close();
4/2/13
340
JSR-338 Final Release
Oracle
EntityManagerFactory Interface
Java Persistence 2.1, Final Release
Entity Managers and Persistence Contexts
/**
* Get the properties and associated values that are in effect
* for the entity manager factory. Changing the contents of the
* map does not change the configuration in effect.
* @return properties
* @throws IllegalStateException if the entity manager factory
* has been closed
*/
public Map<String, Object> getProperties();
/**
* Access the cache that is associated with the entity manager
* factory (the "second level cache").
* @return instance of the Cache interface or null if no cache
* is in use
* @throws IllegalStateException if the entity manager factory
* has been closed
*/
public Cache getCache();
/**
* Return interface providing access to utility methods
* for the persistence unit.
* @return PersistenceUnitUtil interface
* @throws IllegalStateException if the entity manager factory
* has been closed
*/
public PersistenceUnitUtil getPersistenceUnitUtil();
/**
* Define the query, typed query, or stored procedure query as
* a named query such that future query objects can be created
* from it using the createNamedQuery or
* createNamedStoredProcedureQuery method.
* Any configuration of the query object (except for actual
* parameter binding) in effect when the named query is added
* is retained as part of the named query definition.
* This includes configuration information such as max results,
* hints, flush mode, lock mode, result set mapping information,
* and information about stored procedure parameters.
* When the query is executed, information that can be set
* by means of the query APIs can be overridden. Information
* that is overridden does not affect the named query as
* registered with the entity manager factory, and thus does
* not affect subsequent query objects created from it by
* means of the createNamedQuery or
* createNamedStoredProcedureQuery methods.
* If a named query of the same name has been previously
* defined, either statically via metadata or via this method,
* that query definition is replaced.
* @param name name for the query
* @param query Query, TypedQuery, or StoredProcedureQuery object
*/
public void addNamedQuery(String name, Query query);
JSR-338 Final Release
341
4/2/13
Oracle
Entity Managers and Persistence Contexts
Java Persistence 2.1, Final Release
Controlling Transactions
/**
* Return an object of the specified type to allow access to the
* provider-specific API. If the provider's EntityManagerFactory
* implementation does not support the specified class, the
* PersistenceException is thrown.
* @param cls the class of the object to be returned. This is
* normally either the underlying EntityManagerFactory
* implementation class or an interface that it implements.
* @return an instance of the specified class
* @throws PersistenceException if the provider does not
*
support the call
*/
public <T> T unwrap(Class<T> cls);
}
/**
* Add a named copy of the EntityGraph to the
* EntityManagerFactory. If an entity graph with the same name
* already exists, it is replaced.
* @param graphName name for the entity graph
* @param entityGraph entity graph
*/
public <T> void addNamedEntityGraph(String graphName,
EntityGraph<T> entityGraph);
Any number of vendor-specific properties may be included in the map passed to the createEntityManager methods. Properties that are not recognized by a vendor must be ignored.
Note that the policies of the installation environment may restrict some information from being made
available through the EntityManagerFactory getProperties method (for example, JDBC
user, password, URL).
Vendors should use vendor namespaces for properties (e.g., com.acme.persistence.logging).
Entries that make use of the namespace javax.persistence and its subnamespaces must not be
used for vendor-specific information. The namespace javax.persistence is reserved for use by
this specification.
7.5 Controlling Transactions
Depending on the transactional type of the entity manager, transactions involving EntityManager operations may be controlled either through JTA or through use of the resource-local EntityTransaction API, which is mapped to a resource transaction over the resource that underlies the entities
managed by the entity manager.
An entity manager whose underlying transactions are controlled through JTA is termed a JTA entity
manager.
An entity manager whose underlying transactions are controlled by the application through the
EntityTransaction API is termed a resource-local entity manager.
4/2/13
342
JSR-338 Final Release
Oracle
Controlling Transactions
Java Persistence 2.1, Final Release
Entity Managers and Persistence Contexts
A container-managed entity manager must be a JTA entity manager. JTA entity managers are only specified for use in Java EE containers.
An application-managed entity manager may be either a JTA entity manager or a resource-local entity
manager.
An entity manager is defined to be of a given transactional type—either JTA or resource-local—at the
time its underlying entity manager factory is configured and created. See sections 8.2.1.2 and 9.1.
Both JTA entity managers and resource-local entity managers are required to be supported in Java EE
web containers and EJB containers. Within an EJB environment, a JTA entity manager is typically used.
In general, in Java SE environments only resource-local entity managers are supported.
7.5.1 JTA EntityManagers
An entity manager whose transactions are controlled through JTA is a JTA entity manager. In general, a
JTA entity manager participates in the current JTA transaction, which is begun and committed external
to the entity manager and propagated to the underlying resource manager.
7.5.2 Resource-local EntityManagers
An entity manager whose transactions are controlled by the application through the EntityTransaction API is a resource-local entity manager. A resource-local entity manager transaction is mapped
to a resource transaction over the resource by the persistence provider. Resource-local entity managers
may use server or local resources to connect to the database and are unaware of the presence of JTA
transactions that may or may not be active.
7.5.3 The EntityTransaction Interface
The EntityTransaction interface is used to control resource transactions on resource-local entity
managers. The EntityManager.getTransaction() method returns an instance of the
EntityTransaction interface.
When a resource-local entity manager is used, and the persistence provider runtime throws an exception
defined to cause transaction rollback, the persistence provider must mark the transaction for rollback.
If the EntityTransaction.commit operation fails, the persistence provider must roll back the
transaction.
JSR-338 Final Release
343
4/2/13
Oracle
Entity Managers and Persistence Contexts
Java Persistence 2.1, Final Release
Controlling Transactions
package javax.persistence;
/**
* Interface used to control transactions on resource-local
* entity managers.
*/
public interface EntityTransaction {
/**
* Start a resource transaction.
* @throws IllegalStateException if isActive() is true
*/
public void begin();
/**
* Commit the current resource transaction, writing any
* unflushed changes to the database.
* @throws IllegalStateException if isActive() is false
* @throws RollbackException if the commit fails
*/
public void commit();
/**
* Roll back the current resource transaction.
* @throws IllegalStateException if isActive() is false
* @throws PersistenceException if an unexpected error
*
condition is encountered
*/
public void rollback();
/**
* Mark the current resource transaction so that the only
* possible outcome of the transaction is for the transaction
* to be rolled back.
* @throws IllegalStateException if isActive() is false
*/
public void setRollbackOnly();
/**
* Determine whether the current resource transaction has been
* marked for rollback.
* @return boolean indicating whether the transaction has been
*
marked for rollback
* @throws IllegalStateException if isActive() is false
*/
public boolean getRollbackOnly();
}
4/2/13
/**
* Indicate whether a resource transaction is in progress.
* @return boolean indicating whether transaction is
*
in progress
* @throws PersistenceException if an unexpected error
*
condition is encountered
*/
public boolean isActive();
344
JSR-338 Final Release
Oracle
Container-managed Persistence Contexts
Java Persistence 2.1, Final Release
Entity Managers and Persistence Contexts
7.5.4 Example
The following example illustrates the creation of an entity manager factory in a Java SE environment,
and its use in creating and using a resource-local entity manager.
import javax.persistence.*;
public class PasswordChanger {
public static void main (String[] args) {
EntityManagerFactory emf =
Persistence.createEntityManagerFactory("Order");
EntityManager em = emf.createEntityManager();
em.getTransaction().begin();
User user = (User)em.createQuery
("SELECT u FROM User u WHERE u.name=:name AND
u.pass=:pass")
.setParameter("name", args[0])
.setParameter("pass", args[1])
.getSingleResult();
if (user!=null)
user.setPassword(args[2]);
em.getTransaction().commit();
}
}
em.close();
emf.close();
7.6 Container-managed Persistence Contexts
When a container-managed entity manager is used, the lifecycle of the persistence context is always
managed automatically, transparently to the application, and the persistence context is propagated with
the JTA transaction.
A container-managed persistence context may be defined to have either a lifetime that is scoped to a single transaction or an extended lifetime that spans multiple transactions, depending on the PersistenceContextType that is specified when its entity manager is created. This specification refers to
such persistence contexts as transaction-scoped persistence contexts and extended persistence contexts
respectively.
The lifetime of the persistence context is declared using the PersistenceContext annotation or
the persistence-context-ref deployment descriptor element. By default, a transaction-scoped
persistence context is used.
Sections 7.6.2 and 7.6.3 describe transaction-scoped and extended persistence contexts in the absence of
persistence context propagation. Persistence context propagation is described in section 7.6.4.
JSR-338 Final Release
345
4/2/13
Oracle
Entity Managers and Persistence Contexts
Java Persistence 2.1, Final Release
Container-managed Persistence Contexts
Persistence contexts are always associated with an entity manager factory. In the following sections,
“the persistence context” should be understood to mean “the persistence context associated with a particular entity manager factory”.
7.6.1 Persistence Context Synchronization Type
By default, a container-managed persistence context is of type SynchronizationType.SYNCHRONIZED. Such a persistence context is automatically joined to the current JTA transaction, and
updates made to the persistence context are propagated to the underlying resource manager.
A container-managed persistence context may be specified to be of type SynchronizationType.UNSYNCHRONIZED. A persistence context of type SynchronizationType.UNSYNCHRONIZED is not enlisted in any JTA transaction unless explicitly joined to that transaction by the
application. A persistence context of type SynchronizationType.UNSYNCHRONIZED is enlisted
in a JTA transaction and registered for subsequent transaction notifications against that transaction by
the invocation of the EntityManager joinTransaction method. The persistence context
remains joined to the transaction until the transaction commits or rolls back. After the transaction commits or rolls back, the persistence context will not be joined to any subsequent transaction unless the
joinTransaction method is invoked in the scope of that subsequent transaction.
A persistence context of type SynchronizationType.UNSYNCHRONIZED must not be flushed to
the database unless it is joined to a transaction. The application's use of queries with pessimistic locks,
bulk update or delete queries, etc. result in the provider throwing the TransactionRequiredException. After the persistence context has been joined to the JTA transaction, these operations are
again allowed.
The application is permitted to invoke the persist, merge, remove, and refresh entity lifecycle operations
on an entity manager of type SynchronizationType.UNSYNCHRONIZED independent of
whether the persistence context is joined to the current transaction. After the persistence context has
been joined to a transaction, changes in a persistence context can be flushed to the database either
explicitly by the application or by the provider. If the flush method is not explicitly invoked, the persistence provider may defer flushing until commit time depending on the operations invoked and the
flush mode setting in effect.
If an extended persistence context of type SynchronizationType.UNSYNCHRONIZED has not
been joined to the current JTA transaction, rollback of the JTA transaction will have no effect upon the
persistence context. In general, it is recommended that a non-JTA datasource be specified for use by the
persistence provider for a persistence context of type SynchronizationType.UNSYNCHRONIZED that has not been joined to a JTA transaction in order to alleviate the risk of integrating uncommitted changes into the persistence context in the event that the transaction is later rolled back.
If a persistence context of type SynchronizationType.UNSYNCHRONIZED has been joined to
the JTA transaction, transaction rollback will cause the persistence context to be cleared and all
pre-existing managed and removed instances to become detached. (See section 3.3.3.)
When a JTA transaction exists, a persistence context of type SynchronizationType.UNSYNCHRONIZED is propagated with that transaction according to the rules in section 7.6.4.1 regardless of
whether the persistence context has been joined to that transaction.
4/2/13
346
JSR-338 Final Release
Oracle
Container-managed Persistence Contexts
Java Persistence 2.1, Final Release
Entity Managers and Persistence Contexts
7.6.2 Container-managed Transaction-scoped Persistence Context
The application can obtain a container-managed entity manager with transaction-scoped persistence
context by injection or direct lookup in the JNDI namespace. The persistence context type for the entity
manager is defaulted or defined as PersistenceContextType.TRANSACTION.
A new persistence context begins when the container-managed entity manager is invoked[82] in the
scope of an active JTA transaction, and there is no current persistence context already associated with
the JTA transaction. The persistence context is created and then associated with the JTA transaction.
This association of the persistence context with the JTA transaction is independent of the synchronization type of the persistence context and whether the persistence context has been joined to the transaction.
The persistence context ends when the associated JTA transaction commits or rolls back, and all entities
that were managed by the EntityManager become detached.[83]
If the entity manager is invoked outside the scope of a transaction, any entities loaded from the database
will immediately become detached at the end of the method call.
7.6.3 Container-managed Extended Persistence Context
A container-managed extended persistence context can only be initiated within the scope of a stateful
session bean. It exists from the point at which the stateful session bean that declares a dependency on an
entity manager of type PersistenceContextType.EXTENDED is created, and is said to be bound
to the stateful session bean. The dependency on the extended persistence context is declared by means
of the PersistenceContext annotation or persistence-context-ref deployment descriptor element. The association of the extended persistence context with the JTA transaction is independent
of the synchronization type of the persistence context and whether the persistence context has been
joined to the transaction.
The persistence context is closed by the container when the @Remove method of the stateful session
bean completes (or the stateful session bean instance is otherwise destroyed).
7.6.3.1 Inheritance of Extended Persistence Context
If a stateful session bean instantiates a stateful session bean (executing in the same EJB container
instance) which also has such an extended persistence context with the same synchronization type, the
extended persistence context of the first stateful session bean is inherited by the second stateful session
bean and bound to it, and this rule recursively applies—independently of whether transactions are active
or not at the point of the creation of the stateful session beans. If the stateful session beans differ in
declared synchronization type, the EJBException is thrown by the container.
If the persistence context has been inherited by any stateful session beans, the container does not close
the persistence context until all such stateful session beans have been removed or otherwise destroyed.
[82] Specifically, when one of the methods of the EntityManager interface is invoked.
[83] Note that this applies to a transaction-scoped persistence context of type SynchronizationType.UNSYNCHRONIZED that has not
been joined to the transaction as well.
JSR-338 Final Release
347
4/2/13
Oracle
Entity Managers and Persistence Contexts
Java Persistence 2.1, Final Release
Container-managed Persistence Contexts
7.6.4 Persistence Context Propagation
As described in section 7.1, a single persistence context may correspond to one or more JTA entity manager instances (all associated with the same entity manager factory[84]).
The persistence context is propagated across the entity manager instances as the JTA transaction is
propagated. A persistence context of type SynchronizationType.UNSYNCHRONIZED is propagated with the JTA transaction regardless of whether it has been joined to the transaction.
Propagation of persistence contexts only applies within a local environment. Persistence contexts are
not propagated to remote tiers.
7.6.4.1 Requirements for Persistence Context Propagation
Persistence contexts are propagated by the container across component invocations as follows.
If a component is called and there is no JTA transaction or the JTA transaction is not propagated, the
persistence context is not propagated.
• If an entity manager is then invoked from within the component:
• Invocation of an entity manager defined with PersistenceContext-
Type.TRANSACTION will result in use of a new persistence context (as described
in section 7.6.2).
• Invocation of an entity manager defined with PersistenceContext-
Type.EXTENDED will result in the use of the existing extended persistence context
bound to that component.
• If the entity manager is invoked within a JTA transaction, the persistence context will
be associated with the JTA transaction.
If a component is called and the JTA transaction is propagated into that component:
• If the component is a stateful session bean to which an extended persistence context has been
bound and there is a different persistence context associated with the JTA transaction, an
EJBException is thrown by the container.
• If there is a persistence context of type SynchronizationType.UNSYNCHRONIZED
associated with the JTA transaction and the target component specifies a persistence context of
type SynchronizationType.SYNCHRONIZED, the IllegalStateException is
thrown by the container.
• Otherwise, if there is a persistence context associated with the JTA transaction, that persistence
context is propagated and used.
[84] Entity manager instances obtained from different entity manager factories never share the same persistence context.
4/2/13
348
JSR-338 Final Release
Oracle
Container-managed Persistence Contexts
Java Persistence 2.1, Final Release
Entity Managers and Persistence Contexts
Note that a component with a persistence context of type SynchronizationType.UNSYNCHRONIZED may be called by a component propagating either a persistence
context of type SynchronizationType.UNSYNCHRONIZED or a persistence context of
type SynchronizationType.SYNCHRONIZED into it.
7.6.5 Examples
7.6.5.1 Container-managed Transaction-scoped Persistence Context
@Stateless
public class ShoppingCartImpl implements ShoppingCart {
@PersistenceContext EntityManager em;
public Order getOrder(Long id) {
Order order = em.find(Order.class, id);
order.getLineItems();
return order;
}
public Product getProduct(String name) {
return (Product) em.createQuery("select p from Product p
where p.name = :name")
.setParameter("name", name)
.getSingleResult();
}
public LineItem createLineItem(Order order, Product product, int
quantity) {
LineItem li = new LineItem(order, product, quantity);
order.getLineItems().add(li);
em.persist(li);
return li;
}
}
JSR-338 Final Release
349
4/2/13
Oracle
Entity Managers and Persistence Contexts
Java Persistence 2.1, Final Release
Container-managed Persistence Contexts
7.6.5.2 Container-managed Extended Persistence Context
/*
* An extended transaction context is used. The entities remain
* managed in the persistence context across multiple transactions.
*/
@Stateful
@Transaction(REQUIRES_NEW)
public class ShoppingCartImpl implements ShoppingCart {
@PersistenceContext(type=EXTENDED)
EntityManager em;
private Order order;
private Product product;
public void initOrder(Long id) {
order = em.find(Order.class, id);
}
public void initProduct(String name) {
product = (Product) em.createQuery("select p from Product p
where p.name = :name")
.setParameter("name", name)
.getSingleResult();
}
public LineItem createLineItem(int quantity) {
LineItem li = new LineItem(order, product, quantity);
order.getLineItems().add(li);
em.persist(li);
return li;
}
}
4/2/13
350
JSR-338 Final Release
Oracle
Application-managed Persistence Contexts
Java Persistence 2.1, Final Release
Entity Managers and Persistence Contexts
7.7 Application-managed Persistence Contexts
When an application-managed entity manager is used, the application interacts directly with the persistence provider's entity manager factory to manage the entity manager lifecycle and to obtain and destroy
persistence contexts.
All such application-managed persistence contexts are extended in scope, and can span multiple transactions.
The EntityManagerFactory.createEntityManager method and the EntityManager
close and isOpen methods are used to manage the lifecycle of an application-managed entity manager and its associated persistence context.
The extended persistence context exists from the point at which the entity manager has been created
using EntityManagerFactory.createEntityManager until the entity manager is closed by
means of EntityManager.close.
An extended persistence context obtained from the application-managed entity manager is a stand-alone
persistence context—it is not propagated with the transaction.
When a JTA application-managed entity manager is used, an application-managed persistence context
may be specified to be of type SynchronizationType.UNSYNCHRONIZED. A persistence context of type SynchronizationType.UNSYNCHRONIZED is not enlisted in any JTA transaction
unless explicitly joined to that transaction by the application. A persistence context of type SynchronizationType.UNSYNCHRONIZED is enlisted in a JTA transaction and registered for subsequent
transaction notifications against that transaction by the invocation of the EntityManager joinTransaction method. The persistence context remains joined to the transaction until the transaction
commits or rolls back. After the transaction commits or rolls back, the persistence context will not be
joined to any subsequent transaction unless the joinTransaction method is invoked in the scope
of that subsequent transaction.
When a JTA application-managed entity manager is used, if the entity manager is created outside the
scope of the current JTA transaction, it is the responsibility of the application to join the entity manager
to the transaction (if desired) by calling EntityManager.joinTransaction. If the entity manager is created outside the scope of a JTA transaction, it is not joined to the transaction unless EntityManager.joinTransaction is called.
The EntityManager.close method closes an entity manager to release its persistence context and
other resources. After calling close, the application must not invoke any further methods on the
EntityManager instance except for getTransaction and isOpen, or the IllegalStateException will be thrown. If the close method is invoked when a transaction is active, the persistence context remains managed until the transaction completes.
The EntityManager.isOpen method indicates whether the entity manager is open. The isOpen
method returns true until the entity manager has been closed.
JSR-338 Final Release
351
4/2/13
Oracle
Entity Managers and Persistence Contexts
Java Persistence 2.1, Final Release
Application-managed Persistence Contexts
7.7.1 Examples
7.7.1.1 Application-managed Persistence Context used in Stateless Session Bean
/*
* Container-managed transaction demarcation is used.
* The session bean creates and closes an entity manager
* in each business method.
*/
@Stateless
public class ShoppingCartImpl implements ShoppingCart {
@PersistenceUnit
private EntityManagerFactory emf;
public Order getOrder(Long id) {
EntityManager em = emf.createEntityManager();
Order order = em.find(Order.class, id);
order.getLineItems();
em.close();
return order;
}
public Product getProduct() {
EntityManager em = emf.createEntityManager();
Product product = (Product) em.createQuery("select p from
Product p where p.name = :name")
.setParameter("name", name)
.getSingleResult();
em.close();
return product;
}
public LineItem createLineItem(Order order, Product product, int
quantity) {
EntityManager em = emf.createEntityManager();
LineItem li = new LineItem(order, product, quantity);
order.getLineItems().add(li);
em.persist(li);
em.close();
return li; // remains managed until JTA transaction ends
}
}
4/2/13
352
JSR-338 Final Release
Oracle
Application-managed Persistence Contexts
Java Persistence 2.1, Final Release
Entity Managers and Persistence Contexts
7.7.1.2 Application-managed Persistence Context used in Stateless Session Bean
/*
* Container-managed transaction demarcation is used.
* The session bean creates entity manager in PostConstruct
* method and clears persistence context at the end of each
* business method.
*/
@Stateless
public class ShoppingCartImpl implements ShoppingCart {
@PersistenceUnit
private EntityManagerFactory emf;
private EntityManager em;
@PostConstruct
public void init()
em = emf.createEntityManager();
}
public Order getOrder(Long id) {
Order order = em.find(Order.class, id);
order.getLineItems();
em.clear(); // entities are detached
return order;
}
public Product getProduct() {
Product product = (Product) em.createQuery("select p from
Product p where p.name = :name")
.setParameter("name", name)
.getSingleResult();
em.clear();
return product;
}
public LineItem createLineItem(Order order, Product product, int
quantity) {
em.joinTransaction();
LineItem li = new LineItem(order, product, quantity);
order.getLineItems().add(li);
em.persist(li);
// persistence context is flushed to database;
// all updates will be committed to database on tx commit
em.flush();
}
// entities in persistence context are detached
em.clear();
return li;
@PreDestroy
public void destroy()
em.close();
}
}
JSR-338 Final Release
353
4/2/13
Oracle
Entity Managers and Persistence Contexts
Java Persistence 2.1, Final Release
Application-managed Persistence Contexts
7.7.1.3 Application-managed Persistence Context used in Stateful Session Bean
/*
* Container-managed transaction demarcation is used.
* Entities remain managed until the entity manager is closed.
*/
@Stateful
public class ShoppingCartImpl implements ShoppingCart {
@PersistenceUnit
private EntityManagerFactory emf;
private EntityManager em;
private Order order;
private Product product;
@PostConstruct
public void init() {
em = emf.createEntityManager();
}
public void initOrder(Long id) {
order = em.find(Order.class, id);
}
public void initProduct(String name) {
product = (Product) em.createQuery("select p from Product p
where p.name = :name")
.setParameter("name", name)
.getSingleResult();
}
public LineItem createLineItem(int quantity) {
em.joinTransaction();
LineItem li = new LineItem(order, product, quantity);
order.getLineItems().add(li);
em.persist(li);
return li;
}
@Remove
public void destroy() {
em.close();
}
}
4/2/13
354
JSR-338 Final Release
Oracle
Application-managed Persistence Contexts
Java Persistence 2.1, Final Release
Entity Managers and Persistence Contexts
7.7.1.4 Application-managed Persistence Context with Resource Transaction
// Usage in an ordinary Java class
public class ShoppingImpl {
private EntityManager em;
private EntityManagerFactory emf;
public ShoppingCart() {
emf = Persistence.createEntityManagerFactory("orderMgt");
em = emf.createEntityManager();
}
private Order order;
private Product product;
public void initOrder(Long id) {
order = em.find(Order.class, id);
}
public void initProduct(String name) {
product = (Product) em.createQuery("select p from Product p
where p.name = :name")
.setParameter("name", name)
.getSingleResult();
}
public LineItem createLineItem(int quantity) {
em.getTransaction().begin();
LineItem li = new LineItem(order, product, quantity);
order.getLineItems().add(li);
em.persist(li);
em.getTransaction().commit();
}
return li;
public void destroy() {
em.close();
emf.close();
}
}
JSR-338 Final Release
355
4/2/13
Oracle
Entity Managers and Persistence Contexts
Java Persistence 2.1, Final Release
Requirements on the Container
7.8 Requirements on the Container
7.8.1 Application-managed Persistence Contexts
When application-managed persistence contexts are used, the container must instantiate the entity manager factory and expose it to the application via JNDI. The container might use internal APIs to create
the entity manager factory, or it might use the PersistenceProvider.createContainerEntityManagerFactory method. However, the container is required to support third-party persistence
providers,
and
in
this
case
the
container
must
use
the
PersistenceProvider.createContainerEntityManagerFactory method to create the
entity manager factory and the EntityManagerFactory.close method to destroy the entity
manager factory prior to shutdown (if it has not been previously closed by the application).
7.8.2 Container Managed Persistence Contexts
The container is responsible for managing the lifecycle of container-managed persistence contexts, for
injecting EntityManager references into web components and session bean and message-driven
bean components, and for making EntityManager references available to direct lookups in JNDI.
When operating with a third-party persistence provider, the container uses the contracts defined in section 7.9 to create and destroy container-managed persistence contexts. It is undefined whether a new
entity manager instance is created for every persistence context, or whether entity manager instances are
sometimes reused. Exactly how the container maintains the association between persistence context and
JTA transaction is not defined.
If a persistence context is already associated with a JTA transaction, the container uses that persistence
context for subsequent invocations within the scope of that transaction, according to the semantics for
persistence context propagation defined in section 7.6.4.
7.9 Runtime Contracts between the Container and Persistence
Provider
This section describes contracts between the container and the persistence provider for the pluggability
of third-party persistence providers. Containers are required to support these pluggability contracts.[85]
7.9.1 Container Responsibilities
For the management of a transaction-scoped persistence context, if there is no EntityManager already
associated with the JTA transaction:
[85] It is not required that these contracts be used when a third-party persistence provider is not used: the container might use these
same APIs or its might use its own internal APIs.
4/2/13
356
JSR-338 Final Release
Oracle
Runtime Contracts between the Container and Persistence ProviderJava Persistence 2.1, Final Release
Entity Managers and Persis-
• The container creates a new entity manager by calling EntityManagerFactory.crea-
teEntityManager when the first invocation of an entity manager with PersistenceContextType.TRANSACTION occurs within the scope of a business method executing in
the JTA transaction.
• After the JTA transaction has completed (either by transaction commit or rollback), the container closes the entity manager by calling EntityManager.close. [86] Note that the JTA
transaction may rollback in a background thread (e.g., as a result of transaction timeout), in
which case the container should arrange for the entity manager to be closed but the EntityManager.close method should not be concurrently invoked while the application is in an
EntityManager invocation.
The container must throw the TransactionRequiredException if a transaction-scoped persistence context is used and the EntityManager persist, remove, merge, or refresh method is
invoked when no transaction is active.
For stateful session beans with extended persistence contexts:
• The container creates an entity manager by calling EntityManagerFactory.crea-
teEntityManager when a stateful session bean is created that declares a dependency on an
entity manager with PersistenceContextType.EXTENDED. (See section 7.6.3).
• The container closes the entity manager by calling EntityManager.close after the state-
ful session bean and all other stateful session beans that have inherited the same persistence
context as the entity manager have been removed.
• When a business method of the stateful session bean is invoked, if the stateful session bean
uses container managed transaction demarcation, and the entity manager is not already associated with the current JTA transaction, the container associates the entity manager with the current
JTA
transaction
and,
if
the
persistence
context
is
of
type
SynchronizationType.SYNCHRONIZED, the container calls EntityManager.joinTransaction. If there is a different persistence context already associated
with the JTA transaction, the container throws the EJBException.
• When a business method of the stateful session bean is invoked, if the stateful session bean
uses bean managed transaction demarcation and a UserTransaction is begun within the
method, the container associates the persistence context with the JTA transaction and, if the
persistence context is of type SynchronizationType.SYNCHRONIZED, the container
calls EntityManager.joinTransaction.
The container must throw the IllegalStateException if the application calls EntityManager.close on a container-managed entity manager.
[86] The container may choose to pool EntityManagers: it instead of creating and closing in each case, it may acquire one from its pool
and call clear() on it.
JSR-338 Final Release
357
4/2/13
Oracle
Entity Managers and Persistence Contexts
Java Persistence 2.1, Final Release
Runtime Contracts between the Container and
When the container creates an entity manager, it may pass a map of properties to the persistence provider by using the EntityManagerFactory.createEntityManager(Map map) method. If
properties have been specified in the PersistenceContext annotation or the persistence-context-ref deployment descriptor element, this method must be used and the map must
include the specified properties.
If the application invokes EntityManager.unwrap(Class<T> cls), and the container cannot
satisfy the request, the container must delegate the unwrap invocation to the provider’s entity manager
instance.
7.9.2 Provider Responsibilities
The Provider has no knowledge of the distinction between transaction-scoped and extended persistence
contexts. It provides entity managers to the container when requested and registers for transaction synchronization notifications.
• When EntityManagerFactory.createEntityManager is invoked, the provider
must create and return a new entity manager. If a JTA transaction is active and the persistence
context is of type SynchronizationType.SYNCHRONIZED, the provider must register
for synchronization notifications against the JTA transaction.
• When EntityManager.joinTransaction is invoked, the provider must register for
synchronization notifications against the current JTA transaction if a previous joinTransaction invocation for the transaction has not already been processed.
• When the JTA transaction commits, if the persistence context is of type Synchroniza-
tionType.SYNCHRONIZED or has otherwise been joined to the transaction, the provider
must flush all modified entity state to the database.
• When the JTA transaction rolls back, the provider must detach all managed entities if the persistence context is of type SynchronizationType.SYNCHRONIZED or has otherwise
been joined to the transaction. Note that the JTA transaction may rollback in a background
thread (e.g., as a result of transaction timeout), in which case the provider should arrange for
the managed entities to be detached from the persistence context but not concurrently while the
application is in an EntityManager invocation.
• When the provider throws an exception defined to cause transaction rollback, the provider
must mark the transaction for rollback if the persistence context is of type SynchronizationType.SYNCHRONIZED or has otherwise been joined to the transaction.
• When EntityManager.close is invoked, the provider should release all resources that it
may have allocated after any outstanding transactions involving the entity manager have completed. If the entity manager was already in a closed state, the provider must throw the IllegalStateException.
• When EntityManager.clear is invoked, the provider must detach all managed entities.
4/2/13
358
JSR-338 Final Release
Oracle
Cache Interface
Java Persistence 2.1, Final Release
Entity Managers and Persistence Contexts
7.10 Cache Interface
The Cache interface provides basic functionality over the persistence provider’s second level cache, if
used.
package javax.persistence;
/**
* Interface used to interact with the second-level cache.
* If a cache is not in use, the methods of this interface have
* no effect, except for contains, which returns false.
*/
public interface Cache {
/**
* Whether the cache contains
* @param cls entity class
* @param primaryKey primary
* @return boolean indicating
*/
public boolean contains(Class
data for the given entity.
key
whether the entity is in the cache
cls, Object primaryKey);
/**
* Remove the data for the given entity from the cache.
* @param cls entity class
* @param primaryKey primary key
*/
public void evict(Class cls, Object primaryKey);
/**
* Remove the data for entities of the specified class (and its
* subclasses) from the cache.
* @param cls entity class
*/
public void evict(Class cls);
/**
* Clear the cache.
*/
public void evictAll();
/**
* Return an object of the specified type to allow access to the
* provider-specific API.
If the provider's Cache
* implementation does not support the specified class, the
* PersistenceException is thrown.
* @param cls the class of the object to be returned. This is
* normally either the underlying Cache implementation
* class or an interface that it implements.
* @return an instance of the specified class
* @throws PersistenceException if the provider does not
*
support the call
*/
public <T> T unwrap(Class<T> cls);
}
JSR-338 Final Release
359
4/2/13
Oracle
Entity Managers and Persistence Contexts
Java Persistence 2.1, Final Release
PersistenceUnitUtil Interface
7.11 PersistenceUnitUtil Interface
The PersistenceUnitUtil interface provides access to utility methods that can be invoked on
entities associated with the persistence unit. The behavior is undefined if these methods are invoked on
an entity instance that is not associated with the persistence unit from whose entity manager factory this
interface has been obtained.
package javax.persistence;
/**
* Utility interface between the application and the persistence
* provider managing the persistence unit.
*
* The methods of this interface should only be invoked on entity
* instances obtained from or managed by entity managers for this
* persistence unit or on new entity instances.
*/
public interface PersistenceUnitUtil extends PersistenceUtil {
/**
* Determine the load state of a given persistent attribute
* of an entity belonging to the persistence unit.
* @param entity entity instance containing the attribute
* @param attributeName name of attribute whose load state is
*
to be determined
* @return false if entity's state has not been loaded or if
*
the attribute state has not been loaded, else true
*/
public boolean isLoaded(Object entity, String attributeName);
/**
* Determine the load state of an entity belonging to the
* persistence unit.
* This method can be used to determine the load state
* of an entity passed as a reference. An entity is
* considered loaded if all attributes for which FetchType
* EAGER has been specified have been loaded.
* The isLoaded(Object, String) method should be used to
* determine the load state of an attribute.
* Not doing so might lead to unintended loading of state.
* @param entity entity whose load state is to be determined
* @return false if the entity has not been loaded, else true
*/
public boolean isLoaded(Object entity);
}
4/2/13
/**
* Return the id of the entity.
* A generated id is not guaranteed to be available until after
* the database insert has occurred.
* Returns null if the entity does not yet have an id.
* @param entity entity instance
* @return id of the entity
* @throws IllegalArgumentException if the object is found not
*
to be an entity
*/
public Object getIdentifier(Object entity);
360
JSR-338 Final Release
Oracle
Persistence Unit
Ch apt er 8
Java Persistence 2.1, Final Release
Entity Packaging
Entity Packaging
This chapter describes the packaging of persistence units.
8.1 Persistence Unit
A persistence unit is a logical grouping that includes:
• An entity manager factory and its entity managers, together with their configuration information.
• The set of managed classes included in the persistence unit and managed by the entity managers of the entity manager factory.
• Mapping metadata (in the form of metadata annotations and/or XML metadata) that specifies
the mapping of the classes to the database.
JSR-338 Final Release
361
4/2/13
Oracle
Entity Packaging
Java Persistence 2.1, Final Release
Persistence Unit Packaging
8.2 Persistence Unit Packaging
Within Java EE environments, an EJB-JAR, WAR, EAR, or application client JAR can define a persistence unit. Any number of persistence units may be defined within these scopes.
A persistence unit may be packaged within one or more jar files contained within a WAR or EAR, as a
set of classes within an EJB-JAR file or in the WAR classes directory, or as a combination of these
as defined below.
A persistence unit is defined by a persistence.xml file. The jar file or directory whose
META-INF directory contains the persistence.xml file is termed the root of the persistence unit.
In Java EE environments, the root of a persistence unit must be one of the following:
• an EJB-JAR file
• the WEB-INF/classes directory of a WAR file[87]
• a jar file in the WEB-INF/lib directory of a WAR file
• a jar file in the EAR library directory
• an application client jar file
It is not required that an EJB-JAR or WAR file containing a persistence unit be packaged in an EAR
unless the persistence unit contains persistence classes in addition to those contained within the
EJB-JAR or WAR. See Section 8.2.1.6.
NOTE: Java Persistence 1.0 supported use of a jar file in the root of the EAR as the root of a
persistence unit. This use is no longer supported. Portable applications should use the EAR
library directory for this case instead. See [9].
A persistence unit must have a name. Only one persistence unit of any given name must be defined
within a single EJB-JAR file, within a single WAR file, within a single application client jar, or within
an EAR. See Section 8.2.2, “Persistence Unit Scope”.
The persistence.xml file may be used to designate more than one persistence unit within the same
scope.
All persistence classes defined at the level of the Java EE EAR must be accessible to other Java EE
components in the application—i.e. loaded by the application classloader—such that if the same entity
class is referenced by two different Java EE components (which may be using different persistence
units), the referenced class is the same identical class.
[87] The root of the persistence unit is the WEB-INF/classes directory; the persistence.xml file is therefore contained in the
WEB-INF/classes/META-INF directory.
4/2/13
362
JSR-338 Final Release
Oracle
Persistence Unit Packaging
Java Persistence 2.1, Final Release
Entity Packaging
In Java SE environments, the metadata mapping files, jar files, and classes described in the following
sections can be used. To insure the portability of a Java SE application, it is necessary to explicitly list
the managed persistence classes that are included in the persistence unit using the class element of
the persistence.xml file. See Section 8.2.1.6.
8.2.1 persistence.xml file
A persistence.xml file defines a persistence unit. The persistence.xml file is located in the
META-INF directory of the root of the persistence unit. It may be used to specify managed persistence
classes included in the persistence unit, object/relational mapping information for those classes, scripts
for use in schema generation and the bulk loading of data, and other configuration information for the
persistence unit and for the entity manager(s) and entity manager factory for the persistence unit. This
information may be defined by containment or by reference, as described below.
The object/relational mapping information can take the form of annotations on the managed persistence
classes included in the persistence unit, an orm.xml file contained in the META-INF directory of the
root of the persistence unit, one or more XML files on the classpath and referenced from the persistence.xml file, or a combination of these.
The managed persistence classes may either be contained within the root of the persistence unit; or they
may be specified by reference—i.e., by naming the classes, class archives, or XML mapping files
(which in turn reference classes) that are accessible on the application classpath; or they may be specified by some combination of these means. See Section 8.2.1.6.
The root element of the persistence.xml file is the persistence element. The persistence element consists of one or more persistence-unit elements.
The persistence-unit element consists of the name and transaction-type attributes and
the
following
sub-elements:
description,
provider,
jta-data-source,
non-jta-data-source,
mapping-file,
jar-file,
class,
exclude-unlisted-classes, shared-cache-mode, validation-mode, and properties.
The name attribute is required; the other attributes and elements are optional. Their semantics are
described in the following subsections.
JSR-338 Final Release
363
4/2/13
Oracle
Entity Packaging
Java Persistence 2.1, Final Release
Persistence Unit Packaging
Examples:
<persistence>
<persistence-unit name="OrderManagement">
<description>
This unit manages orders and customers.
It does not rely on any vendor-specific features and can
therefore be deployed to any persistence provider.
</description>
<jta-data-source>jdbc/MyOrderDB</jta-data-source>
<mapping-file>ormap.xml</mapping-file>
<jar-file>MyOrderApp.jar</jar-file>
<class>com.widgets.Order</class>
<class>com.widgets.Customer</class>
</persistence-unit>
</persistence>
<persistence>
<persistence-unit name="OrderManagement2">
<description>
This unit manages inventory for auto parts.
It depends on features provided by the
com.acme.persistence implementation.
</description>
<provider>com.acme.AcmePersistence</provider>
<jta-data-source>jdbc/MyPartDB</jta-data-source>
<mapping-file>ormap2.xml</mapping-file>
<jar-file>MyPartsApp.jar</jar-file>
<properties>
<property
name="com.acme.persistence.sql-logging"
value="on"/>
</properties>
</persistence-unit>
</persistence>
8.2.1.1 name
The name attribute defines the name for the persistence unit. This name may be used to identify a persistence unit referred to by the PersistenceContext and PersistenceUnit annotations and
in the programmatic API for creating an entity manager factory.
8.2.1.2 transaction-type
The transaction-type attribute is used to specify whether the entity managers provided by the
entity manager factory for the persistence unit must be JTA entity managers or resource-local entity
managers. The value of this element is JTA or RESOURCE_LOCAL. A transaction-type of JTA
assumes that a JTA data source will be provided—either as specified by the jta-data-source element or provided by the container. In general, in Java EE environments, a transaction-type of
RESOURCE_LOCAL assumes that a non-JTA datasource will be provided. In a Java EE environment, if
this element is not specified, the default is JTA. In a Java SE environment, if this element is not specified, the default is RESOURCE_LOCAL.
4/2/13
364
JSR-338 Final Release
Oracle
Persistence Unit Packaging
Java Persistence 2.1, Final Release
Entity Packaging
8.2.1.3 description
The description element provides optional descriptive information about the persistence unit.
8.2.1.4 provider
The provider element specifies the name of the persistence provider's javax.persistence.spi.PersistenceProvider class. The provider element is optional, but should be
specified if the application is dependent upon a particular persistence provider being used.
8.2.1.5 jta-data-source, non-jta-data-source
In Java EE environments, the jta-data-source and non-jta-data-source elements are
used to specify the JNDI name of the JTA and/or non-JTA data source to be used by the persistence provider. If neither is specified, the deployer must specify a JTA data source at deployment or the default
JTA data source must be provided by the container, and a JTA EntityManagerFactory will be created to
correspond to it.
In Java SE environments, these elements may be used or the data source information may be specified
by other means—depending upon the requirements of the provider.
8.2.1.6 mapping-file, jar-file, class, exclude-unlisted-classes
The following classes must be implicitly or explicitly denoted as managed persistence classes to be
included within a persistence unit: entity classes; embeddable classes; mapped superclasses; converter
classes.
The set of managed persistence classes that are managed by a persistence unit is defined by using one or
more of the following:[88]
• Annotated managed persistence classes contained in the root of the persistence unit (unless the
exclude-unlisted-classes element is specified)
• One or more object/relational mapping XML files
• One or more jar files that will be searched for classes
• An explicit list of classes
The set of entities managed by the persistence unit is the union of these sources, with the mapping metadata annotations (or annotation defaults) for any given class being overridden by the XML mapping
information file if there are both annotations as well as XML mappings for that class. The minimum
portable level of overriding is at the level of the persistent field or property.
The classes and/or jars that are named as part of a persistence unit must be on the classpath; referencing
them from the persistence.xml file does not cause them to be placed on the classpath.
All classes must be on the classpath to ensure that entity managers from different persistence units that
map the same class will be accessing the same identical class.
[88] Note that an individual class may be used in more than one persistence unit.
JSR-338 Final Release
365
4/2/13
Oracle
Entity Packaging
Java Persistence 2.1, Final Release
Persistence Unit Packaging
8.2.1.6.1 Annotated Classes in the Root of the Persistence Unit
All classes contained in the root of the persistence unit are searched for annotated managed persistence
classes—classes with the Entity, Embeddable, MappedSuperclass, or Converter annotation—and any mapping metadata annotations found on these classes will be processed, or they will be
mapped using the mapping annotation defaults. If it is not intended that the annotated persistence
classes contained in the root of the persistence unit be included in the persistence unit, the
exclude-unlisted-classes
element
must
be
specified
as
true.
The
exclude-unlisted-classes element is not intended for use in Java SE environments.
8.2.1.6.2 Object/relational Mapping Files
An object/relational mapping XML file contains mapping information for the classes listed in it.
An object/relational mapping XML file named orm.xml may be specified in the META-INF directory
in the root of the persistence unit or in the META-INF directory of any jar file referenced by the persistence.xml. Alternatively, or in addition, one or more mapping files may be referenced by the
mapping-file elements of the persistence-unit element. These mapping files may be
present anywhere on the class path.
An orm.xml mapping file or other mapping file is loaded as a resource by the persistence provider. If
a mapping file is specified, the classes and mapping information specified in the mapping file will be
used as described in Chapter 12. If multiple mapping files are specified (possibly including one or more
orm.xml files), the resulting mappings are obtained by combining the mappings from all of the files.
The result is undefined if multiple mapping files (including any orm.xml file) referenced within a single persistence unit contain overlapping mapping information for any given class. The object/relational
mapping information contained in any mapping file referenced within the persistence unit must be disjoint at the class-level from object/relational mapping information contained in any other such mapping
file.
8.2.1.6.3 Jar Files
One or more JAR files may be specified using the jar-file elements instead of, or in addition to the
mapping files specified in the mapping-file elements. If specified, these JAR files will be searched
for managed persistence classes, and any mapping metadata annotations found on them will be processed, or they will be mapped using the mapping annotation defaults defined by this specification.
Such JAR files are specified relative to the directory or jar file that contains[89] the root of the persistence unit.[90]
The following examples illustrate the use of the jar-file element to reference additional persistence
classes. These examples use the convention that a jar file with a name terminating in “PUnit” contains
the persistence.xml file and that a jar file with a name terminating in “Entities” contains
additional persistence classes.
[89] This semantics applies to persistence.xml files written to the persistence_2_0.xsd or later schema. Due to ambiguity in the Java
Persistence 1.0 specification, provider-specific interpretation of the relative references used by this element may apply to earlier
versions.
[90] Persistence providers are encouraged to support this syntax for use in Java SE environments.
4/2/13
366
JSR-338 Final Release
Oracle
Persistence Unit Packaging
Java Persistence 2.1, Final Release
Entity Packaging
Example 1:
app.ear
lib/earEntities.jar
earRootPUnit.jar (with META-INF/persistence.xml )
persistence.xml contains:
<jar-file>lib/earEntities.jar</jar-file>
Example 2:
app.ear
lib/earEntities.jar
lib/earLibPUnit.jar
(with META-INF/persistence.xml )
persistence.xml contains:
<jar-file>earEntities.jar</jar-file>
Example 3:
app.ear
lib/earEntities.jar
ejbjar.jar (with META-INF/persistence.xml )
persistence.xml contains:
<jar-file>lib/earEntities.jar</jar-file>
Example 4:
app.ear
war1.war
WEB-INF/lib/warEntities.jar
WEB-INF/lib/warPUnit.jar (with
META-INF/persistence.xml )
persistence.xml contains:
<jar-file>warEntities.jar</jar-file>
Example 5:
app.ear
war2.war
WEB-INF/lib/warEntities.jar
WEB-INF/classes/META-INF/persistence.xml
JSR-338 Final Release
367
4/2/13
Oracle
Entity Packaging
Java Persistence 2.1, Final Release
Persistence Unit Packaging
persistence.xml contains:
<jar-file>lib/warEntities.jar</jar-file>
Example 6:
app.ear
lib/earEntities.jar
war2.war
WEB-INF/classes/META-INF/persistence.xml
persistence.xml contains:
<jar-file>../../lib/earEntities.jar</jar-file>
Example 7:
app.ear
lib/earEntities.jar
war1.war
WEB-INF/lib/warPUnit.jar
(with
META-INF/persistence.xml )
persistence.xml contains:
<jar-file>../../../lib/earEntities.jar</jar-file>
8.2.1.6.4 List of Managed Classes
A list of named managed persistence classes—entity classes, embeddable classes, mapped superclasses,
and converter classes—may be specified instead of, or in addition to, the JAR files and mapping files.
Any mapping metadata annotations found on these classes will be processed, or they will be mapped
using the mapping annotation defaults. The class element is used to list a managed persistence class.
A list of all named managed persistence classes must be specified in Java SE environments to insure
portability. Portable Java SE applications should not rely on the other mechanisms described here to
specify the managed persistence classes of a persistence unit. Persistence providers may require that the
set of entity classes and classes that are to be managed must be fully enumerated in each of the persistence.xml files in Java SE environments.
8.2.1.7 shared-cache-mode
The shared-cache-mode element determines whether second-level caching is in effect for the persistence unit. See section 3.9.1.
8.2.1.8 validation-mode
The validation-mode element determines whether automatic lifecycle event time validation is in
effect. See section 3.6.1.1.
4/2/13
368
JSR-338 Final Release
Oracle
Persistence Unit Packaging
Java Persistence 2.1, Final Release
Entity Packaging
8.2.1.9 properties
The properties element is used to specify both standard and vendor-specific properties and hints
that apply to the persistence unit and its entity manager factory configuration.
The following properties and hints defined by this specification are intended for use in both Java EE and
Java SE environments:
• javax.persistence.lock.timeout — value in milliseconds for pessimistic lock
timeout. This is a hint only.
• javax.persistence.query.timeout — value in milliseconds for query timeout.
This is a hint only.
• javax.persistence.validation.group.pre-persist— groups that are targeted for validation upon the pre-persist event (overrides the default behavior).
• javax.persistence.validation.group.pre-update— groups that are targeted
for validation upon the pre-update event (overrides the default behavior).
• javax.persistence.validation.group.pre-remove— groups that are targeted
for validation upon the pre-remove event (overrides the default behavior).
The following properties defined by this specification are intended for use in Java SE environments.
• javax.persistence.jdbc.driver — fully qualified name of the driver class
• javax.persistence.jdbc.url — driver-specific URL
• javax.persistence.jdbc.user — username used by database connection
• javax.persistence.jdbc.password — password for database connection validation
Scripts for use in schema generation may be specified using the javax.persistence.schema-generation.create-script-source
and
javax.persistence.schema-generation.drop-script-source properties. A script to specify SQL for
the
bulk
loading
of
data
may
be
specified
by
the
javax.persistence.sql-load-script-source property. These properties are intended for use in both Java
EE and Java SE environments:
• javax.persistence.schema-generation.create-script-source — name
of a script packaged as part of the persistence application or a string corresponding to a file
URL string that designates a script.
• javax.persistence.schema-generation.drop-script-source — name of
a script packaged as part of the persistence application or a string corresponding to a file URL
string that designates a script.
JSR-338 Final Release
369
4/2/13
Oracle
Entity Packaging
Java Persistence 2.1, Final Release
Persistence Unit Packaging
• javax.persistence.sql-load-script-source — name of a script packaged as
part of the persistence unit or a string corresponding to a file URL string that designates a
script.
When scripts are packaged as part of the persistence application, these properties must specify locations
relative to the root of the persistence unit. When scripts are provided externally (or when schema generation is to occur into script files, as described below), strings corresponding to file URLs must be specified. In Java EE environments, such file URL specifications must be absolute paths (not relative). In
Java EE environments, all source and target file locations must be accessible to the application server
deploying the persistence unit.
In general, it is expected that schema generation will be initiated by means of the APIs described in Section 9.4. However, schema generation actions may also be specified by means of the following properties used in the persistence.xml file.
• javax.persistence.schema-generation.database.action
The javax.persistence.schema-generation.database.action property
specifies the action to be taken by the persistence provider with regard to the database artifacts.
The values for this property are none, create, drop-and-create, drop. If this property is not specified, it is assumed that schema generation is not needed or will be initiated by
other means, and, by default, no schema generation actions will be taken on the database. (See
Section 9.4.)
• javax.persistence.schema-generation.scripts.action
The javax.persistence.schema-generation.scripts.action property specifies which scripts are to be generated by the persistence provider. The values for this property
are none, create, drop-and-create, drop. A script will only be generated if the script
target is specified. If this property is not specified, it is assumed that script generation is not
needed or will be initiated by other means, and, by default, no scripts will be generated. (See
Section 9.4.)
• javax.persistence.schema-generation.create-source
The javax.persistence.schema-generation.create-source property specifies whether the creation of database artifacts is to occur on the basis of the object/relational
mapping metadata, DDL script, or a combination of the two. The values for this property are
metadata, script, metadata-then-script, script-then-metadata. If this
property is not specified, and a script is specified by the javax.persistence.schema-generation.create-script-source property, the script (only)
will be used for schema generation; otherwise if this property is not specified, schema generation will occur on the basis of the object/relational mapping metadata (only). The metadata-then-script and script-then-metadata values specify that a combination
of metadata and script is to be used and the order in which this use is to occur. If either of these
values is specified and the resulting database actions are not disjoint, the results are undefined
and schema generation may fail.
• javax.persistence.schema-generation.drop-source
The javax.persistence.schema-generation.drop-source property specifies
whether the dropping of database artifacts is to occur on the basis of the object/relational mapping metadata, DDL script, or a combination of the two. The values for this property are
4/2/13
370
JSR-338 Final Release
Oracle
Persistence Unit Packaging
Java Persistence 2.1, Final Release
Entity Packaging
metadata, script, metadata-then-script, script-then-metadata. If this
property is not specified, and a script is specified by the javax.persistence.schema-generation.drop-script-source property, the script (only) will
be used for the dropping of database artifacts; otherwise if this property is not specified, the
dropping of database artifacts will occur on the basis of the object/relational mapping metadata
(only). The metadata-then-script and script-then-metadata values specify
that a combination of metadata and script is to be used and the order in which this use is to
occur. If either of these values is specified and the resulting database actions are not disjoint,
the results are undefined and the dropping of database artifacts may fail.
• javax.persistence.schema-generation.scripts.create-target,
javax.persistence.schema-generation.scripts.drop-target
If scripts are to be generated, the target locations for the writing of these scripts must be specified. These targets are specified as strings corresponding to file URLs.
If a persistence provider does not recognize a property (other than a property defined by this specification), the provider must ignore it.
Vendors should use vendor namespaces for properties (e.g., com.acme.persistence.logging).
Entries that make use of the namespace javax.persistence and its subnamespaces must not be
used for vendor-specific information. The namespace javax.persistence is reserved for use by
this specification.
8.2.1.10 Examples
The following are sample contents of a persistence.xml file.
Example 1:
<persistence-unit name="OrderManagement"/>
A persistence unit named OrderManagement is created.
Any annotated managed persistence classes found in the root of the persistence unit are added to the list
of managed persistence classes. If a META-INF/orm.xml file exists, any classes referenced by it and
mapping information contained in it are used as specified above. Because no provider is specified, the
persistence unit is assumed to be portable across providers. Because the transaction type is not specified, JTA is assumed for Java EE environments. The container must provide the data source (it may be
specified at application deployment, for example). In Java SE environments, the data source may be
specified by other means and a transaction type of RESOURCE_LOCAL is assumed.
Example 2:
<persistence-unit name="OrderManagement2">
<mapping-file>mappings.xml</mapping-file>
</persistence-unit>
JSR-338 Final Release
371
4/2/13
Oracle
Entity Packaging
Java Persistence 2.1, Final Release
Persistence Unit Packaging
A persistence unit named OrderManagement2 is created. Any annotated managed persistence
classes found in the root of the persistence unit are added to the list of managed persistence classes. The
mappings.xml resource exists on the classpath and any classes and mapping information contained
in it are used as specified above. If a META-INF/orm.xml file exists, any classes and mapping information contained in it are used as well. The transaction type, data source, and provider are as described
above.
Example 3:
<persistence-unit name="OrderManagement3">
<jar-file>order.jar</jar-file>
<jar-file>order-supplemental.jar</jar-file>
</persistence-unit>
A persistence unit named OrderManagement3 is created. Any annotated managed persistence
classes found in the root of the persistence unit are added to the list of managed persistence classes. If a
META-INF/orm.xml file exists, any classes and mapping information contained in it are used as
specified above. The order.jar and order-supplemental.jar files are searched for managed
persistence classes and any annotated managed persistence classes found in them and/or any classes
specified in the orm.xml files of these jar files are added. The transaction-type, data source and provider are as described above.
Example 4:
<persistence-unit
name="OrderManagement4"
transaction-type=RESOURCE_LOCAL>
<non-jta-data-source>java:app/jdbc/MyDB</non-jta-data-source>
<mapping-file>order-mappings.xml</mapping-file>
<class>com.acme.Order</class>
<class>com.acme.Customer</class>
<class>com.acme.Item</class>
<exclude-unlisted-classes/>
</persistence-unit>
A persistence unit named OrderManagement4 is created. The file order-mappings.xml is read
as a resource and any classes referenced by it and mapping information contained in it are used[91]. The
annotated Order, Customer and Item classes are loaded and are added. No (other) classes contained in the root of the persistence unit are added to the list of managed persistence classes. The persistence unit assumed to be portable across providers. A entity manager factory supplying resource-local
entity managers will be created. The data source java:app/jdbc/MyDB must be used.
[91] Note that in this example a META-INF/orm.xml file is assumed not to exist.
4/2/13
372
JSR-338 Final Release
Oracle
Persistence Unit Packaging
Java Persistence 2.1, Final Release
Entity Packaging
Example 5:
<persistence-unit name="OrderManagement5">
<provider>com.acme.AcmePersistence</provider>
<mapping-file>order1.xml</mapping-file>
<mapping-file>order2.xml</mapping-file>
<jar-file>order.jar</jar-file>
<jar-file>order-supplemental.jar</jar-file>
</persistence-unit>
A persistence unit named OrderManagement5 is created. Any annotated managed persistence
classes found in the root of the persistence unit are added to the list of managed classes. The
order1.xml and order2.xml files are read as resources and any classes referenced by them and
mapping information contained in them are also used as specified above. The order.jar is a jar file
on the classpath containing another persistence unit, while order-supplemental.jar is just a
library of classes. Both of these jar files are searched for annotated managed persistence classes and
any annotated managed persistence classes found in them and any classes specified in the orm.xml
files (if any) of these jar files are added. The provider com.acme.AcmePersistence must be
used.
Note that the persistence.xml file contained in order.jar is not used to augment the
persistence unit OrderManagement5 with the classes of the persistence unit whose root is
order.jar.
8.2.2 Persistence Unit Scope
An EJB-JAR, WAR, application client jar, or EAR can define a persistence unit.
When referencing a persistence unit using the unitName annotation element or persistence-unit-name deployment descriptor element, the visibility scope of the persistence unit is
determined by its point of definition:
• A persistence unit that is defined at the level of an EJB-JAR, WAR, or application client jar is
scoped to that EJB-JAR, WAR, or application jar respectively and is visible to the components
defined in that jar or war.
• A persistence unit that is defined at the level of the EAR is generally visible to all components
in the application. However, if a persistence unit of the same name is defined by an EJB-JAR,
WAR, or application jar file within the EAR, the persistence unit of that name defined at EAR
level will not be visible to the components defined by that EJB-JAR, WAR, or application jar
file unless the persistence unit reference uses the persistence unit name # syntax to specify a
path name to disambiguate the reference. When the # syntax is used, the path name is relative
to the referencing application component jar file. For example, the syntax ../lib/persistenceUnitRoot.jar#myPersistenceUnit refers to a persistence unit whose name,
as specified in the name element of the persistence.xml file, is myPersistenceUnit
and for which the relative path name of the root of the persistence unit is ../lib/persistenceUnitRoot.jar. The # syntax may be used with both the unitName annotation element or persistence-unit-name deployment descriptor element to reference a
persistence unit defined at EAR level.
JSR-338 Final Release
373
4/2/13
Oracle
Entity Packaging
Java Persistence 2.1, Final Release
persistence.xml Schema
8.3 persistence.xml Schema
This section provides the XML schema for the persistence.xml file.
<?xml version="1.0" encoding="UTF-8"?>
<!-- persistence.xml schema -->
<xsd:schema targetNamespace="http://xmlns.jcp.org/xml/ns/persistence"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:persistence="http://xmlns.jcp.org/xml/ns/persistence"
elementFormDefault="qualified"
attributeFormDefault="unqualified"
version="2.1">
<xsd:annotation>
<xsd:documentation>
@(#)persistence_2_1.xsd 2.1
</xsd:documentation>
</xsd:annotation>
<xsd:annotation>
<xsd:documentation><![CDATA[
February 4, 2013
This is the XML Schema for the persistence configuration file.
The file must be named "META-INF/persistence.xml" in the
persistence archive.
Persistence configuration files must indicate
the persistence schema by using the persistence namespace:
http://xmlns.jcp.org/xml/ns/persistence
and indicate the version of the schema by
using the version element as shown below:
<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"
version="2.1">
...
</persistence>
]]></xsd:documentation>
</xsd:annotation>
<xsd:simpleType name="versionType">
<xsd:restriction base="xsd:token">
<xsd:pattern value="[0-9]+(\.[0-9]+)*"/>
</xsd:restriction>
</xsd:simpleType>
<!-- **************************************************** -->
<xsd:element name="persistence">
<xsd:complexType>
<xsd:sequence>
<!-- **************************************************** -->
<xsd:element name="persistence-unit"
minOccurs="1" maxOccurs="unbounded">
<xsd:complexType>
<xsd:annotation>
<xsd:documentation>
4/2/13
374
JSR-338 Final Release
Oracle
persistence.xml Schema
Java Persistence 2.1, Final Release
Entity Packaging
Configuration of a persistence unit.
</xsd:documentation>
</xsd:annotation>
<xsd:sequence>
<!-- **************************************************** -->
<xsd:element name="description" type="xsd:string"
minOccurs="0">
<xsd:annotation>
<xsd:documentation>
Description of this persistence unit.
</xsd:documentation>
</xsd:annotation>
</xsd:element>
<!-- **************************************************** -->
<xsd:element name="provider" type="xsd:string"
minOccurs="0">
<xsd:annotation>
<xsd:documentation>
Provider class that supplies EntityManagers for this
persistence unit.
</xsd:documentation>
</xsd:annotation>
</xsd:element>
<!-- **************************************************** -->
<xsd:element name="jta-data-source" type="xsd:string"
minOccurs="0">
<xsd:annotation>
<xsd:documentation>
The container-specific name of the JTA datasource to use.
</xsd:documentation>
</xsd:annotation>
</xsd:element>
<!-- **************************************************** -->
<xsd:element name="non-jta-data-source" type="xsd:string"
minOccurs="0">
<xsd:annotation>
<xsd:documentation>
The container-specific name of a non-JTA datasource to use.
</xsd:documentation>
</xsd:annotation>
</xsd:element>
<!-- **************************************************** -->
<xsd:element name="mapping-file" type="xsd:string"
minOccurs="0" maxOccurs="unbounded">
<xsd:annotation>
<xsd:documentation>
JSR-338 Final Release
375
4/2/13
Oracle
Entity Packaging
Java Persistence 2.1, Final Release
persistence.xml Schema
File containing mapping information. Loaded as a resource
by the persistence provider.
</xsd:documentation>
</xsd:annotation>
</xsd:element>
<!-- **************************************************** -->
<xsd:element name="jar-file" type="xsd:string"
minOccurs="0" maxOccurs="unbounded">
<xsd:annotation>
<xsd:documentation>
Jar file that is to be scanned for managed classes.
</xsd:documentation>
</xsd:annotation>
</xsd:element>
<!-- **************************************************** -->
<xsd:element name="class" type="xsd:string"
minOccurs="0" maxOccurs="unbounded">
<xsd:annotation>
<xsd:documentation>
Managed class to be included in the persistence unit and
to scan for annotations. It should be annotated
with either @Entity, @Embeddable or @MappedSuperclass.
</xsd:documentation>
</xsd:annotation>
</xsd:element>
<!-- **************************************************** -->
<xsd:element name="exclude-unlisted-classes" type="xsd:boolean"
default="true" minOccurs="0">
<xsd:annotation>
<xsd:documentation>
When set to true then only listed classes and jars will
be scanned for persistent classes, otherwise the
enclosing jar or directory will also be scanned.
Not applicable to Java SE persistence units.
</xsd:documentation>
</xsd:annotation>
</xsd:element>
<!-- **************************************************** -->
<xsd:element name="shared-cache-mode"
type="persistence:persistence-unit-caching-type"
minOccurs="0">
<xsd:annotation>
<xsd:documentation>
Defines whether caching is enabled for the
persistence unit if caching is supported by the
persistence provider. When set to ALL, all entities
will be cached. When set to NONE, no entities will
be cached. When set to ENABLE_SELECTIVE, only entities
specified as cacheable will be cached. When set to
4/2/13
376
JSR-338 Final Release
Oracle
persistence.xml Schema
Java Persistence 2.1, Final Release
Entity Packaging
DISABLE_SELECTIVE, entities specified as not cacheable
will not be cached. When not specified or when set to
UNSPECIFIED, provider defaults may apply.
</xsd:documentation>
</xsd:annotation>
</xsd:element>
<!-- **************************************************** -->
<xsd:element name="validation-mode"
type="persistence:persistence-unit-validation-mode-type"
minOccurs="0">
<xsd:annotation>
<xsd:documentation>
The validation mode to be used for the persistence unit.
</xsd:documentation>
</xsd:annotation>
</xsd:element>
<!-- **************************************************** -->
<xsd:element name="properties" minOccurs="0">
<xsd:annotation>
<xsd:documentation>
A list of standard and vendor-specific properties
and hints.
</xsd:documentation>
</xsd:annotation>
<xsd:complexType>
<xsd:sequence>
<xsd:element name="property"
minOccurs="0" maxOccurs="unbounded">
<xsd:annotation>
<xsd:documentation>
A name-value pair.
</xsd:documentation>
</xsd:annotation>
<xsd:complexType>
<xsd:attribute name="name" type="xsd:string"
use="required"/>
<xsd:attribute name="value" type="xsd:string"
use="required"/>
</xsd:complexType>
</xsd:element>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
</xsd:sequence>
<!-- **************************************************** -->
<xsd:attribute name="name" type="xsd:string" use="required">
<xsd:annotation>
<xsd:documentation>
Name used in code to reference this persistence unit.
</xsd:documentation>
JSR-338 Final Release
377
4/2/13
Oracle
Entity Packaging
Java Persistence 2.1, Final Release
persistence.xml Schema
</xsd:annotation>
</xsd:attribute>
<!-- **************************************************** -->
tion-type">
<xsd:attribute name="transaction-type"
type="persistence:persistence-unit-transac<xsd:annotation>
<xsd:documentation>
Type of transactions used by EntityManagers from this
persistence unit.
</xsd:documentation>
</xsd:annotation>
</xsd:attribute>
</xsd:complexType>
</xsd:element>
</xsd:sequence>
<xsd:attribute name="version" type="persistence:versionType"
fixed="2.1" use="required"/>
</xsd:complexType>
</xsd:element>
<!-- **************************************************** -->
<xsd:simpleType name="persistence-unit-transaction-type">
<xsd:annotation>
<xsd:documentation>
public enum PersistenceUnitTransactionType {JTA, RESOURCE_LOCAL};
</xsd:documentation>
</xsd:annotation>
<xsd:restriction base="xsd:token">
<xsd:enumeration value="JTA"/>
<xsd:enumeration value="RESOURCE_LOCAL"/>
</xsd:restriction>
</xsd:simpleType>
<!-- **************************************************** -->
<xsd:simpleType name="persistence-unit-caching-type">
<xsd:annotation>
<xsd:documentation>
public enum SharedCacheMode { ALL, NONE, ENABLE_SELECTIVE,
DISABLE_SELECTIVE, UNSPECIFIED};
</xsd:documentation>
</xsd:annotation>
<xsd:restriction base="xsd:token">
<xsd:enumeration value="ALL"/>
<xsd:enumeration value="NONE"/>
<xsd:enumeration value="ENABLE_SELECTIVE"/>
<xsd:enumeration value="DISABLE_SELECTIVE"/>
<xsd:enumeration value="UNSPECIFIED"/>
</xsd:restriction>
</xsd:simpleType>
<!-- **************************************************** -->
<xsd:simpleType name="persistence-unit-validation-mode-type">
<xsd:annotation>
4/2/13
378
JSR-338 Final Release
Oracle
persistence.xml Schema
Java Persistence 2.1, Final Release
Entity Packaging
<xsd:documentation>
public enum ValidationMode { AUTO, CALLBACK, NONE};
</xsd:documentation>
</xsd:annotation>
<xsd:restriction base="xsd:token">
<xsd:enumeration value="AUTO"/>
<xsd:enumeration value="CALLBACK"/>
<xsd:enumeration value="NONE"/>
</xsd:restriction>
</xsd:simpleType>
</xsd:schema>
JSR-338 Final Release
379
4/2/13
Oracle
Entity Packaging
4/2/13
Java Persistence 2.1, Final Release
persistence.xml Schema
380
JSR-338 Final Release
Oracle
Java EE Deployment
Ch apt er 9
Java Persistence 2.1, Final ReleaseContainer and Provider Contracts for Deployment
Container and Provider Contracts for
Deployment and Bootstrapping
This chapter defines requirements on the Java EE container and on the persistence provider for deployment and bootstrapping.
9.1 Java EE Deployment
Each persistence unit deployed into a Java EE container consists of a single persistence.xml file,
any number of mapping files, and any number of class files.
At deployment time the container is responsible for scanning the locations specified in Section 8.2 and
discovering the persistence.xml files and processing them.
JSR-338 Final Release
381
4/2/13
Oracle
Container and Provider Contracts for Deployment and BootstrappingJava Persistence 2.1, Final Release
Java EE Deployment
When the container finds a persistence.xml file, it must process the persistence unit definitions
that it contains. The container must validate the persistence.xml file against the
persistence_2_1.xsd, persistence_2_0.xsd, or persistence_1_0.xsd schema in
accordance with the version specified by the persistence.xml file and report any validation errors.
Provider or data source information not specified in the persistence.xml file must be provided at
deployment time or defaulted by the container. The container may optionally add any container-specific
properties to be passed to the provider when creating the entity manager factory for the persistence unit.
Once the container has read the persistence metadata, it determines the javax.persistence.spi.PersistenceProvider implementation class for each deployed named persistence
unit. The container then creates an instance of the PersistenceProvider implementation class for
each deployed named persistence unit and invokes the createContainerEntityManagerFactory method on that instance.
• The container must implement the PersistenceUnitInfo interface described in section
9.6 and pass the metadata—in the form of a PersistenceUnitInfo instance—to the persistence provider as part of this call.
• If a Bean Validation provider exists in the container environment and the valida-
tion-mode NONE is not specified, a ValidatorFactory instance must be made available by the container. The container is responsible for passing this ValidatorFactory
instance via the map that is passed as an argument to the createContainerEntityManagerFactory call. The map key used must be the standard property name javax.persistence.validation.factory.
• If CDI is enabled, a BeanManager instance must be made available by the container. The
container is responsible for passing this BeanManager instance via the map that is passed as
an argument to the createContainerEntityManagerFactory call. The map key
used must be the standard property name javax.persistence.bean.manager.
The EntityManagerFactory instance obtained as a result will be used by the container to create
container-managed entity managers. Only one EntityManagerFactory is permitted to be created for each
deployed persistence unit configuration. Any number of EntityManager instances may be created from
a given factory.
In a Java EE environment, the classes of the persistence unit should not be loaded by the application
class loader or any of its parent class loaders until after the entity manager factory for the persistence
unit has been created.
When a persistence unit is redeployed, the container should call the close method on the previous
EntityManagerFactory instance and call the createContainerEntityManagerFactory method again, with the required PersistenceUnitInfo metadata, to achieve the redeployment.
4/2/13
382
JSR-338 Final Release
Oracle
Bootstrapping in Java SE Environments
Java Persistence 2.1, Final ReleaseContainer and Provider Contracts for Deployment
9.2 Bootstrapping in Java SE Environments
In Java SE environments, the Persistence.createEntityManagerFactory method is used
by the application to create an entity manager factory[92].
A persistence provider implementation running in a Java SE environment should also act as a service
provider by supplying a service provider configuration file as described in the JAR File Specification
[6].
The provider configuration file serves to export the provider implementation class to the Persistence bootstrap class, positioning the provider as a candidate for backing named persistence units.
The provider supplies the provider configuration file by creating a text file named javax.persistence.spi.PersistenceProvider and placing it in the META-INF/services directory of
one of its JAR files. The contents of the file should be the name of the provider implementation class of
the javax.persistence.spi.PersistenceProvider interface.
Example:
A persistence vendor called ACME persistence products ships a JAR called acme.jar that contains
its persistence provider implementation. The JAR includes the provider configuration file.
acme.jar
META-INF/services/javax.persistence.spi.PersistenceProvider
com.acme.PersistenceProvider
…
The contents of the META-INF/services/javax.persistence.spi.PersistenceProvider file is nothing more than the name of the implementation class: com.acme.PersistenceProvider.
Persistence provider jars may be installed or made available in the same ways as other service providers, e.g. as extensions or added to the application classpath according to the guidelines in the JAR File
Specification.
The Persistence bootstrap class must locate all of the persistence providers using the PersistenceProviderResolver mechanism described in section 9.3 and call createEntityManagerFactory on them in turn until an appropriate backing provider returns an
EntityManagerFactory instance. A provider may deem itself as appropriate for the persistence
unit if any of the following are true:
• Its implementation class has been specified in the provider element for that persistence unit
in the persistence.xml file and has not been overridden by a different javax.persistence.provider property value included in the Map passed to the createEntityManagerFactory method.
[92] Use of these Java SE bootstrapping APIs may be supported in Java EE containers; however, support for such use is not required.
JSR-338 Final Release
383
4/2/13
Oracle
Container and Provider Contracts for Deployment and BootstrappingJava Persistence 2.1, Final ReleaseDetermining the Available Per-
• The javax.persistence.provider property was included in the Map passed to cre-
ateEntityManagerFactory and the value of the property is the provider’s implementation class.
• No provider was specified for the persistence unit in either the persistence.xml or the
property map.
If a provider does not qualify as the provider for the named persistence unit, it must return null when
createEntityManagerFactory is invoked on it.
9.2.1 Schema Generation
In Java SE environments, the Persistence.generateSchema method may be used by the application to cause schema generation to occur as a separate phase from entity manager factory creation.
In this case, the Persistence bootstrap class must locate all of the persistence providers using the
PersistenceProviderResolver mechanism described in section 9.3 and call generateSchema on them in turn until an appropriate backing provider returns true. A provider may deem
itself as appropriate for the persistence unit if any of the following are true:
• Its implementation class has been specified in the provider element for that persistence unit
in the persistence.xml file and has not been overridden by a different javax.persistence.provider property value included in the Map passed to the generateSchema method.
• The javax.persistence.provider property was included in the Map passed to generateSchema and the value of the property is the provider's implementation class.
• No provider was specified for the persistence unit in either the persistence.xml or the
property map.
If a provider does not qualify as the provider for the named persistence unit, it must return false when
generateSchema is invoked on it.
9.3 Determining the Available Persistence Providers
The PersistenceProviderResolver and PersistenceProviderResolverHolder
mechanism supports the dynamic discovery of persistence providers.[93]
The PersistenceProviderResolver instance is responsible for returning the list of providers
available in the environment.
[93] In dynamic environments (e.g., OSGi-based environments, containers based on dynamic kernels, etc.), the list of persistence providers may change.
4/2/13
384
JSR-338 Final Release
Oracle
Determining the Available Persistence Providers Java Persistence 2.1, Final ReleaseContainer and Provider Contracts for Deployment
The PersistenceProviderResolverHolder class holds the PersistenceProviderResolver instance that is in use. The implementation of PersistenceProviderResolverHolder must be threadsafe, but no guarantee is made against multiple threads setting the resolver.
The container is allowed to implement and set a specific PersistenceProviderResolver provided that it respects the PersistenceProviderResolver contract. The PersistenceProviderResolver instance to be used is set by the container using the
PersistenceProviderResolverHolder.setPersistenceProviderResolver
method.[94]
If no PersistenceProviderResolver is set, the PersistenceProviderResolverHolder must return a PersistenceProviderResolver that returns the providers whose persistence provider jars have been installed or made available as service providers or extensions. This default
PersistenceProviderResolver instance does not guarantee the order in which persistence providers are returned.
A PersistenceProviderResolver must be threadsafe.
The PersistenceProviderResolver.getPersistenceProviders() method must be
used to determine the list of available persistence providers.
The results of calling the PersistenceProviderResolverHolder.getPersistenceProviderResolver and the PersistenceProviderResolver.getPersistenceProviders methods must not be cached. In particular, the following methods must use the
PersistenceProviderResolver instance returned by the PersistenceProviderResolverHolder.getPersistenceProviderResolver method to determine the list of available providers:
• Persistence.createEntityManagerFactory(String)
• Persistence.createEntityManagerFactory(String, Map)
• PersistenceUtil.isLoaded(Object)
• PersistenceUtil.isLoaded(Object, String)
These methods must not cache the list of providers and must not cache the PersistenceProviderResolver instance.
Note that the PersistenceProviderResolver.getPersistenceProviders()
method can potentially be called many times. It is therefore recommended that the implementation of this method make use of caching.
Note that only a single PersistenceProviderResolver instance can be defined in a given
classloader hierarchy at a given time.
[94] If a custom PersistenceProviderResolver is needed in a JavaSE environment, it must be set before Persistence.createEntityManagerFactory is called. Note, however, that the setPersistenceProviderResolver method is not intended for general use, but rather is
aimed at containers maintaining a dynamic environment.
JSR-338 Final Release
385
4/2/13
Oracle
Container and Provider Contracts for Deployment and BootstrappingJava Persistence 2.1, Final ReleaseDetermining the Available Per-
9.3.1 PersistenceProviderResolver interface
package javax.persistence.spi;
import java.util.List;
/**
* Determine the list of persistence providers available in the
* runtime environment.
*
* Implementations must be thread-safe.
*
* Note that the getPersistenceProviders method can potentially
* be called many times: it is recommended that the implementation
* of this method make use of caching.
*/
public interface PersistenceProviderResolver {
/**
* Returns a list of the PersistenceProvider implementations
* available in the runtime environment.
*
* @return list of the persistence providers available
*
in the environment
*/
List<PersistenceProvider> getPersistenceProviders();
}
/**
* Clear cache of providers.
*/
void clearCachedProviders();
9.3.2 PersistenceProviderResolverHolder class
package javax.persistence.spi;
import java.util.List;
/**
* Holds the global PersistenceProviderResolver instance.
* If no PersistenceProviderResolver is set by the environment,
* the default PersistenceProviderResolver is used.
*
* Implementations must be thread-safe.
*/
public class PersistenceProviderResolverHolder {
/**
* Returns the current persistence provider resolver.
* @return persistence provider resolver in use
*/
public static PersistenceProviderResolver getPersistenceProviderResolver() {
...;
}
4/2/13
386
JSR-338 Final Release
Oracle
Schema Generation
Java Persistence 2.1, Final ReleaseContainer and Provider Contracts for Deployment
}
/**
* Defines the persistence provider resolver used.
* @param resolver PersistenceProviderResolver to be used
*/
public static void setPersistenceProviderResolver(
PersistenceProviderResolver resolver) {
...;
}
9.4 Schema Generation
In cases where a preconfigured database (or a “legacy” database) is not used or is not available, the Java
Persistence schema generation facility may be used to generate the tables and other database artifacts
required by the persistence application. Whether schema generation entails the creation of schemas
proper in the database is determined by the environment and the configuration of the schema generation
process, as described below.
Schema generation may happen either prior to application deployment or when the entity manager factory is created as part of the application deployment and initialization process.
• In Java EE environments, the container may call the PersistenceProvider gener-
ateSchema method separately from and/or prior to the creation of the entity manager factory
for the persistence unit, or the container may pass additional information to the createContainerEntityManagerFactory call to cause schema generation to happen as part of
the entity manager factory creation and application initialization process. The information
passed to these methods controls whether the generation occurs directly in the target database,
whether DDL scripts for schema generation are created, or both.
• In Java SE environments, the application may call the Persistence generateSchema
method separately from and/or prior to the creation of the entity manager factory or may pass
information to the createEntityManagerFactory method to cause schema generation
to occur as part of the entity manager factory creation.
The application may provide DDL scripts to be used for schema generation as described in Section
8.2.1.9. The application developer may package these scripts as part of the persistence unit or may specify strings corresponding to file URLs for the location of such scripts. In Java EE environments, such
scripts may be executed by the container, or the container may direct the persistence provider to execute
the scripts. In Java SE environments, the execution of the scripts is the responsibility of the persistence
provider. In the absence of the specification of scripts, schema generation, if requested, will be determined by the object/relational metadata of the persistence unit.
The following standard properties are defined for configuring the schema generation process. In Java
EE environments these properties are passed by the container in the Map argument to either the PersistenceProvider generateSchema method or the createContainerEntityManagerFactory method. In Java SE environments, they are passed in the Map argument to either the
Persistence generateSchema method or createEntityManagerFactory method.
JSR-338 Final Release
387
4/2/13
Oracle
Container and Provider Contracts for Deployment and BootstrappingJava Persistence 2.1, Final Release
Schema Generation
In Java EE environments, any strings corresponding to file URLs for script sources or targets must specify absolute paths (not relative). In Java EE environments, all source and target file locations must be
accessible to the application server deploying the persistence unit
• javax.persistence.schema-generation.database.action
The javax.persistence.schema-generation.database.action property
specifies the action to be taken by the persistence provider with regard to the database artifacts.
The values for this property are "none", "create", "drop-and-create", "drop". If
the javax.persistence.schema-generation.database.action property is
not specified, no schema generation actions must be taken on the database.
• javax.persistence.schema-generation.scripts.action
The javax.persistence.schema-generation.scripts.action property specifies which scripts are to be generated by the persistence provider. The values for this property
are "none", "create", "drop-and-create", "drop". A script will only be generated
if the script target is specified. If this property is not specified, no scripts will be generated.
• javax.persistence.schema-generation.create-source
The javax.persistence.schema-generation.create-source property specifies whether the creation of database artifacts is to occur on the basis of the object/relational
mapping metadata, DDL script, or a combination of the two. The values for this property are
"metadata", "script", "metadata-then-script", "script-then-metadata". If this property is not specified, and a script is specified by the javax.persistence.schema-generation.create-script-source property, the script (only)
will be used for schema generation; otherwise if this property is not specified, schema generation will occur on the basis of the object/relational mapping metadata (only). The "metadata-then-script" and "script-then-metadata" values specify that a
combination of metadata and script is to be used and the order in which this use is to occur. If
either of these values is specified and the resulting database actions are not disjoint, the results
are undefined and schema generation may fail.
• javax.persistence.schema-generation.drop-source
The javax.persistence.schema-generation.drop-source property specifies
whether the dropping of database artifacts is to occur on the basis of the object/relational mapping metadata, DDL script, or a combination of the two. The values for this property are
"metadata", "script", "metadata-then-script", "script-then-metadata". If this property is not specified, and a script is specified by the javax.persistence.schema-generation.drop-script-source property, the script (only) will
be used for the dropping of database artifacts; otherwise if this property is not specified, the
dropping of database artifacts will occur on the basis of the object/relational mapping metadata
(only). The "metadata-then-script" and "script-then-metadata" values
specify that a combination of metadata and script is to be used and the order in which this use
is to occur. If either of these values is specified and the resulting database actions are not disjoint, the results are undefined and the dropping of database artifacts may fail.
• javax.persistence.schema-generation.create-database-schemas
In Java EE environments, it is anticipated that the Java EE platform provider may wish to control the creation of database schemas rather than delegate this task to the persistence provider.
4/2/13
388
JSR-338 Final Release
Oracle
Schema Generation
Java Persistence 2.1, Final ReleaseContainer and Provider Contracts for Deployment
The javax.persistence.schema-generation.create-database-schemas
property specifies whether the persistence provider is to create the database schema(s) in addition to creating database objects such as tables, sequences, constraints, etc. The value of this
boolean property should be set to true if the persistence provider is to create schemas in the
database or to generate DDL that contains “CREATE SCHEMA” commands. If this property
is not supplied, the provider should not attempt to create database schemas. This property may
also be specified in Java SE environments.
• javax.persistence.schema-generation.scripts.create-target,
javax.persistence.schema-generation.scripts.drop-target
If scripts are to be generated, the target locations for the writing of these scripts must be specified.
The
javax.persistence.schema-generation.scripts.create-target
property specifies a java.IO.Writer configured for use by the persistence provider for
output of the DDL script or a string specifying the file URL for the DDL script. This property
should only be specified if scripts are to be generated.
The javax.persistence.schema-generation.scripts.drop-target property specifies a java.IO.Writer configured for use by the persistence provider for output
of the DDL script or a string specifying the file URL for the DDL script. This property should
only be specified if scripts are to be generated.
• javax.persistence.database-product-name,
javax.persistence.database-major-version,
javax.persistence.database-minor-version
If scripts are to be generated by the persistence provider and a connection to the target database
is not supplied, the javax.persistence.database-product-name property must
be specified. The value of this property should be the value returned for the target database by
the JDBC DatabaseMetaData method getDatabaseProductName. If sufficient
database version information is not included in the result of this method, the javax.persistence.database-major-version
and
javax.persistence.database-minor-version properties should be specified as needed. These should contain the
values returned by the JDBC getDatabaseMajorVersion and getDatabaseMinorVersion methods respectively.
• javax.persistence.schema-generation.create-script-source,
javax.persistence.schema-generation.drop-script-source
The javax.persistence.schema-generation.create-script-source and
javax.persistence.schema-generation.drop-script-source properties
are used for script execution. In Java EE container environments, it is generally expected that
the container will be responsible for executing DDL scripts, although the container is permitted to delegate this task to the persistence provider. If DDL scripts are to be used in Java SE
environments or if the Java EE container delegates the execution of scripts to the persistence
provider, these properties must be specified.
The javax.persistence.schema-generation.create-script-source property specifies a java.IO.Reader configured for reading of the DDL script or a string designating a file URL for the DDL script.
JSR-338 Final Release
389
4/2/13
Oracle
Container and Provider Contracts for Deployment and BootstrappingJava Persistence 2.1, Final Release Responsibilities of the Persis-
The javax.persistence.schema-generation.drop-script-source property
specifies a java.IO.Reader configured for reading of the DDL script or a string designating a file URL for the DDL script.
• javax.persistence.schema-generation.connection
The javax.persistence.schema-generation.connection property specifies
the JDBC connection to be used for schema generation. This is intended for use in Java EE
environments, where the platform provider may want to control the database privileges that are
available to the persistence provider. This connection is provided by the container, and should
be closed by the container when the schema generation request or entity manager factory creation completes. The connection provided must have credentials sufficient for the persistence
provider to carry out the requested actions. If this property is not specified, the persistence
provider should use the DataSource that has otherwise been provided.
9.4.1 Data Loading
Data loading, by means of the use of SQL scripts, may occur as part of the schema generation process
after the creation of the database artifacts or independently of schema generation. The specification of
the javax.persistence.sql-load-script-source controls whether data loading will
occur.
• javax.persistence.sql-load-script-source
In Java EE container environments, it is generally expected that the container will be responsible for executing data load scripts, although the container is permitted to delegate this task to
the persistence provider. If a load script is to be used in Java SE environments or if the Java
EE container delegates the execution of the load script to the persistence provider, this property
must be specified.
The javax.persistence.sql-load-script-source property specifies a
java.IO.Reader configured for reading of the SQL load script for database initialization
or a string designating a file URL for the script.
9.5 Responsibilities of the Persistence Provider
The persistence provider must implement the PersistenceProvider SPI.
In Java EE environments, the persistence provider must process the metadata that is passed to it at the
time createContainerEntityManagerFactory method is called and create an instance of
EntityManagerFactory using the PersistenceUnitInfo metadata for the factory. The factory is then returned to the container.
In Java SE environments, the persistence provider must validate the persistence.xml file against
the persistence schema that corresponds to the version specified by the persistence.xml file
and report any validation errors.
The persistence provider processes the metadata annotations on the managed classes of the persistence
unit.
4/2/13
390
JSR-338 Final Release
Oracle
Responsibilities of the Persistence Provider
Java Persistence 2.1, Final ReleaseContainer and Provider Contracts for Deployment
When the entity manager factory for a persistence unit is created, it is the responsibility of the persistence provider to initialize the state of the metamodel classes of the persistence unit.
When the persistence provider obtains an object/relational mapping file, it processes the definitions that
it contains. The persistence provider must validate any object/relational mapping files against the
object/relational mapping schema version specified by the object/relational mapping file and report any
validation errors. The object relational mapping file must specify the object/relational mapping schema
that it is written against by indicating the version element.
In Java SE environments, the application can pass the ValidatorFactory instance via the map that
is passed as an argument to the Persistence.createEntityManagerFactory call. The map
key used must be the standard property name javax.persistence.validation.factory. If
no ValidatorFactory instance is provided by the application, and if a Bean Validation provider is
present in the classpath, the persistence provider must instantiate the ValidatorFactory using the
default bootstrapping approach as defined by the Bean Validation specification [8], namely Validation.buildDefaultValidatorFactory().
9.5.1 javax.persistence.spi.PersistenceProvider
The interface javax.persistence.spi.PersistenceProvider must be implemented by
the persistence provider.
It is invoked by the container in Java EE environments and by the javax.persistence.Persistence class in Java SE environments. The javax.persistence.spi.PersistenceProvider implementation is not intended to be used by the application.
The PersistenceProvider implementation class must have a public no-arg constructor.
package javax.persistence.spi;
import javax.persistence.EntityManagerFactory;
import java.util.Map;
/**
* Interface implemented by the persistence provider.
*
* It is invoked by the container in Java EE environments and
* by the Persistence class in Java SE environments to
* create an EntityManagerFactory and/or to cause schema generation
* to occur.
*/
public interface PersistenceProvider {
/**
* Called by Persistence class when an EntityManagerFactory
* is to be created.
*
* @param emName the name of the persistence unit
* @param map a Map of properties for use by the
* persistence provider. These properties may be used to
* override the values of the corresponding elements in
* the persistence.xml file or specify values for
* properties not specified in the persistence.xml
JSR-338 Final Release
391
4/2/13
Oracle
Container and Provider Contracts for Deployment and BootstrappingJava Persistence 2.1, Final Release Responsibilities of the Persis-
* (and may be null if no properties are specified).
* @return EntityManagerFactory for the persistence unit,
* or null if the provider is not the right provider
*/
public EntityManagerFactory createEntityManagerFactory(
String emName, Map map);
/**
* Called by the container when an EntityManagerFactory
* is to be created.
*
* @param info metadata for use by the persistence provider
* @param map a Map of integration-level properties for use
* by the persistence provider (may be null if no properties
* are specified). These properties may include properties to
* control schema generation.
* If a Bean Validation provider is present in the classpath,
* the container must pass the ValidatorFactory instance in
* the map with the key "javax.persistence.validation.factory".
* If the containing archive is a bean archive, the container
* must pass the BeanManager instance in the map with the key
* "javax.persistence.bean.manager".
* @return EntityManagerFactory for the persistence unit
* specified by the metadata
*/
public EntityManagerFactory createContainerEntityManagerFactory(
PersistenceUnitInfo info, Map map);
/**
* Create database schemas and/or tables and/or create DDL
* scripts as determined by the supplied properties.
*
* Called by the container when schema generation is to
* occur as a separate phase from creation of the entity
* manager factory.
*
* @param info metadata for use by the persistence provider
* @param map properties for schema generation; these
*
may also include provider-specific properties
* @throws PersistenceException if insufficient or inconsistent
*
configuration information is provided or if schema
*
generation otherwise fails.
*/
public void generateSchema(PersistenceUnitInfo info, Map map);
/**
* Create database schemas and/or tables and/or create DDL
* scripts as determined by the supplied properties.
* Called by the Persistence class when schema generation is to
* occur as a separate phase from creation of the entity
* manager factory.
* @param persistenceUnitName the name of the persistence unit
* @param map properties for schema generation; these may
*
also contain provider-specific properties. The
*
value of these properties override any values that
*
may have been configured elsewhere.
* @return true if schema was generated, otherwise false
* @throws PersistenceException if insufficient or inconsistent
*
configuration information is provided or if schema
4/2/13
392
JSR-338 Final Release
Oracle
Responsibilities of the Persistence Provider
Java Persistence 2.1, Final ReleaseContainer and Provider Contracts for Deployment
*
generation otherwise fails.
*/
public boolean generateSchema(String persistenceUnitName,
Map map);
}
/**
* Return the utility interface implemented by the persistence
* provider.
* @return ProviderUtil interface
*/
public ProviderUtil getProviderUtil();
The properties used in the createEntityManagerFactory method in Java SE environments are
described further in section 9.7 below.
9.5.2 javax.persistence.spi.ProviderUtil
The ProviderUtil interface is invoked by the PersistenceUtil implementation to determine
the load status of an entity or entity attribute. It is not intended to be invoked by the application.
package javax.persistence.spi;
/**
* Utility interface implemented by the persistence provider.
* This interface is invoked by the PersistenceUtil implementation
* to determine the load status of an entity or entity attribute.
*/
public interface ProviderUtil {
/**
* If the provider determines that the entity has been provided
* by itself and that the state of the specified attribute has
* been loaded, this method returns LoadState.LOADED.
* If the provider determines that the entity has been provided
* by itself and that either entity attributes with FetchType
* EAGER have not been loaded or that the state of the specified
* attribute has not been loaded, this methods returns
* LoadState.NOT_LOADED.
* If a provider cannot determine the load state, this method
* returns LoadState.UNKNOWN.
* The provider's implementation of this method must not obtain
* a reference to an attribute value, as this could trigger the
* loading of entity state if the entity has been provided by a
* different provider.
* @param entity
* @param attributeName name of attribute whose load status is
*
to be determined
* @return load status of the attribute
*/
public LoadState isLoadedWithoutReference(
Object entity, String attributeName);
JSR-338 Final Release
393
4/2/13
Oracle
Container and Provider Contracts for Deployment and BootstrappingJava Persistence 2.1, Final Release Responsibilities of the Persis-
/**
* If the provider determines that the entity has been provided
* by itself and that the state of the specified attribute has
* been loaded, this method returns LoadState.LOADED.
* If a provider determines that the entity has been provided
* by itself and that either the entity attributes with FetchType
* EAGER have not been loaded or that the state of the specified
* attribute has not been loaded, this method returns
* return LoadState.NOT_LOADED.
* If the provider cannot determine the load state, this method
* returns LoadState.UNKNOWN.
* The provider's implementation of this method is permitted to
* obtain a reference to the attribute value. (This access is
* safe because providers which might trigger the loading of the
* attribute state will have already been determined by
* isLoadedWithoutReference. )
* @param entity
* @param attributeName name of attribute whose load status is
*
to be determined
* @return load status of the attribute
*/
public LoadState isLoadedWithReference(
Object entity, String attributeName);
}
4/2/13
/**
* If the provider determines that the entity has been provided
* by itself and that the state of all attributes for which
* FetchType EAGER has been specified have been loaded, this
* method returns LoadState.LOADED.
* If the provider determines that the entity has been provided
* by itself and that not all attributes with FetchType EAGER
* have been loaded, this method returns LoadState.NOT_LOADED.
* If the provider cannot determine if the entity has been
* provided by itself, this method returns LoadState.UNKNOWN.
* The provider's implementation of this method must not obtain
* a reference to any attribute value, as this could trigger the
* loading of entity state if the entity has been provided by a
* different provider.
* @param entity whose loaded status is to be determined
* @return load status of the entity
*/
public LoadState isLoaded(Object entity);
394
JSR-338 Final Release
Oracle
Responsibilities of the Persistence Provider
Java Persistence 2.1, Final ReleaseContainer and Provider Contracts for Deployment
package javax.persistence.spi;
public enum LoadState {
/**
* the state of the element is known to have been loaded
*/
LOADED,
/**
* the state of the element is known not to have been loaded
*/
NOT_LOADED,
}
JSR-338 Final Release
/**
* the load state of the element cannot be determined
*/
UNKNOWN
395
4/2/13
Oracle
Container and Provider Contracts for Deployment and BootstrappingJava Persistence 2.1, Final Releasejavax.persistence.spi.Persisten-
9.6 javax.persistence.spi.PersistenceUnitInfo Interface
package javax.persistence.spi;
import
import
import
import
import
import
javax.sql.DataSource;
java.util.List;
java.util.Properties;
java.net.URL;
javax.persistence.SharedCacheMode;
javax.persistence.ValidationMode;
/**
* Interface implemented by the container and used by the
* persistence provider when creating an EntityManagerFactory.
*/
public interface PersistenceUnitInfo {
/**
* Returns the name of the persistence unit. Corresponds to
* the name attribute in the persistence.xml file.
* @return the name of the persistence unit
*/
public String getPersistenceUnitName();
/**
* Returns the fully qualified name of the persistence provider
* implementation class. Corresponds to the provider element in
* the persistence.xml file.
* @return the fully qualified name of the persistence provider
* implementation class
*/
public String getPersistenceProviderClassName();
/**
* Returns the transaction type of the entity managers created by
* the EntityManagerFactory. The transaction type corresponds to
* the transaction-type attribute in the persistence.xml file.
* @return transaction type of the entity managers created
* by the EntityManagerFactory
*/
public PersistenceUnitTransactionType getTransactionType();
/**
* Returns the JTA-enabled data source to be used by the
* persistence provider. The data source corresponds to the
* jta-data-source element in the persistence.xml file or is
* provided at deployment or by the container.
* @return the JTA-enabled data source to be used by the
* persistence provider
*/
public DataSource getJtaDataSource();
4/2/13
396
JSR-338 Final Release
Oracle
javax.persistence.spi.PersistenceUnitInfo InterfaceJava Persistence 2.1, Final Release
Container and Provider Contracts for Deploy-
/**
* Returns the non-JTA-enabled data source to be used by the
* persistence provider for accessing data outside a JTA
* transaction. The data source corresponds to the named
* non-jta-data-source element in the persistence.xml file or
* provided at deployment or by the container.
* @return the non-JTA-enabled data source to be used by the
* persistence provider for accessing data outside a JTA
* transaction
*/
public DataSource getNonJtaDataSource();
/**
* Returns the list of the names of the mapping files that the
* persistence provider must load to determine the mappings for
* the entity classes. The mapping files must be in the standard
* XML mapping format, be uniquely named and be resource-loadable
* from the application classpath. Each mapping file name
* corresponds to a mapping-file element in the
* persistence.xml file.
* @return the list of mapping file names that the persistence
* provider must load to determine the mappings for the entity
* classes
*/
public List<String> getMappingFileNames();
/**
* Returns a list of URLs for the jar files or exploded jar
* file directories that the persistence provider must examine
* for managed classes of the persistence unit. Each URL
* corresponds to a jar-file element in the
* persistence.xml file. A URL will either be a file: URL
* referring to a jar file or referring to a directory
* that contains an exploded jar file, or some other URL from
* which an InputStream in jar format can be obtained.
* @return a list of URL objects referring to jar files or
* directories
*/
public List<URL> getJarFileUrls();
/**
* Returns the URL for the jar file or directory that is the
* root of the persistence unit. (If the persistence unit is
* rooted in the WEB-INF/classes directory, this will be the
* URL of that directory.)
* The URL will either be a file: URL referring to a jar file
* or referring to a directory that contains an exploded jar
* file, or some other URL from which an InputStream in jar
* format can be obtained.
* @return a URL referring to a jar file or directory
*/
public URL getPersistenceUnitRootUrl();
JSR-338 Final Release
397
4/2/13
Oracle
Container and Provider Contracts for Deployment and BootstrappingJava Persistence 2.1, Final Releasejavax.persistence.spi.Persisten-
/**
* Returns the list of the names of the classes that the
* persistence provider must add to its set of managed
* classes. Each name corresponds to a named class element in the
* persistence.xml file.
* @return the list of the names of the classes that the
* persistence provider must add to its set of managed
* classes
*/
public List<String> getManagedClassNames();
/**
* Returns whether classes in the root of the persistence unit
* that have not been explicitly listed are to be included in the
* set of managed classes. This value corresponds to the
* exclude-unlisted-classes element in the persistence.xml file.
* @return whether classes in the root of the persistence
* unit that have not been explicitly listed are to be
* included in the set of managed classes
*/
public boolean excludeUnlistedClasses();
/**
* Returns the specification of how the provider must use
* a second-level cache for the persistence unit.
* The result of this method corresponds to the shared-cache-mode
* element in the persistence.xml file.
* @return the second-level cache mode that must be used by the
* provider for the persistence unit
*/
public SharedCacheMode getSharedCacheMode();
/**
* Returns the validation mode to be used by the persistence
* provider for the persistence unit. The validation mode
* corresponds to the validation-mode element in the
* persistence.xml file.
* @return the validation mode to be used by the
* persistence provider for the persistence unit
*/
public ValidationMode getValidationMode();
/**
* Returns a properties object. Each property corresponds to a
* property element in the persistence.xml file.
* @return Properties object
*/
public Properties getProperties();
/**
* Returns the schema version of the persistence.xml file.
* @return persistence.xml schema version
*/
public String getPersistenceXMLSchemaVersion();
4/2/13
398
JSR-338 Final Release
Oracle
javax.persistence.spi.PersistenceUnitInfo InterfaceJava Persistence 2.1, Final Release
Container and Provider Contracts for Deploy-
/**
* Returns ClassLoader that the provider may use to load any
* classes, resources, or open URLs.
* @return ClassLoader that the provider may use to load any
* classes, resources, or open URLs
*/
public ClassLoader getClassLoader();
/**
* Add a transformer supplied by the provider that will be
* called for every new class definition or class redefinition
* that gets loaded by the loader returned by the
* PersistenceUnitInfo.getClassLoader method. The transformer
* has no effect on the result returned by the
* PersistenceUnitInfo.getNewTempClassLoader method.
* Classes are only transformed once within the same classloading
* scope, regardless of how many persistence units they may be
* a part of.
* @param transformer
provider-supplied transformer that the
* container invokes at class-(re)definition time
*/
public void addTransformer(ClassTransformer transformer);
}
/**
* Return a new instance of a ClassLoader that the provider may
* use to temporarily load any classes, resources, or open
* URLs. The scope and classpath of this loader is exactly the
* same as that of the loader returned by
* PersistenceUnitInfo.getClassLoader. None of the classes loaded
* by this class loader will be visible to application
* components. The provider may only use this ClassLoader within
* the scope of the createContainerEntityManagerFactory call.
* @return temporary ClassLoader with same visibility as current
* loader
*/
public ClassLoader getNewTempClassLoader();
The enum javax.persistence.spi.PersistenceUnitTransactionType defines
whether the entity managers created by the factory will be JTA or resource-local entity managers.
package javax.persistence.spi;
public enum PersistenceUnitTransactionType {
JTA,
RESOURCE_LOCAL
}
The enum javax.persistence.SharedCacheMode defines the use of caching. The persistence.xml shared-cache-mode element has no default value. The getSharedCacheMode
method must return UNSPECIFIED if the shared-cache-mode element has not been specified for
the persistence unit.
JSR-338 Final Release
399
4/2/13
Oracle
Container and Provider Contracts for Deployment and BootstrappingJava Persistence 2.1, Final Releasejavax.persistence.spi.Persisten-
package javax.persistence;
public enum SharedCacheMode {
ALL,
NONE,
ENABLE_SELECTIVE,
DISABLE_SELECTIVE,
UNSPECIFIED
}
The enum javax.persistence.ValidationMode defines the validation mode.
package javax.persistence;
public enum ValidationMode {
AUTO,
CALLBACK,
NONE
}
9.6.1 javax.persistence.spi.ClassTransformer Interface
The javax.persistence.spi.ClassTransformer interface is implemented by a persistence
provider that wants to transform entities and managed classes at class load time or at class redefinition
time.
package javax.persistence.spi;
import java.security.ProtectionDomain;
import java.lang.instrument.IllegalClassFormatException;
/**
* A persistence provider supplies an instance of this
* interface to the PersistenceUnitInfo.addTransformer
* method. The supplied transformer instance will get
* called to transform entity class files when they are
* loaded or redefined. The transformation occurs before
* the class is defined by the JVM.
*/
public interface ClassTransformer {
/**
* Invoked when a class is being loaded or redefined.
* The implementation of this method may transform the
* supplied class file and return a new replacement class
* file.
*
* @param loader the defining loader of the class to be
*
transformed, may be null if the bootstrap loader
* @param className the name of the class in the internal form
*
of fully qualified class and interface names
* @param classBeingRedefined if this is a redefine, the
*
class being redefined, otherwise null
* @param protectionDomain the protection domain of the
*
class being defined or redefined
4/2/13
400
JSR-338 Final Release
Oracle
javax.persistence.Persistence Class
}
Java Persistence 2.1, Final ReleaseContainer and Provider Contracts for Deployment
* @param classfileBuffer the input byte buffer in class
*
file format - must not be modified
* @return a well-formed class file buffer (the result of
*
the transform), or null if no transform is performed
* @throws IllegalClassFormatException if the input does
*
not represent a well-formed class file
*/
byte[] transform(ClassLoader loader,
String className,
Class<?> classBeingRedefined,
ProtectionDomain protectionDomain,
byte[] classfileBuffer)
throws IllegalClassFormatException;
9.7 javax.persistence.Persistence Class
The Persistence class is used to obtain an EntityManagerFactory instance in Java SE environments. It may also be used for schema generation— i.e., to create database schemas and/or tables
and/or to create DDL scripts.
The Persistence class is available in a Java EE container environment as well; however, support for
the Java SE bootstrapping APIs is not required in container environments.
The Persistence class is used to obtain a PersistenceUtil instance in both Java EE and Java
SE environments.
JSR-338 Final Release
401
4/2/13
Oracle
Container and Provider Contracts for Deployment and BootstrappingJava Persistence 2.1, Final Release javax.persistence.Persistence
package javax.persistence;
import java.util.*;
...
/**
* Provider-independent class
*
* Class that is used to obtain an EntityManagerFactory in Java SE
* environments. It may also be used to cause schema generation to
* occur.
*
* Class that is used to obtain an instance of PersistenceUtil in
* Java EE and Java SE environments.
*/
public class Persistence {
/**
* Create and return an EntityManagerFactory for the
* named persistence unit.
*
* Use of this method is not required to be supported in
* Java EE container environments.
*
* @param persistenceUnitName the name of the persistence unit
* @return the factory that creates EntityManagers configured
* according to the specified persistence unit
*/
public static EntityManagerFactory createEntityManagerFactory(
String persistenceUnitName) {...}
/**
* Create and return an EntityManagerFactory for the
* named persistence unit using the given properties.
*
* Use of this method is not required to be supported in
* Java EE container environments.
*
* @param persistenceUnitName the name of the persistence unit
* @param props additional properties to use when creating the
* factory. These properties may include properties to control
* schema generation. The values of these properties override
* any values that may have been configured elsewhere.
* @return the factory that creates EntityManagers configured
* according to the specified persistence unit
*/
public static EntityManagerFactory createEntityManagerFactory(
String persistenceUnitName, Map properties) {...};
/**
* Create database schemas and/or tables and/or create DDL
* scripts as determined by the supplied properties
*
* Called when schema generation is to occur as a separate
* phase from creation of the entity manager factory.
* @param persistenceUnitName the name of the persistence unit
* @param map properties for schema generation; these may also
*
contain provider-specific properties. The values of
*
these properties override any values that may have
4/2/13
402
JSR-338 Final Release
Oracle
javax.persistence.Persistence Class
Java Persistence 2.1, Final ReleaseContainer and Provider Contracts for Deployment
*
been configured elsewhere.
* @throws PersistenceException if insufficient or inconsistent
*
configuration information is provided or if schema
*
generation otherwise fails.
*/
public static void generateSchema(String persistenceUnitName,
Map properties);
/*
* Return PersistenceUtil instance
*/
public static PersistenceUtil getPersistenceUtil() {...}
}
...
The properties argument passed to the createEntityManagerFactory method is used to
specify both standard and vendor-specific properties and hints intended for use in creating the entity
manager factory.
The following properties correspond to the elements and properties in the persistence.xml file.
When any of these properties are specified in the Map parameter passed to the createEntityManagerFactory method, their values override the values of the corresponding elements and properties
in the persistence.xml file for the named persistence unit. They also override any defaults that the
persistence provider might have applied.
• javax.persistence.lock.timeout — integer value in milliseconds for pessimistic
lock timeout or string corresponding to integer value. This corresponds to the property of the
same name in the persistence.xml, and is a hint only. See section 3.4.4.3.
• javax.persistence.query.timeout — integer value in milliseconds for query timeout or string corresponding to integer value. This corresponds to the property of the same
name in the persistence.xml, and is a hint only. See section 3.10.10.
• javax.persistence.provider — string corresponding to the provider element in
the persistence.xml. See section 8.2.1.4.
• javax.persistence.transactionType — string corresponding to the transaction-type attribute in the persistence.xml. See section 8.2.1.2.
• javax.persistence.jtaDataSource
—
string
corresponding
jta-data-source element in the persistence.xml. See section 8.2.1.5.
to
• javax.persistence.nonJtaDataSource
— string corresponding to
non-jta-data-source element in the persistence.xml. See section 8.2.1.5.
• javax.persistence.sharedCache.mode
— string corresponding
shared-cache-mode element in the persistence.xml. See section 8.2.1.7
to
the
the
the
• javax.persistence.validation.mode — string corresponding to the validation-mode element in the persistence.xml. The value is "auto", "callback", or
"none". See sections 8.2.1.8 and 3.6.1.1.
JSR-338 Final Release
403
4/2/13
Oracle
Container and Provider Contracts for Deployment and BootstrappingJava Persistence 2.1, Final Release javax.persistence.Persistence
• javax.persistence.validation.group.pre-persist — string corresponding
to the javax.persistence.validation.group.pre-persist property in the
persistence.xml. See sections 8.2.1.9 and 3.6.1.2.
• javax.persistence.validation.group.pre-update — string corresponding to
the javax.persistence.validation.group.pre-update property in the persistence.xml. See sections 8.2.1.9 and 3.6.1.2.
• javax.persistence.validation.group.pre-remove — string corresponding to
the javax.persistence.validation.group.pre-remove property in the persistence.xml. See sections 8.2.1.9 and 3.6.1.2.
• javax.persistence.schema-generation.create-script-source — string
corresponding
to
the
javax.persistence.schema-generation.create-script-source property in the persistence.xml. See section 8.2.1.9.
• javax.persistence.schema-generation.drop-script-source —
string
corresponding
to
the
javax.persistence.schema-generation.drop-script-source property in the persistence.xml. See section 8.2.1.9.
• javax.persistence.sql-load-script-source — string corresponding to the
javax.persistence.sql-load-script-source
tence.xml. See section 8.2.1.9.
property in the persis-
• javax.persistence.schema-generation.database.action — string corresponding to the javax.persistence.schema-generation.database.action
property in the persistence.xml. See section 8.2.1.9.
• javax.persistence.schema-generation.scripts.action — string corresponding to the javax.persistence.schema-generation.scripts.action
property in the persistence.xml. See section 8.2.1.9.
• javax.persistence.schema-generation.create-source — string corresponding to the javax.persistence.schema-generation.create-source
property in the persistence.xml. See section 8.2.1.9.
• javax.persistence.schema-generation.drop-source — string corresponding to the javax.persistence.schema-generation.drop-source property in
the persistence.xml. See section 8.2.1.9.
• javax.persistence.schema-generation.scripts.create-target —
string
corresponding
to
the
javax.persistence.schema-generation.scripts.create-target property in the persistence.xml. See section
8.2.1.9.
• javax.persistence.schema-generation.scripts.drop-target — string
corresponding
to
the
javax.persistence.schema-generation.scripts.drop-target property in the persistence.xml. See section
8.2.1.9.
4/2/13
404
JSR-338 Final Release
Oracle
PersistenceUtil Interface
Java Persistence 2.1, Final ReleaseContainer and Provider Contracts for Deployment
The following additional standard properties are defined by this specification for the configuration of
the entity manager factory:
• javax.persistence.jdbc.driver — value is the fully qualified name of the driver
class.
• javax.persistence.jdbc.url — string corresponding to the driver-specific URL.
• javax.persistence.jdbc.user — value is the username used by database connection.
• javax.persistence.jdbc.password — value is the password for database connection validation.
• javax.persistence.dataSource
— value is instance of javax.sql.DataSource to be used for the specified persistence unit.
• javax.persistence.validation.factory — value is instance of javax.validation.ValidatorFactory.
Any number of vendor-specific properties may also be included in the map. If a persistence provider
does not recognize a property (other than a property defined by this specification), the provider must
ignore it.
Vendors should use vendor namespaces for properties (e.g., com.acme.persistence.logging).
Entries that make use of the namespace javax.persistence and its subnamespaces must not be
used for vendor-specific information. The namespace javax.persistence is reserved for use by
this specification.
9.8 PersistenceUtil Interface
This interface is used to determine load state. The semantics of the methods of this interface are defined
in section 9.8.1 below.
package javax.persistence;
/**
* Utility interface between the application and the persistence
* provider(s).
*
* The PersistenceUtil interface instance obtained from the
* Persistence class is used to determine the load state of an
* entity or entity attribute regardless of which persistence
* provider in the environment created the entity.
*/
public interface PersistenceUtil {
/**
* Determine the load state of a given persistent attribute.
* @param entity containing the attribute
JSR-338 Final Release
405
4/2/13
Oracle
Container and Provider Contracts for Deployment and BootstrappingJava Persistence 2.1, Final Release
PersistenceUtil Interface
* @param attributeName name of attribute whose load state is
*
to be determined
* @return false if entity's state has not been loaded or
* if the attribute state has not been loaded, else true
*/
public boolean isLoaded(Object entity, String attributeName);
}
/**
* Determine the load state of an entity.
* This method can be used to determine the load state
* of an entity passed as a reference. An entity is
* considered loaded if all attributes for which FetchType
* EAGER has been specified have been loaded.
* The isLoaded(Object, String) method should be used to
* determine the load state of an attribute.
* Not doing so might lead to unintended loading of state.
* @param entity whose load state is to be determined
* @return false if the entity has not been loaded, else true
*/
public boolean isLoaded(Object entity);
9.8.1 Contracts for Determining the Load State of an Entity or Entity Attribute
The implementation of the PersistenceUtil.isLoaded(Object) method must determine the
list of persistence providers available in the runtime environment[95] and call the ProviderUtil.isLoaded(Object) method on each of them until either:
• one provider returns LoadState.LOADED. In this case PersistenceUtil.isLoaded
returns true.
• one
provider returns LoadState.NOT_LOADED.
ceUtil.isLoaded returns false.
In
this
case
Persisten-
• all providers return LoadState.UNKNOWN. In this case PersistenceUtil.isLoaded
returns true.
If the PersistenceUtil implementation determines that only a single provider is available in the
environment, it is permitted to use provider-specific methods to determine the result of
isLoaded(Object) as long as the semantics defined in section 3.2.9 are observed.
The implementation of the PersistenceUtil.isLoaded(Object,String) method must
determine the list of persistence providers available in the environment and call the ProviderUtil.isLoadedWithoutReference method on each of them until either:
• one provider returns LoadState.LOADED. In this case PersistenceUtil.isLoaded
returns true.
• one
provider returns LoadState.NOT_LOADED.
ceUtil.isLoaded returns false.
In
this
case
Persisten-
[95] The determining of the persistence providers that are available is discussed in section 9.3.
4/2/13
406
JSR-338 Final Release
Oracle
PersistenceUtil Interface
Java Persistence 2.1, Final ReleaseContainer and Provider Contracts for Deployment
• all providers return LoadState.UNKNOWN.
In this case, the PersistenceUtil.isLoaded method then calls ProviderUtil.isLoadedWithReference
on each of the providers until:
• one provider returns LoadState.LOADED.
In this case Persisten-
ceUtil.isLoaded return true.
• one provider returns LoadState.NOT_LOADED. In this case, PersistenceUtil.isLoaded returns false.
• all providers return LoadState.UNKNOWN.
In this case, Persisten-
ceUtil.isLoaded returns true.
If the PersistenceUtil implementation determines that only a single provider is available in the
environment, it is permitted to use provider specific methods to determine the result of
isLoaded(Object, String) as long as the semantics defined in section 3.2.9 are observed.
NOTE: The rationale for splitting the determination of load state between the methods isLoadedWithoutReference and isLoadedWithReference is the following.
• It is assumed that the provider that loaded the entity is present in the environment.
• Providers that use bytecode enhancement don't need to access an attribute reference to determine its load state, and can determine if the entity has been provided by them.
• By first querying all providers using bytecode enhancement, it is insured that no attribute will
be loaded by side effect.
• Proxy-based providers do need to access an attribute reference to determine load state, but
will not trigger attribute loading as a side effect.
• If no provider recognizes an entity as provided by it, it is assumed to be an object that is not
instrumented and is considered loaded.
JSR-338 Final Release
407
4/2/13
Oracle
Container and Provider Contracts for Deployment and BootstrappingJava Persistence 2.1, Final Release
4/2/13
408
PersistenceUtil Interface
JSR-338 Final Release
Oracle
Entity
Java Persistence 2.1, Final Release
Chapter 10
Metadata Annotations
Metadata Annotations
This chapter and chapter 11 define the metadata annotations introduced by this specification.
The XML schema defined in chapter 12 provides an alternative to the use of metadata annotations.
These annotations and types are in the package javax.persistence.
10.1 Entity
The Entity annotation specifies that the class is an entity. This annotation is applied to the entity
class.
The name annotation element specifies the entity name. If the name element is not specified, the entity
name defaults to the unqualified name of the entity class. This name is used to refer to the entity in queries.
@Documented @Target(TYPE) @Retention(RUNTIME)
public @interface Entity {
String name() default "";
}
JSR-338 Final Release
409
4/2/13
Oracle
Metadata Annotations
Java Persistence 2.1, Final Release
Callback Annotations
10.2 Callback Annotations
The EntityListeners annotation specifies the callback listener classes to be used for an entity or
mapped superclass. The EntityListeners annotation may be applied to an entity class or mapped
superclass.
@Target({TYPE}) @Retention(RUNTIME)
public @interface EntityListeners {
Class[] value();
}
The ExcludeSuperclassListeners annotation specifies that the invocation of superclass listeners is to be excluded for the entity class (or mapped superclass) and its subclasses.
@Target({TYPE}) @Retention(RUNTIME)
public @interface ExcludeSuperclassListeners {
}
The ExcludeDefaultListeners annotation specifies that the invocation of default listeners is to
be excluded for the entity class (or mapped superclass) and its subclasses.
@Target({TYPE}) @Retention(RUNTIME)
public @interface ExcludeDefaultListeners {
}
The following annotations are used to specify callback methods for the corresponding lifecycle events.
These annotations may be applied to methods of an entity class, of a mapped superclass, or of an entity
listener class.
@Target({METHOD}) @Retention(RUNTIME)
public @interface PrePersist {}
@Target({METHOD}) @Retention(RUNTIME)
public @interface PostPersist {}
@Target({METHOD}) @Retention(RUNTIME)
public @interface PreRemove {}
@Target({METHOD}) @Retention(RUNTIME)
public @interface PostRemove {}
@Target({METHOD}) @Retention(RUNTIME)
public @interface PreUpdate {}
@Target({METHOD}) @Retention(RUNTIME)
public @interface PostUpdate {}
@Target({METHOD}) @Retention(RUNTIME)
public @interface PostLoad {}
4/2/13
410
JSR-338 Final Release
Oracle
EntityGraph Annotations
Java Persistence 2.1, Final Release
Metadata Annotations
10.3 EntityGraph Annotations
10.3.1 NamedEntityGraph and NamedEntityGraphs Annotations
The NamedEntityGraph annotation is used to define a named entity graph. The entity graph may
be retrieved by name using the EntityManagerFactory interface. The entity graph may be used
to specify the path and boundaries for find operations or queries.
The NamedEntityGraph annotation must be applied to the entity class that forms the root of the corresponding graph of entities.
The name element is used to refer to the entity graph. It defaults to the entity name of the root entity to
which the annotation is applied. Entity graph names must be unique within the persistence unit.
The attributeNodes element lists attributes of the annotated entity class that are to be included in
the entity graph.
The includeAllAttributes element specifies that all attributes of the annotated entity class are
to be included in the entity graph. An attributeNode element may still be used in conjunction with
this element to specify a subgraph for the attribute.
The subgraphs element specifies a list of subgraphs, further specifying attributes that are managed
types. These subgraphs are referenced by name from NamedAttributeNode definitions.
The subclassSubgraphs element specifies a list of subgraphs that add additional attributes for
subclasses of the root entity to which the annotation is applied.
The NamedEntityGraphs annotation is used to specify multiple named entity graphs for the entity
to which it is applied.
@Target({TYPE}) @Retention(RUNTIME)
public @interface NamedEntityGraph {
String name() default "";
NamedAttributeNode[] attributeNodes() default {};
boolean includeAllAttributes() default false;
NamedSubgraph[] subgraphs() default {};
NamedSubgraph[] subclassSubgraphs() default {};
}
@Target({TYPE}) @Retention(RUNTIME)
public @interface NamedEntityGraphs{
NamedEntityGraph[] value();
}
10.3.2 NamedAttributeNode Annotation
The NamedAttributeNode annotation is used to specify an attribute node of within an entity graph
or subgraph.
JSR-338 Final Release
411
4/2/13
Oracle
Metadata Annotations
Java Persistence 2.1, Final Release
EntityGraph Annotations
The value element specifies the name of the corresponding attribute.
The subgraph element is used to refer to a NamedSubgraph specification that further characterizes
an attribute node corresponding to a managed type (entity or embeddable). The value of the subgraph element must correspond to the name used for the subgraph in the NamedSubgraph element.
If the referenced attribute is an entity which has entity subclasses, there may be more than one NamedSubgraph element with this name, and the subgraph element is considered to refer to all of these.
The keySubgraph element is used to refer to a NamedSubgraph specification that further characterizes an attribute node corresponding to the key of a Map-valued attribute. The value of the the keySubgraph element must correspond to the name used for the subgraph in the NamedSubgraph
element. If the referenced attribute is an entity which has entity subclasses, there may be more than one
NamedSubgraph element with this name, and the keySubgraph element is considered to refer to
all of these.
@Target({}) @Retention(RUNTIME)
public @interface NamedAttributeNode {
String value();
String subgraph() default "";
String keySubgraph() default "";
}
10.3.3 NamedSubgraph Annotation
The NamedSubgraph annotation is used to further define an attribute node. It is referenced by its
name from the subgraph or keySubgraph element of a NamedAttributeNode element.
The name element is the name used to reference the subgraph from a NamedAttributeNode definition. In the case of entity inheritance, multiple subgraph elements have the same name.
The type element must be specified when the subgraph corresponds to a subclass of the entity type
corresponding to the referencing attribute node.
The attributeNodes element lists attributes of the class that must be included. If the subgraph corresponds to a subclass of the class referenced by the corresponding attribute node, only subclass-specific attributes are listed.
@Target({}) @Retention(RUNTIME)
public @interface NamedSubgraph {
String name();
Class type() default void.class;
NamedAttributeNode[] attributeNodes();
}
4/2/13
412
JSR-338 Final Release
Oracle
Annotations for Queries
Java Persistence 2.1, Final Release
Metadata Annotations
10.4 Annotations for Queries
10.4.1 NamedQuery Annotation
The NamedQuery annotation is used to specify a named query in the Java Persistence query language.
The name element is used to refer to the query when using the EntityManager methods that create
query objects.
The query element must specify a query string in the Java Persistence query language.
The lockMode element specifies a lock mode for the results returned by the query. If a lock mode
other than NONE is specified, the query must be executed within a transaction and the persistence context joined to the transaction.
The hints elements may be used to specify query properties and hints. Properties defined by this specification must be observed by the provider; hints defined by this specification should be observed by the
provider when possible. Vendor-specific hints that are not recognized by a provider must be ignored.
The NamedQuery and NamedQueries annotations can be applied to an entity or mapped superclass.
@Target({TYPE}) @Retention(RUNTIME)
public @interface NamedQuery {
String name();
String query();
LockModeType lockMode() default NONE;
QueryHint[] hints() default {};
}
@Target({}) @Retention(RUNTIME)
public @interface QueryHint {
String name();
String value();
}
@Target({TYPE}) @Retention(RUNTIME)
public @interface NamedQueries {
NamedQuery[] value ();
}
10.4.2 NamedNativeQuery Annotation
The NamedNativeQuery annotation is used to specify a native SQL named query.
The name element is used to refer to the query when using the EntityManager methods that create
query objects.
The query element specifies the native query.
JSR-338 Final Release
413
4/2/13
Oracle
Metadata Annotations
Java Persistence 2.1, Final Release
Annotations for Queries
The resultClass element refers to the class of the result; the value of the resultSetMapping
element is the name of a SqlResultSetMapping specification, as defined in metadata.
The hints elements may be used to specify query properties and hints. Hints defined by this specification should be observed by the provider when possible. Vendor-specific hints that are not recognized by
a provider must be ignored.
The NamedNativeQuery and NamedNativeQueries annotations can be applied to an entity or
mapped superclass.
@Target({TYPE}) @Retention(RUNTIME)
public @interface NamedNativeQuery {
String name();
String query();
QueryHint[] hints() default {};
Class resultClass() default void.class;
String resultSetMapping() default "";
}
@Target({TYPE}) @Retention(RUNTIME)
public @interface NamedNativeQueries {
NamedNativeQuery[] value ();
}
10.4.3 NamedStoredProcedureQuery Annotation
The NamedStoredProcedureQuery annotation is used to specify a stored procedure, its parameters, and its result type.
The name element is the name that is passed as an argument to the createNamedStoredProcedureQuery method to create an executable StoredProcedureQuery object.
The procedureName element is the name of the stored procedure in the database.
The parameters of the stored procedure are specified by the parameters element. All parameters
must be specified in the order in which they occur in the parameter list of the stored procedure.
The resultClasses element refers to the class (or classes) that are used to map the results. The
resultSetMappings element names one or more result set mappings, as defined by the SqlResultSetMapping annotation.
If there are multiple result sets, it is assumed that they will be mapped using the same mechanism—e.g.,
either all via a set of result class mappings or all via a set of result set mappings. The order of the specification of these mappings must be the same as the order in which the result sets will be returned by the
stored procedure invocation. If the stored procedure returns one or more result sets and no resultClasses or resultSetMappings element is specified, any result set will be returned as a list of
type Object[]. The combining of different strategies for the mapping of stored procedure result sets
is undefined.
4/2/13
414
JSR-338 Final Release
Oracle
Annotations for Queries
Java Persistence 2.1, Final Release
Metadata Annotations
The hints element may be used to specify query properties and hints. Properties defined by this specification must be observed by the provider. Vendor-specific hints that are not recognized by a provider
must be ignored.
The NamedStoredProcedureQuery and NamedStoredProcedureQueries annotations can
be applied to an entity or mapped superclass.
@Target(TYPE) @Retention(RUNTIME)
public @interface NamedStoredProcedureQuery{
String name();
String procedureName();
StoredProcedureParameter[] parameters() default {};
Class[] resultClasses() default {};
String[] resultSetMappings() default {};
QueryHint[] hints() default {};
}
@Target(TYPE) @Retention(RUNTIME)
public @interface NamedStoredProcedureQueries {
NamedStoredProcedureQuery [] value;
}
All parameters of a named stored procedure query must be specified using the StoredProcedureParameter annotation. The name element refers to the name of the parameter as defined by the
stored procedure in the database. If a parameter name is not specified, it is assumed that the stored procedure uses positional parameters. The mode element specifies whether the parameter is an IN,
INOUT, OUT, or REF_CURSOR parameter. REF_CURSOR parameters are used by some databases to
return result sets from stored procedures. The type element refers to the JDBC type for the parameter.
@Target({}) @Retention(RUNTIME)
public @interface StoredProcedureParameter {
String name() default "";
ParameterMode mode() default ParameterMode.IN;
Class type();
}
public enum ParameterMode {
IN,
INOUT,
OUT,
REF_CURSOR
}
JSR-338 Final Release
415
4/2/13
Oracle
Metadata Annotations
Java Persistence 2.1, Final Release
Annotations for Queries
10.4.4 Annotations for SQL Result Set Mappings
The SqlResultSetMapping annotation is used to specify the mapping of the result of a native SQL
query or stored procedure.
@Target({TYPE}) @Retention(RUNTIME)
public @interface SqlResultSetMapping {
String name();
EntityResult[] entities() default {};
ConstructorResult[] classes() default {};
ColumnResult[] columns() default {};
}
@Target({TYPE}) @Retention(RUNTIME)
public @interface SqlResultSetMappings {
SqlResultSetMapping[] value();
}
The name element is the name given to the result set mapping, and is used to refer to it in the methods
of the Query and StoredProcedureQuery APIs. The entities, classes, and columns elements are used to specify the mapping to entities, constructors, and to scalar values respectively.
@Target({}) @Retention(RUNTIME)
public @interface EntityResult {
Class entityClass();
FieldResult[] fields() default {};
String discriminatorColumn() default "";
}
The entityClass element specifies the class of the result.
The fields element is used to map the columns specified in the SELECT list of the query to the properties or fields of the entity class.
The discriminatorColumn element is used to specify the column name (or alias) of the column in
the SELECT list that is used to determine the type of the entity instance.
@Target({}) @Retention(RUNTIME)
public @interface FieldResult {
String name();
String column();
}
The name element is the name of the persistent field or property of the class.
The column element specifies the name of the corresponding column in the SELECT list—i.e., column alias, if applicable.
@Target(value={}) @Retention(RUNTIME)
public @interface ConstructorResult {
Class targetClass();
ColumnResult[] columns();
}
The targetClass element specifies the class whose constructor is to be invoked.
4/2/13
416
JSR-338 Final Release
Oracle
References to EntityManager and EntityManagerFactoryJava Persistence 2.1, Final Release
Metadata Annotations
The columns element specifies the mapping of columns in the SELECT list to the arguments of the
intended constructor.
@Target({}) @Retention(RUNTIME)
public @interface ColumnResult {
String name();
Class type() default void.class;
}
The name element specifies the name of the column in the SELECT list.
The type element specifies the Java type to which the column type is to be mapped. If the type element is not specified, the default JDBC type mapping for the column will be used.
10.5 References to EntityManager and EntityManagerFactory
These annotations are used to express dependencies on entity managers and entity manager factories.
10.5.1 PersistenceContext Annotation
The PersistenceContext annotation is used to express a dependency on a container-managed
entity manager and its associated persistence context.
The name element refers to the name by which the entity manager is to be accessed in the environment
referencing context, and is not needed when dependency injection is used.
The optional unitName element refers to the name of the persistence unit. If the unitName element
is specified, the persistence unit for the entity manager that is accessible in JNDI must have the same
name.
The type element specifies whether a transaction-scoped or extended persistence context is to be used.
If the type element is not specified, a transaction-scoped persistence context is used.
The synchronizationType element specifies whether the persistence context is always automatically synchronized with the current transaction or whether the persistence context must be explicitly
joined to the current transaction by means of the EntityManager joinTransaction method.
The optional properties element may be used to specify properties for the container or persistence
provider. Properties defined by this specification must be observed by the provider. Vendor specific
properties may be included in the set of properties, and are passed to the persistence provider by the
container when the entity manager is created. Properties that are not recognized by a vendor must be
ignored.
JSR-338 Final Release
417
4/2/13
Oracle
Metadata Annotations
Java Persistence 2.1, Final ReleaseReferences to EntityManager and EntityManager-
@Target({TYPE, METHOD, FIELD}) @Retention(RUNTIME)
public @interface PersistenceContext {
String name() default "";
String unitName() default "";
PersistenceContextType type() default TRANSACTION;
SynchronizationType synchronization() default SYNCHRONIZED;
PersistenceProperty[] properties() default {};
}
public enum PersistenceContextType {
TRANSACTION,
EXTENDED
}
public enum SynchronizationType {
SYNCHRONIZED,
UNSYNCHRONIZED
}
@Target({}) @Retention(RUNTIME)
public @interface PersistenceProperty {
String name();
String value();
}
The PersistenceContexts annotation declares one or more PersistenceContext annotations. It is used to express a dependency on multiple persistence contexts[96].
@Target({TYPE}) @Retention(RUNTIME)
public @interface PersistenceContexts {
PersistenceContext[] value();
}
10.5.2 PersistenceUnit Annotation
The PersistenceUnit annotation is used to express a dependency on an entity manager factory and
its associated persistence unit.
The name element refers to the name by which the entity manager factory is to be accessed in the environment referencing context, and is not needed when dependency injection is used.
The optional unitName element refers to the name of the persistence unit as defined in the persistence.xml file. If the unitName element is specified, the persistence unit for the entity manager
factory that is accessible in JNDI must have the same name.
@Target({TYPE, METHOD, FIELD}) @Retention(RUNTIME)
public @interface PersistenceUnit {
String name() default "";
String unitName() default "";
}
[96] A dependency on ultiple persistence contexts may be needed, for example, when multiple persistence units are used.
4/2/13
418
JSR-338 Final Release
Oracle
Annotations for Type Converter Classes
Java Persistence 2.1, Final Release
Metadata Annotations
The PersistenceUnits annotation declares one or more PersistenceUnit annotations. It is
used to express a dependency on multiple persistence units[97].
@Target(TYPE) @Retention(RUNTIME)
public @interface PersistenceUnits {
PersistenceUnit[] value();
}
10.6 Annotations for Type Converter Classes
The Converter annotation specifies that the annotated class is a converter and defines its scope. A
converter class must be annotated with the Converter annotation or defined in the XML descriptor as
a converter.
@Target({TYPE}) @Retention(RUNTIME)
public @interface Converter {
boolean autoApply() default false;
}
If the autoApply element is specified as true, the persistence provider must automatically apply the
converter to all mapped attributes of the specified target type for all entities in the persistence unit
except for attributes for which conversion is overridden by means of the Convert annotation (or XML
equivalent). The Convert annotation is described in section 11.1.10.
In determining whether a converter is applicable to an attribute, the provider must treat primitive types
and wrapper types as equivalent.
Note that Id attributes, version attributes, relationship attributes, and attributes explicitly annotated as
Enumerated or Temporal (or designated as such via XML) will not be converted.
If autoApply is false, only those attributes of the target type for which the Convert annotation
(or corresponding XML element) has been specified will be converted.
Note that if autoApply is true, the Convert annotation may be used to override or disable
auto-apply conversion on a per-attribute basis.
If there is more than one converter defined for the same target type, the Convert annotation should be
used to explicitly specify which converter to use.
[97] Multiple persistence units may be needed, for example, when mapping to multiple databases.
JSR-338 Final Release
419
4/2/13
Oracle
Metadata Annotations
4/2/13
Java Persistence 2.1, Final Release
420
Annotations for Type Converter Classes
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Ch apt er 11
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
Metadata for Object/Relational Mapping
The object/relational mapping metadata is part of the application domain model contract. It expresses
requirements and expectations on the part of the application as to the mapping of the entities and relationships of the application domain to a database. Queries (and, in particular, SQL queries) written
against the database schema that corresponds to the application domain model are dependent upon the
mappings expressed by means of the object/relational mapping metadata. The implementation of this
specification must assume this application dependency upon the object/relational mapping metadata and
insure that the semantics and requirements expressed by that mapping are observed.
The use of object/relational mapping metadata to control schema generation is specified in section 11.2.
11.1 Annotations for Object/Relational Mapping
These annotations and types are in the package javax.persistence.
XML metadata may be used as an alternative to these annotations, or to override or augment annotations, as described in Chapter 12.
JSR-338 Final Release
421
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
11.1.1 Access Annotation
The Access annotation is used to specify an access type to be applied to an entity class, mapped superclass, or embeddable class, or to a specific attribute of such a class.
@Target({TYPE, METHOD, FIELD}) @Retention(RUNTIME)
public @interface Access {
AccessType value();
}
public enum AccessType {
FIELD,
PROPERTY
}
Table 4 lists the annotation elements that may be specified for the Access annotation.
Table 4
Access Annotation Elements
Type
Name
Description
AccessType
value
(Required) The access type to be applied to the class or
attribute.
Default
11.1.2 AssociationOverride Annotation
The AssociationOverride annotation is used to override a mapping for an entity relationship.
The AssociationOverride annotation may be applied to an entity that extends a mapped superclass to override a relationship mapping defined by the mapped superclass. If the AssociationOverride annotation is not specified, the association is mapped the same as in the original mapping.
When used to override a mapping defined by a mapped superclass, the AssociationOverride
annotation is applied to the entity class.
The AssociationOverride annotation may be used to override a relationship mapping from an
embeddable within an entity to another entity when the embeddable is on the owning side of the relationship. When used to override a relationship mapping defined by an embeddable class (including an
embeddable class embedded within another embeddable class), the AssociationOverride annotation is applied to the field or property containing the embeddable.
When the AssociationOverride annotation is used to override a relationship mapping from an
embeddable class, the name element specifies the referencing relationship field or property within the
embeddable class. To override mappings at multiple levels of embedding, a dot (".") notation syntax
must be used in the name element to indicate an attribute within an embedded attribute. The value of
each identifier used with the dot notation is the name of the respective embedded field or property.
When the AssociationOverride annotation is applied to override the mappings of an embeddable
class used as a map value, "value." must be used to prefix the name of the attribute within the
embeddable class that is being overridden in order to specify it as part of the map value.[98]
4/2/13
422
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
If the relationship mapping is a foreign key mapping, the joinColumns element of the AssociationOverride annotation is used. If the relationship mapping uses a join table, the joinTable
element of the AssociationOverride element must be specified to override the mapping of the
join table and/or its join columns.[99]
The joinColumns element refers to the table for the class that contains the annotation.
The foreignKey element is used to specify or control the generation of a foreign key constraint for
the columns corresponding to the joinColumns element when table generation is in effect. If both
this element and the foreignKey element of any of the joinColumns elements are specified, the
behavior is undefined.
@Target({TYPE, METHOD, FIELD}) @Retention(RUNTIME)
public @interface AssociationOverride {
String name();
JoinColumn[] joinColumns() default {};
ForeignKey foreignKey() default @ForeignKey(PROVIDER_DEFAULT);
JoinTable joinTable() default @JoinTable;
}
Table 5 lists the annotation elements that may be specified for the AssociationOverride annotation.
Table 5
AssociationOverride Annotation Elements
Type
Name
Description
Default
String
name
(Required) The name of the relationship property
whose mapping is being overridden if property-based
access is being used, or the name of the relationship
field if field-based access is used.
JoinColumn[]
joinColumns
The join column(s) being mapped to the persistent
attribute(s). The joinColumns element must be specified if a foreign key mapping is used in the overriding
of the mapping of the relationship. The joinColumns
element must not be specified if a join table is used in
the overriding of the mapping of the relationship
ForeignKey
foreignKey
(Optional) The foreign key constraint specification for
the join columns. This is used only if table generation
is in effect.
Provider’s default
JoinTable
joinTable
The join table that maps the relationship. The joinTable element must be specified if a join table is used
in the overriding of the mapping of the relationship.
The joinTable element must not be specified if a foreign key mapping is used in the overriding of the mapping of the relationship.
.
[98] The use of map keys that contain embeddables that reference entities is not permitted.
[99] Note that either the joinColumns element or the joinTable element of the AssociationOverride annotation is specified for overriding a given relationship (but never both).
JSR-338 Final Release
423
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
Example 1:
@MappedSuperclass
public class Employee {
@Id protected Integer id;
@Version protected Integer version;
@ManyToOne
protected Address address;
}
public
public
public
public
Integer getId() { ... }
void setId(Integer id) { ... }
Address getAddress() { ... }
void setAddress(Address address) { ... }
@Entity
@AssociationOverride(name="address",
[email protected](name="ADDR_ID"))
public class PartTimeEmployee extends Employee {
// address field mapping overridden to ADDR_ID foreign key
@Column(name="WAGE")
protected Float hourlyWage;
public Float getHourlyWage() { ... }
public void setHourlyWage(Float wage) { ... }
}
Example 2: Overriding of the mapping for the phoneNumbers relationship defined in the ContactInfo embeddable class.
@Entity
public class Employee {
@Id int id;
@AssociationOverride(
name="phoneNumbers",
[email protected](
name="EMPPHONES",
[email protected](name="EMP"),
[email protected](name="PHONE")
)
)
@Embedded ContactInfo contactInfo;
...
}
@Embeddable
public class ContactInfo {
@ManyToOne Address address; // Unidirectional
@ManyToMany(targetEntity=PhoneNumber.class) List phoneNumbers;
}
@Entity
public class PhoneNumber {
@Id int number;
@ManyToMany(mappedBy="contactInfo.phoneNumbers")
Collection<Employee> employees;
}
4/2/13
424
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
11.1.3 AssociationOverrides Annotation
The mappings of multiple relationship properties or fields may be overridden. The AssociationOverrides annotation is used for this purpose.
@Target({TYPE, METHOD, FIELD}) @Retention(RUNTIME)
public @interface AssociationOverrides {
AssociationOverride[] value();
}
Table 6 lists the annotation elements that may be specified for the AssociationOverrides annotation.
Table 6
AssociationOverrides Annotation Elements
Type
Name
Description
AssociationOverride[]
value
(Required) The association override mappings that are to
be applied to the relationship field or property.
Default
Example:
@MappedSuperclass
public class Employee {
@Id protected Integer id;
@Version protected Integer version;
@ManyToOne protected Address address;
@OneToOne protected Locker locker;
public
public
public
public
public
public
Integer getId() { ... }
void setId(Integer id) { ... }
Address getAddress() { ... }
void setAddress(Address address) { ... }
Locker getLocker() { ... }
void setLocker(Locker locker) { ... }
}
@Entity
@AssociationOverrides({
@AssociationOverride(name="address",
[email protected]("ADDR_ID")),
@AssociationOverride(name="locker",
[email protected]("LCKR_ID"))})
public PartTimeEmployee { ... }
JSR-338 Final Release
425
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
11.1.4 AttributeOverride Annotation
The AttributeOverride annotation is used to override the mapping of a Basic (whether explicit
or default) property or field or Id property or field.
The AttributeOverride annotation may be applied to an entity that extends a mapped superclass
or to an embedded field or property to override a Basic mapping or Id mapping defined by the
mapped superclass or embeddable class (or embeddable class of one of its attributes).
The AttributeOverride annotation may be applied to an element collection containing instances
of an embeddable class or to a map collection whose key and/or value is an embeddable class. When the
AttributeOverride annotation is applied to a map, "key." or "value." must be used to prefix the name of the attribute that is being overridden in order to specify it as part of the map key or map
value.
To override mappings at multiple levels of embedding, a dot (".") notation form must be used in the
name element to indicate an attribute within an embedded attribute. The value of each identifier used
with the dot notation is the name of the respective embedded field or property.
If the AttributeOverride annotation is not specified, the column is mapped the same as in the
original mapping.
Table 7 lists the annotation elements that may be specified for the AttributeOverride annotation.
The column element refers to the table for the class that contains the annotation.
@Target({TYPE, METHOD, FIELD}) @Retention(RUNTIME)
public @interface AttributeOverride {
String name();
Column column();
}
Table 7
4/2/13
AttributeOverride Annotation Elements
Type
Name
Description
Default
String
name
(Required) The name of the property whose mapping is being
overridden if property-based access is being used, or the name of
the field if field-based access is used.
Column
column
(Required) The column that is being mapped to the persistent
attribute. The mapping type will remain the same as is defined in
the embeddable class or mapped superclass.
426
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
Example 1:
@MappedSuperclass
public class Employee {
@Id protected Integer id;
@Version protected Integer version;
protected String address;
}
public
public
public
public
Integer getId() { ... }
void setId(Integer id) { ... }
String getAddress() { ... }
void setAddress(String address) { ... }
@Entity
@AttributeOverride(name="address", [email protected](name="ADDR"))
public class PartTimeEmployee extends Employee {
// address field mapping overridden to ADDR
protected Float wage();
public Float getHourlyWage() { ... }
public void setHourlyWage(Float wage) { ... }
}
Example 2:
@Embeddable
protected
protected
protected
@Embedded
}
public class Address {
String street;
String city;
String state;
protected Zipcode zipcode;
@Embeddable public class Zipcode {
protected String zip;
protected String plusFour;
}
@Entity public class Customer {
@Id protected Integer id;
protected String name;
@AttributeOverrides({
@AttributeOverride(name="state",
[email protected](name="ADDR_STATE")),
@AttributeOverride(name="zipcode.zip",
column= @Column(name="ADDR_ZIP"))
})
@Embedded protected Address address;
...
}
JSR-338 Final Release
427
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
Example 3:
@Entity
public class PropertyRecord {
@EmbeddedId PropertyOwner owner;
}
@AttributeOverrides({
@AttributeOverride(name="key.street",
[email protected](name="STREET_NAME")),
@AttributeOverride(name="value.size",
[email protected](name="SQUARE_FEET")),
@AttributeOverride(name="value.tax",
[email protected](name="ASSESSMENT"))
})
@ElementCollection
Map<Address, PropertyInfo> parcels;
@Embeddable public class PropertyInfo {
Integer parcelNumber;
Integer size;
BigDecimal tax;
}
11.1.5 AttributeOverrides Annotation
The mappings of multiple properties or fields may be overridden. The AttributeOverrides annotation is used for this purpose.
@Target({TYPE, METHOD, FIELD}) @Retention(RUNTIME)
public @interface AttributeOverrides {
AttributeOverride[] value();
}
Table 8 lists the annotation elements that may be specified for the AttributeOverrides annotation.
Table 8
4/2/13
AttributeOverrides Annotation Elements
Type
Name
Description
AttributeOverride[]
value
(Required) The AttributeOverride mappings that are to be
applied to the field or property.
428
Default
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
Example:
@Embedded
@AttributeOverrides({
@AttributeOverride(name="startDate",
[email protected](name="EMP_START")),
@AttributeOverride(name="endDate",
[email protected](name="EMP_END"))
})
public EmploymentPeriod getEmploymentPeriod() { ... }
11.1.6 Basic Annotation
The Basic annotation is the simplest type of mapping to a database column. The Basic annotation
can be applied to a persistent property or instance variable of any of the following types: Java primitive
types, wrappers of the primitive types, java.lang.String, java.math.BigInteger,
java.math.BigDecimal, java.util.Date, java.util.Calendar, java.sql.Date,
java.sql.Time, java.sql.Timestamp, byte[], Byte[], char[], Character[],
enums, and any other type that implements Serializable. As described in Section 2.8, the use of
the Basic annotation is optional for persistent fields and properties of these types. If the Basic annotation is not specified for such a field or property, the default values of the Basic annotation will apply.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface Basic {
FetchType fetch() default EAGER;
boolean optional() default true;
}
Table 9 lists the annotation elements that may be specified for the Basic annotation and their default
values.
The FetchType enum defines strategies for fetching data from the database:
public enum FetchType { LAZY, EAGER };
The EAGER strategy is a requirement on the persistence provider runtime that data must be eagerly
fetched. The LAZY strategy is a hint to the persistence provider runtime that data should be fetched
lazily when it is first accessed. The implementation is permitted to eagerly fetch data for which the
LAZY strategy hint has been specified. In particular, lazy fetching might only be available for Basic
mappings for which property-based access is used.
The optional element is a hint as to whether the value of the field or property may be null. It is disregarded for primitive types.
JSR-338 Final Release
429
4/2/13
Oracle
Metadata for Object/Relational Mapping
Table 9
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
Basic Annotation Elements
Type
Name
Description
Default
FetchType
fetch
(Optional) Whether the value of the field or property
should be lazily loaded or must be eagerly fetched. The
EAGER strategy is a requirement on the persistence provider runtime that the value must be eagerly fetched. The
LAZY strategy is a hint to the persistence provider runtime.
EAGER
boolean
optional
(Optional) Whether the value of the field or property may
be null. This is a hint and is disregarded for primitive
types; it may be used in schema generation.
true
Example 1:
@Basic
protected String name;
Example 2:
@Basic(fetch=LAZY)
protected String getName() { return name; }
11.1.7 Cacheable Annotation
The Cacheable annotation specifies whether an entity should be cached if caching is enabled when
the value of the persistence.xml shared-cache-mode element is ENABLE_SELECTIVE or
DISABLE_SELECTIVE. The value of the Cacheable annotation is inherited by subclasses; it can be
overridden by specifying Cacheable on a subclass.
@Target({TYPE}) @Retention(RUNTIME)
public @interface Cacheable {
boolean value() default true;
}
Cacheable(false) means that the entity and its state must not be cached by the provider.
If the shared-cache-mode element is not specified in the persistence.xml file and the
javax.persistence.sharedCache.mode property is not specified when the entity manager
factory for the persistence unit is created, the semantics of the Cacheable annotation are undefined.
Table 10
4/2/13
Cacheable Annotation Elements
Type
Name
Description
Default
boolean
value
(Optional) Whether or not the entity should be cached.
true
430
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
11.1.8 CollectionTable Annotation
The CollectionTable annotation is used in the mapping of collections of basic or embeddable
types. The CollectionTable annotation specifies the table that is used for the mapping of the collection and is specified on the collection-valued field or property.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface CollectionTable {
String name() default "";
String catalog() default "";
String schema() default "";
JoinColumn[] joinColumns() default {};
ForeignKey foreignKey() default @ForeignKey(PROVIDER_DEFAULT);
UniqueConstraint[] uniqueConstraints() default {};
Index[] indexes() default {};
}
By default, the columns of the collection table that correspond to the embeddable class or basic type are
derived from the attributes of the embeddable class or from the basic type according to the default values of the Column annotation, as described in Section 11.1.9. In the case of a basic type, the column
name is derived from the name of the collection-valued field or property. In the case of an embeddable
class, the column names are derived from the field or property names of the embeddable class.
To override the default properties of the column used for a basic type, the Column annotation is used
on the collection-valued attribute in addition to the ElementCollection annotation. The value of
the table element of the Column annotation defaults to the name of the collection table.
To override these defaults for an embeddable class, the AttributeOverride and/or AttributeOverrides annotations must be used in addition to the ElementCollection annotation. The
value of the table element of the Column annotation used in the AttributeOverride annotation defaults to the name of the collection table. If the embeddable class contains references to other
entities, the default values for the columns corresponding to those references may be overridden by
means of the AssociationOverride and/or AssociationOverrides annotations.
The foreignKey element is used to specify or control the generation of a foreign key constraint for
the columns corresponding to the joinColumns element when table generation is in effect. If both
this element and the foreignKey element of any of the joinColumns elements are specified, the
behavior is undefined. If no foreignKey annotation element is specified in either location, the persistence provider's default foreign key strategy will apply.
If the CollectionTable annotation is missing, the default values of the CollectionTable
annotation elements apply.
Table 11 lists the annotation elements that may be specified for the CollectionTable annotation
and their default values.
JSR-338 Final Release
431
4/2/13
Oracle
Metadata for Object/Relational Mapping
Table 11
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
CollectionTable Annotation Elements
Type
Name
Description
Default
String
name
(Optional) The name of the collection table.
The concatenation of the name of
the containing entity and the
name of the collection attribute,
separated by an underscore.
String
catalog
(Optional) The catalog of the table.
Default catalog.
String
schema
(Optional) The schema of the table.
Default schema for user.
JoinColumn[]
joinColumns
(Optional) The foreign key columns of the collection table which
reference the primary table of the
entity.
(Default only applies if a single
join column is used.) The same
defaults as for JoinColumn (i.e.,
the concatenation of the following: the name of the entity; "_";
the name of the referenced primary key column.) However, if
there is more than one join column, a JoinColumn annotation
must be specified for each join
column using the JoinColumns
annotation. Both the name and
the referencedColumnName elements must be specified in each
such JoinColumn annotation.
ForeignKey
foreignKey
(Optional) The foreign key constraint specification for the join columns. This is used only if table
generation is in effect.
Provider’s default
UniqueConstraint[]
uniqueConstraints
(Optional) Unique constraints that
are to be placed on the table. These
are only used if table generation is
in effect.
No additional constraints
Index[]
indexes
(Optional) Indexes for the table.
These are only used if table generation is in effect.
No additional indexes
Example:
@Embeddable
protected
protected
protected
...
}
4/2/13
public
String
String
String
class Address {
street;
city;
state;
432
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
@Entity public class Person {
@Id protected String ssn;
protected String name;
protected Address home;
...
@ElementCollection // use default table (PERSON_NICKNAMES)
@Column(name="name", length=50)
protected Set<String> nickNames = new HashSet();
...
}
@Entity public class WealthyPerson extends Person {
@ElementCollection
@CollectionTable(name="HOMES") // use default join column name
@AttributeOverrides({
@AttributeOverride(name="street",
[email protected](name="HOME_STREET")),
@AttributeOverride(name="city",
[email protected](name="HOME_CITY")),
@AttributeOverride(name="state",
[email protected](name="HOME_STATE"))
})
protected Set<Address> vacationHomes = new HashSet();
...
}
11.1.9 Column Annotation
The Column annotation is used to specify a mapped column for a persistent property or field.
Table 12 lists the annotation elements that may be specified for the Column annotation and their
default values.
If no Column annotation is specified, the default values in Table 12 apply.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface Column {
String name() default "";
boolean unique() default false;
boolean nullable() default true;
boolean insertable() default true;
boolean updatable() default true;
String columnDefinition() default "";
String table() default "";
int length() default 255;
int precision() default 0; // decimal precision
int scale() default 0; // decimal scale
}
JSR-338 Final Release
433
4/2/13
Oracle
Metadata for Object/Relational Mapping
Table 12
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
Column Annotation Elements
Type
Name
Description
Default
String
name
(Optional) The name of the column.
The property or field
name.
boolean
unique
(Optional) Whether the column is a unique key. This
is a shortcut for the UniqueConstraint annotation at
the table level and is useful for when the unique key
constraint corresponds to only a single column. This
constraint applies in addition to any constraint
entailed by primary key mapping and to constraints
specified at the table level.
false
boolean
nullable
(Optional) Whether the database column is nullable.
true
boolean
insertable
(Optional) Whether the column is included in SQL
INSERT statements generated by the persistence
provider.
true
boolean
updatable
(Optional) Whether the column is included in SQL
UPDATE statements generated by the persistence
provider.
true
String
columnDefinition
(Optional) The SQL fragment that is used when generating the DDL for the column.
Generated SQL to create a column of the
inferred type.
String
table
(Optional) The name of the table that contains the
column. If absent the column is assumed to be in the
primary table for the mapped object.
Column is in primary
table.
int
length
(Optional) The column length. (Applies only if a
string-valued column is used.)
255
int
precision
(Optional) The precision for a decimal (exact
numeric) column. (Applies only if a decimal column
is used.)
0 (Value must be set by
developer.)
int
scale
(Optional) The scale for a decimal (exact numeric)
column. (Applies only if a decimal column is used.)
0
Example 1:
@Column(name="DESC", nullable=false, length=512)
public String getDescription() { return description; }
Example 2:
@Column(name="DESC",
columnDefinition="CLOB NOT NULL",
table="EMP_DETAIL")
@Lob
public String getDescription() { return description; }
4/2/13
434
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
Example 3:
@Column(name="ORDER_COST", updatable=false, precision=12, scale=2)
public BigDecimal getCost() { return cost; }
11.1.10 Convert Annotation
The Convert annotation is applied directly to an attribute of an entity, mapped superclass, or
embeddable class to specify conversion of a Basic attribute or to override the use of a converter that has
been specified as autoApply=true. When persistent properties are used, the Convert annotation
is applied to the getter method. It is not necessary to use the Basic annotation or corresponding XML
element to specify the basic type
The Convert annotation may be applied to an entity that extends a mapped superclass to specify or
override the conversion mapping for an inherited basic attribute.
@Target({METHOD, FIELD, TYPE}) @Retention(RUNTIME)
public @interface Convert {
Class converter() default void.class;
String attributeName() default "";
boolean disableConversion() default false;
}
Table 13 lists the annotation elements that may be specified for the Convert annotation.
Table 13
Convert Annotation Elements
Type
Name
Description
Default
Class
converter
(Optional) The converter to be applied.
No converter
String
attributeName
(Optional) The name of the attribute to convert. Must be
specified unless the Convert annotation is applied to an
attribute of basic type or to an element collection of basic
type. Must not be specified otherwise.
The basic attribute
or basic element collection attribute to
which the annotation
is applied
boolean
disableConversion
(Optional) Whether conversion of the attribute is to be disabled.
false
The converter element is used to specify the converter that is to be applied. If an autoApply converter is applicable to the given field or property, the converter specified by the converter element
will be applied instead.
The disableConversion element specifies that any applicable autoApply converter must not be
applied.
The behavior is undefined if neither the converter element nor the disableConversion element has been specified.
JSR-338 Final Release
435
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
The Convert annotation should not be used to specify conversion of the following: Id attributes
(including the attributes of embedded ids and derived identities), version attributes, relationship
attributes, and attributes explicitly annotated (or designated via XML) as Enumerated or Temporal. Applications that specify such conversions will not be portable.
The Convert annotation may be applied to a basic attribute or to an element collection of basic type
(in which case the converter is applied to the elements of the collection). In these cases, the
attributeName element must not be specified.
The Convert annotation may be applied to an embedded attribute or to a map collection attribute
whose key or value is of embeddable type (in which case the converter is applied to the specified
attribute of the embeddable instances contained in the collection). In these cases, the attributeName element must be specified.
To override conversion mappings at multiple levels of embedding, a dot (".") notation form must be
used in the attributeName element to indicate an attribute within an embedded attribute. The value
of each identifier used with the dot notation is the name of the respective embedded field or property.
When the Convert annotation is applied to a map containing instances of embeddable classes, the
attributeName element must be specified, and "key." or "value." must be used to prefix the
name of the attribute that is to be converted in order to specify it as part of the map key or map value.
When the Convert annotation is applied to a map to specify conversion of a map key of basic type,
"key" must be used as the value of the attributeName element to specify that it is the map key
that is to be converted.
The Convert annotation may be applied to an entity class that extends a mapped superclass to specify
or override a conversion mapping for an inherited basic or embedded attribute.
Example 1: Convert a basic attribute
@Converter
public class BooleanToIntegerConverter
implements AttributeConverter<Boolean, Integer> {
... }
@Entity
public class Employee {
@Id long id;
}
4/2/13
@Convert(converter=BooleanToIntegerConverter.class)
boolean fullTime;
...
436
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
Example 2: Auto-apply conversion of a basic attribute
@Converter(autoApply=true)
public class EmployeeDateConverter
implements AttributeConverter<com.acme.EmployeeDate, java.sql.Date> {
... }
@Entity
public class Employee {
@Id long id;
...
// EmployeeDateConverter is applied automatically
EmployeeDate startDate;
}
Example 3: Disable conversion in the presence of an auto-apply converter
@Convert(disableConversion=true)
EmployeeDate lastReview;
Example 4: Apply a converter to an element collection of basic type
@ElementCollection
// applies to each element in the collection
@Convert(converter=NameConverter.class)
List<String> names;
Example 5: Apply a converter to an element collection that is a map of basic values. The converter is
applied to the map value.
@ElementCollection
@Convert(converter=EmployeeNameConverter.class)
Map<String, String> responsibilities;
Example 6: Apply a converter to a map key of basic type
@OneToMany
@Convert(converter=ResponsibilityCodeConverter.class,
attributeName="key")
Map<String, Employee> responsibilities;
Example 7: Apply a converter to an embeddable attribute
@Embedded
@Convert(converter=CountryConverter.class,
attributeName="country")
Address address;
Example 8: Apply a converter to a nested embeddable attribute
@Embedded
@Convert(converter=CityConverter.class,
attributeName="region.city")
Address address;
JSR-338 Final Release
437
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
Example 9: Apply a converter to a nested attribute of an embeddable that is a map key of an element
collection
@Entity public class PropertyRecord {
...
@Convert(converter=CityConverter.class,
attributeName="key.region.city")
@ElementCollection
Map<Address, PropertyInfo> parcels;
}
Example 10: Apply a converter to an embeddable that is a map key for a relationship
@OneToMany
@Convert(converter=ResponsibilityCodeConverter.class,
attributeName="key.jobType")
Map<Responsibility, Employee> responsibilities;
Example 11: Override conversion mappings for attributes inherited from a mapped superclass
@Entity
@Converts({
@Convert(converter=DateConverter.class, attributeName="startDate"),
@Convert(converter=DateConverter.class, attributeName="endDate")})
public class FullTimeEmployee extends GenericEmployee { ... }
11.1.11 Converts Annotation
The Converts annotation is used to group Convert annotations. Multiple converters must not be
applied to the same basic attribute.
@Target({METHOD, FIELD, TYPE})
@Retention(RUNTIME)
public @interface Converts {
Convert[] value();
}
Table 14 lists the annotation elements that may be specified for the Converts annotation.
Table 14
4/2/13
Converts Annotation Elements
Type
Name
Description
Convert[]
value
(Required) The Convert mappings that are to be applied to
the entity or the field or property.
438
Default
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
Example: Multiple converters applied to an embedded attribute
@Embedded
@Converts({
@Convert(converter=CountryConverter.class,
attributeName="country"),
@Convert(converter=CityConverter.class,
attributeName="region.city")})
Address address;
11.1.12 DiscriminatorColumn Annotation
For the SINGLE_TABLE mapping strategy, and typically also for the JOINED strategy, the persistence
provider will use a type discriminator column. The DiscriminatorColumn annotation is used to
define the discriminator column for the SINGLE_TABLE and JOINED inheritance mapping strategies.
The strategy and the discriminator column are only specified in the root of an entity class hierarchy or
subhierarchy in which a different inheritance strategy is applied.[100]
The DiscriminatorColumn annotation can be specified on an entity class (including on an abstract
entity class).
If the DiscriminatorColumn annotation is missing, and a discriminator column is required, the
name of the discriminator column defaults to "DTYPE" and the discriminator type to STRING.
Table 15 lists the annotation elements that may be specified for the DiscriminatorColumn annotation and their default values.
The supported discriminator types are defined by the DiscriminatorType enum:
public enum DiscriminatorType { STRING, CHAR, INTEGER };
The type of the discriminator column, if specified in the optional columnDefinition element, must
be consistent with the discriminator type.
@Target({TYPE}) @Retention(RUNTIME)
public @interface DiscriminatorColumn {
String name() default "DTYPE";
DiscriminatorType discriminatorType() default STRING;
String columnDefinition() default "";
int length() default 31;
}
[100]The combination of inheritance strategies within a single entity inheritance hierarchy is not defined by this specification.
JSR-338 Final Release
439
4/2/13
Oracle
Metadata for Object/Relational Mapping
Table 15
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
DiscriminatorColumn Annotation Elements
Type
Name
Description
Default
String
name
(Optional) The name of column to be used
for the discriminator.
“DTYPE”
DiscriminatorType
discriminatorType
(Optional) The type of object/column to use
as a class discriminator.
DiscriminatorType.STRING
String
columnDefinition
(Optional) The SQL fragment that is used
when generating the DDL for the discriminator column.
Provider-generated SQL to
create a column of the specified discriminator type.
int
length
(Optional) The column length for
String-based discriminator types. Ignored
for other discriminator types.
31
Example:
@Entity
@Table(name="CUST")
@DiscriminatorColumn(name="DISC", discriminatorType=STRING,length=20)
public class Customer { ... }
@Entity
public class ValuedCustomer extends Customer { ... }
11.1.13 DiscriminatorValue Annotation
The DiscriminatorValue annotation is used to specify the value of the discriminator column for
entities of the given type. The DiscriminatorValue annotation can only be specified on a concrete
entity class. If the DiscriminatorValue annotation is not specified and a discriminator column is
used, a provider-specific function will be used to generate a value representing the entity type.
The inheritance strategy and the discriminator column are only specified in the root of an entity class
hierarchy or subhierarchy in which a different inheritance strategy is applied. The discriminator value, if
not defaulted, should be specified for each entity class in the hierarchy.
Table 16 lists the annotation elements that may be specified for the DiscriminatorValue annotation and their default values.
The discriminator value must be consistent in type with the discriminator type of the specified or
defaulted discriminator column. If the discriminator type is an integer, the value specified must be able
to be converted to an integer value (e.g., "1").
@Target({TYPE}) @Retention(RUNTIME)
public @interface DiscriminatorValue {
String value();
}
4/2/13
440
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Table 16
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
DiscriminatorValue Annotation Elements
Type
Name
Description
Default
String
value
(Optional) The value that indicates that
the row is an entity of the annotated entity
type.
If the DiscriminatorValue annotation is
not specified, a provider-specific function to generate a value representing
the entity type is used for the value of
the discriminator column. If the DiscriminatorType is STRING, the discriminator value default is the entity
name.
Example:
@Entity
@Table(name="CUST")
@Inheritance(strategy=SINGLE_TABLE)
@DiscriminatorColumn(name="DISC", discriminatorType=STRING,length=20)
@DiscriminatorValue("CUSTOMER")
public class Customer { ... }
@Entity
@DiscriminatorValue("VCUSTOMER")
public class ValuedCustomer extends Customer { ... }
11.1.14 ElementCollection Annotation
The ElementCollection annotation defines a collection of instances of a basic type or embeddable
class. The ElementCollection annotation (or equivalent XML element) must be specified if the
collection is to be mapped by means of a collection table.[101]
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface ElementCollection {
Class targetClass() default void.class;
FetchType fetch() default LAZY;
}
Table 17 lists the annotation elements that may be specified for the ElementCollection annotation
and their default values.
[101]If it is not specified, the rules of section 2.8 apply.
JSR-338 Final Release
441
4/2/13
Oracle
Metadata for Object/Relational Mapping
Table 17
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
ElementCollection Annotation Elements
Type
Name
Description
Default
Class
targetClass
(Optional) The basic or embeddable class that
is the element type of the collection. Optional
only if the collection field or property is
defined using Java generics. Must be specified
otherwise.
The parameterized type of the
collection when defined using
generics.
FetchType
fetch
(Optional) Whether the collection should be
lazily loaded or must be eagerly fetched. The
EAGER strategy is a requirement on the persistence provider runtime that the collection
elements must be eagerly fetched. The LAZY
strategy is a hint to the persistence provider
runtime.
LAZY
Example:
@Entity public class Person {
@Id protected String ssn;
protected String name;
}
@ElementCollection
protected Set<String> nickNames = new HashSet();
...
11.1.15 Embeddable Annotation
The Embeddable annotation is used to specify a class whose instances are stored as an intrinsic part
of an owning entity and share the identity of the entity.
@Documented @Target({TYPE}) @Retention(RUNTIME)
public @interface Embeddable {
}
Example 1:
@Embeddable
public class EmploymentPeriod {
@Temporal(DATE) java.util.Date startDate;
@Temporal(DATE) java.util.Date endDate;
...
}
4/2/13
442
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
Example 2:
@Embeddable public class PhoneNumber {
protected String areaCode;
protected String localNumber;
@ManyToOne PhoneServiceProvider provider;
...
}
@Entity public class PhoneServiceProvider {
@Id protected String name;
...
}
Example 3:
@Embeddable
protected
protected
protected
@Embedded
}
public class Address {
String street;
String city;
String state;
protected Zipcode zipcode;
@Embeddable public class Zipcode {
protected String zip;
protected String plusFour;
}
11.1.16 Embedded Annotation
The Embedded annotation is used to specify a persistent field or property of an entity or embeddable
class whose value is an instance of an embeddable class.[102] Each of the persistent properties or fields
of the embedded object is mapped to the database table for the entity or embeddable class. The
embeddable class must be annotated as Embeddable.[103]
The AttributeOverride, AttributeOverrides, AssociationOverride, and AssociationOverrides annotations may be used to override mappings declared or defaulted by the
embeddable class.
Implementations are not required to support embedded objects that are mapped across more than one
table (e.g., split across primary and secondary tables or multiple secondary tables).
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface Embedded {}
[102]If the embeddable class is used as a primary key, the EmbeddedId rather than the Embedded annotation is used.
[103]Use of the Embedded annotation is not required. See section 2.8.
JSR-338 Final Release
443
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
Example:
@Embedded
@AttributeOverrides({
@AttributeOverride(name="startDate",
[email protected](name="EMP_START")),
@AttributeOverride(name="endDate",
[email protected](name="EMP_END"))
})
public EmploymentPeriod getEmploymentPeriod() { ... }
11.1.17 EmbeddedId Annotation
The EmbeddedId annotation is applied to a persistent field or property of an entity class or mapped
superclass to denote a composite primary key that is an embeddable class. The embeddable class must
be annotated as Embeddable.[104] Relationship mappings defined within an embedded id class are not
supported.
There must be only one EmbeddedId annotation and no Id annotation when the EmbeddedId annotation is used.
The AttributeOverride annotation may be used to override the column mappings declared within
the embeddable class.
The MapsId annotation may be used in conjunction with the EmbeddedId annotation to specify a
derived primary key. See Sections 2.4.1 and 11.1.37.
If the entity has a derived primary key, the AttributeOverride annotation may only be used to
override those attributes of the embedded id that do not correspond to the relationship to the parent
entity.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface EmbeddedId {}
Example 1:
@Entity public class Employee {
}
@EmbeddedId protected EmployeePK empPK;
String name;
@ManyToOne Set<Department> dept;
...
[104]Note that theId annotation is not used in the embeddable class.
4/2/13
444
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
Example 2:
@Embeddable
public class DependentId {
String name;
EmployeeId empPK;
// corresponds to PK type of Employee
}
@Entity
public class Dependent {
// default column name for "name" attribute is overridden
@AttributeOverride(name="name", @Column(name="dep_name"))
@EmbeddedId DependentId id;
...
@MapsId("empPK")
@ManyToOne Employee emp;
}
11.1.18 Enumerated Annotation
An Enumerated annotation specifies that a persistent property or field should be persisted as a enumerated type. The Enumerated annotation may be used in conjunction with the Basic annotation.
The Enumerated annotation may be used in conjunction with the ElementCollection[105]
annotation when the element collection value is of basic type.
An enum can be mapped as either a string or an integer[106]. The EnumType enum defines the mapping
for enumerated types.
public enum EnumType {
ORDINAL,
STRING
}
If the enumerated type is not specified or the Enumerated annotation is not used, the enumerated type
is assumed to be ORDINAL unless a converter is being applied.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface Enumerated {
EnumType value() default ORDINAL;
}
Table 18 lists the annotation elements that may be specified for the Enumerated annotation and their
default values.
[105]If the element collection is a Map, this applies to the map value.
[106]Mapping of enum values that contain state is not supported.
JSR-338 Final Release
445
4/2/13
Oracle
Metadata for Object/Relational Mapping
Table 18
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
Enumerated Annotation Elements
Type
Name
Description
Default
EnumType
value
(Optional) The type used in mapping an enum type.
ORDINAL
Example:
public enum EmployeeStatus {FULL_TIME, PART_TIME, CONTRACT}
public enum SalaryRate {JUNIOR, SENIOR, MANAGER, EXECUTIVE}
@Entity public class Employee {
...
public EmployeeStatus getStatus() {...}
}
@Enumerated(STRING)
public SalaryRate getPayScale() {...}
...
If the status property is mapped to a column of integer type, and the payscale property to a column of
varchar type, an instance that has a status of PART_TIME and a pay rate of JUNIOR will be stored with
STATUS set to 1 and PAYSCALE set to "JUNIOR".
11.1.19 ForeignKey Annotation
The ForeignKey annotation is used to specify the handling of foreign key constraints when schema
generation is in effect. If this annotation is not specified, the persistence provider’s default foreign key
strategy will be used.
@Target({}) @Retention(RUNTIME)
public @interface ForeignKey {
String name() default "";
ConstraintMode value() default CONSTRAINT;
String foreignKeyDefinition() default "";
}
The name element specifies a name for the foreign key constraint.
The ConstraintMode enum is used to control the application of constraints.
public enum ConstraintMode {CONSTRAINT, NO_CONSTRAINT,
PROVIDER_DEFAULT}.
The enum values have the following semantics: A value of CONSTRAINT will cause the persistence
provider to generate a foreign key constraint. A value of NO_CONSTRAINT will result in no constraint
being generated. A value of PROVIDER_DEFAULT will result in the provider's default behavior (which
may or may not result in the generation of a constraint for any given join column or set of join columns).
4/2/13
446
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
The syntax used in the foreignKeyDefinition element should follow the SQL syntax used by the
target database for foreign key constraints. For example, this may be similar to the following:
FOREIGN KEY ( <COLUMN expression> {, <COLUMN expression>}... )
REFERENCES <TABLE identifier> [
( <COLUMN expression> {, <COLUMN expression>}... ) ]
[ ON UPDATE <referential action> ]
[ ON DELETE <referential action> ]
If the ForeignKey annotation is specified with a ConstraintMode value of CONSTRAINT, but
the foreignKeyDefinition element is not specified, the provider will generate a foreign key constraint whose update and delete actions it determines most appropriate for the join column(s) to which
the foreign key constraint is applied
Table 19 lists the annotation elements that may be specified for the ForeignKey annotation.
Table 19
ForeignKey Annotation Elements
Type
Name
Description
Default
String
name
(Optional) The name of the foreign key constraint.
A provider-generated
name.
ConstraintMode
value
(Optional) Whether to generate a constraint.
CONSTRAINT
String
foreignKeyDefinition
(Optional) The foreign key constraint definition.
Provider-default. If the
value of the ConstraintMode element is
NO_CONSTRAINT, the
provider must not generate a foreign key constraint.
11.1.20 GeneratedValue Annotation
The GeneratedValue annotation provides for the specification of generation strategies for the values of primary keys. The GeneratedValue annotation may be applied to a primary key property or
field of an entity or mapped superclass in conjunction with the Id annotation. [107] The use of the GeneratedValue annotation is only required to be supported for simple primary keys. Use of the GeneratedValue annotation is not supported for derived primary keys.
Table 20 lists the annotation elements that may be specified for the GeneratedValue annotation and
their default values.
The types of primary key generation are defined by the GenerationType enum:
public enum GenerationType { TABLE, SEQUENCE, IDENTITY, AUTO };
[107]Portable applications should not use the GeneratedValue annotation on other persistent fields or properties.
JSR-338 Final Release
447
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
The TABLE generator type value indicates that the persistence provider must assign primary keys for
the entity using an underlying database table to ensure uniqueness.
The SEQUENCE and IDENTITY values specify the use of a database sequence or identity column,
respectively.[108]
The further specification of table generators and sequence generators id described in sections 11.1.48
and 11.1.50.
The AUTO value indicates that the persistence provider should pick an appropriate strategy for the particular database. The AUTO generation strategy may expect a database resource to exist, or it may
attempt to create one. A vendor may provide documentation on how to create such resources in the
event that it does not support schema generation or cannot create the schema resource at runtime.
This specification does not define the exact behavior of these strategies.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface GeneratedValue {
GenerationType strategy() default AUTO;
String generator() default "";
}
Table 20
GeneratedValue Annotation Elements
Type
Name
Description
Default
GenerationType
strategy
(Optional) The primary key generation strategy that the persistence provider must use to
generate the annotated entity primary key.
GenerationType.AUTO
String
generator
(Optional) The name of the primary key generator to use as specified in the SequenceGenerator or TableGenerator annotation.
Default primary key generator
supplied by persistence provider.
Example 1:
@Id
@GeneratedValue(strategy=SEQUENCE, generator="CUST_SEQ")
@Column(name="CUST_ID")
public Long getId() { return id; }
Example 2:
@Id
@GeneratedValue(strategy=TABLE, generator="CUST_GEN")
@Column(name="CUST_ID")
Long id;
[108]Note that SEQUENCE and IDENTITY are not portable across all databases.
4/2/13
448
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
11.1.21 Id Annotation
The Id annotation specifies the primary key property or field of an entity. The Id annotation may be
applied in an entity or mapped superclass.
The field or property to which the Id annotation is applied should be one of the following types: any
Java primitive type; any primitive wrapper type; java.lang.String; java.util.Date;
java.sql.Date; java.math.BigDecimal; java.math.BigInteger[109]. See section 2.4.
The mapped column for the primary key of the entity is assumed to be the primary key of the primary
table. If no Column annotation is specified, the primary key column name is assumed to be the name of
the primary key property or field.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface Id {}
Example:
@Id
public Long getId() { return id; }
11.1.22 IdClass Annotation
The IdClass annotation is applied to an entity class or a mapped superclass to specify a composite
primary key class that is mapped to multiple fields or properties of the entity.
The names of the fields or properties in the primary key class and the primary key fields or properties of
the entity must correspond and their types must match according to the rules specified in Section 2.4,
“Primary Keys and Entity Identity” and Section 2.4.1, “Primary Keys Corresponding to Derived Identities”.
The Id annotation must also be applied to the corresponding fields or properties of the entity.
@Target({TYPE}) @Retention(RUNTIME)
public @interface IdClass {
Class value();
}
Table 21 lists the annotation elements that may be specified for the IdClass annotation.
Table 21
IdClass Annotation Elements
Type
Name
Description
Class
value
(Required) The composite primary key class.
Default
[109]Primary keys using types other than these will not be portable. In general, floating point types should never be used in primary
keys.
JSR-338 Final Release
449
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
Example:
@IdClass(com.acme.EmployeePK.class)
@Entity
public class Employee {
@Id String empName;
@Id Date birthDay;
...
}
11.1.23 Index Annotation
The Index annotation is used in schema generation. Note that it is not necessary to specify an index
for a primary key, as the primary key index will be created automatically, however, the Index annotation
may be used to specify the ordering of the columns in the index for the primary key.
@Target({}) @Retention(RUNTIME)
public @interface Index {
String name() default "";
String columnList();
boolean unique() default false;
}
The syntax of the columnList element is a column_list, as follows:
column::= index_column [,index_column]*
index_column::= column_name [ASC | DESC]
The persistence provider must observe the specified ordering of the columns.
If ASC or DESC is not specified, ASC (ascending order) is assumed.
Table 22 lists the annotation elements that may be specified for the Index annotation.
Table 22
Index Annotation Elements
Type
Name
Description
Default
String
name
(Optional) The name of the index.
A provider-generated name.
String
columnList
(Required) The names of the columns to be included in the
index.
boolean
unique
(Optional) Whether the index is unique.
false
11.1.24 Inheritance Annotation
The Inheritance annotation defines the inheritance strategy to be used for an entity class hierarchy.
It is specified on the entity class that is the root of the entity class hierarchy.
4/2/13
450
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
If the Inheritance annotation is not specified or if no inheritance type is specified for an entity class
hierarchy, the SINGLE_TABLE mapping strategy is used.
Support for the combination of inheritance strategies is not required by this specification. Portable
applications should only use a single inheritance strategy within an entity hierarchy.
The three inheritance mapping strategies are the single table per class hierarchy, joined subclass, and
table per concrete class strategies. See Section 2.12 for a more detailed discussion of inheritance strategies.
The inheritance strategy options are defined by the InheritanceType enum:
public enum InheritanceType
{ SINGLE_TABLE, JOINED, TABLE_PER_CLASS };
Support for the TABLE_PER_CLASS mapping strategy is optional in this release.
Table 23 lists the annotation elements that may be specified for the Inheritance annotation and
their default values.
@Target({TYPE}) @Retention(RUNTIME)
public @interface Inheritance {
InheritanceType strategy() default SINGLE_TABLE;
}
Table 23
Inheritance Annotation Elements
Type
Name
Description
Default
InheritanceType
strategy
(Optional) The inheritance strategy
to use for the entity inheritance hierarchy.
InheritanceType.SINGLE_TABLE
Example:
@Entity
@Inheritance(strategy=JOINED)
public class Customer { ... }
@Entity
public class ValuedCustomer extends Customer { ... }
11.1.25 JoinColumn Annotation
The JoinColumn annotation is used to specify a column for joining an entity association or element
collection.
Table 24 lists the annotation elements that may be specified for the JoinColumn annotation and their
default values.
JSR-338 Final Release
451
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
If the JoinColumn annotation itself is defaulted, a single join column is assumed and the default values described in Table 24 apply.
The name annotation element defines the name of the foreign key column. The remaining annotation
elements (other than referencedColumnName) refer to this column and have the same semantics as
for the Column annotation.
If the referencedColumnName element is missing, the foreign key is assumed to refer to the primary key of the referenced table.
Support for referenced columns that are not primary key columns of the referenced table is optional.
Applications that use such mappings will not be portable.
The foreignKey annotation element is used to specify or control the generation of a foreign key constraint when schema generation is in effect. If this element is not specified, the persistence provider’s
default foreign key strategy will apply.
If there is more than one join column, a JoinColumn annotation must be specified for each join column using the JoinColumns annotation. Both the name and the referencedColumnName elements must be specified in each such JoinColumn annotation.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface JoinColumn {
String name() default "";
String referencedColumnName() default "";
boolean unique() default false;
boolean nullable() default true;
boolean insertable() default true;
boolean updatable() default true;
String columnDefinition() default "";
String table() default "";
ForeignKey foreignKey() default @ForeignKey(PROVIDER_DEFAULT);
}
Table 24
4/2/13
JoinColumn Annotation Elements
Type
Name
Description
Default
String
name
(Optional) The name of the foreign key
column. The table in which it is found
depends upon the context. If the join is for
a OneToOne or ManyToOne mapping
using a foreign key mapping strategy, the
foreign key column is in the table of the
source entity or embeddable. If the join is
for a unidirectional OneToMany mapping
using a foreign key mapping strategy, the
foreign key is in the table of the target
entity. If the join is for a ManyToMany
mapping or for a OneToOne or bidirectional ManyToOne/OneToMany mapping
using a join table, the foreign key is in a
join table. If the join is for an element collection, the foreign key is in a collection
table.
(Default only applies if a single
join column is used.) The concatenation of the following: the name
of the referencing relationship
property or field of the referencing entity or embeddable class;
"_"; the name of the referenced
primary key column. If there is no
such referencing relationship
property or field in the entity, or if
the join is for an element collection, the join column name is
formed as the concatenation of the
following: the name of the entity;
"_"; the name of the referenced
primary key column.
452
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
Type
Name
Description
Default
String
referencedColumnName
(Optional) The name of the column referenced by this foreign key column. When
used with entity relationship mappings
other than the cases described below, the
referenced column is in the table of the target entity. When used with a unidirectional
OneToMany foreign key mapping, the referenced column is in the table of the
source entity. When used inside a JoinTable annotation, the referenced key column is in the entity table of the owning
entity, or inverse entity if the join is part of
the inverse join definition. When used in a
collection table mapping, the referenced
column is in the table of the entity containing the collection.
(Default only applies if single join
column is being used.) The same
name as the primary key column
of the referenced table.
boolean
unique
(Optional) Whether the property is a
unique key. This is a shortcut for the
UniqueConstraint annotation at the table
level and is useful for when the unique key
constraint is only a single field. It is not
necessary to explicitly specify this for a
join column that corresponds to a primary
key that is part of a foreign key.
false
boolean
nullable
(Optional) Whether the foreign key column is nullable.
true
boolean
insertable
(Optional) Whether the column is included
in SQL INSERT statements generated by
the persistence provider.
true
boolean
updatable
(Optional) Whether the column is included
in SQL UPDATE statements generated by
the persistence provider.
true
String
columnDefinition
(Optional) The SQL fragment that is used
when generating the DDL for the column.
Generated SQL for the column.
String
table
(Optional) The name of the table that contains the column.
If the join is for a OneToOne or
ManyToOne mapping using a foreign key mapping strategy, the
name of the table of the source
entity or embeddable. If the join is
for a unidirectional OneToMany
mapping using a foreign key mapping strategy, the name of the
table of the target entity. If the
join is for a ManyToMany mapping or for a OneToOne or bidirectional ManyToOne/
OneToMany mapping using a join
table, the name of the join table. If
the join is for an element collection, the name of the collection
table.
ForeignKey
foreignKey
(Optional) The foreign key constraint for
the join column. This is used only if table
generation is in effect.
Provider’s default
JSR-338 Final Release
453
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
Example 1:
@ManyToOne
@JoinColumn(name="ADDR_ID")
public Address getAddress() { return address; }
Example 2: Unidirectional One-to-Many association using a foreign key mapping.
In Customer class:
@OneToMany
@JoinColumn(name="CUST_ID") // join column is in table for Order
public Set<Order> getOrders() {return orders;}
11.1.26 JoinColumns Annotation
Composite foreign keys are supported by means of the JoinColumns annotation. The JoinColumns annotation groups JoinColumn annotations for the same relationship.
When the JoinColumns annotation is used, both the name and the referencedColumnName
elements must be specified in each of the grouped JoinColumn annotations.
The foreignKey annotation element is used to specify or control the generation of a foreign key constraint when schema generation is in effect. If both this element and the foreignKey element of any
of the JoinColumn elements referenced by the value element are specified, the behavior is undefined. If no foreignKey annotation element is specified in either location, the persistence provider's
default foreign key strategy will apply.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface JoinColumns {
JoinColumn[] value();
ForeignKey foreignKey() default @ForeignKey(PROVIDER_DEFAULT);
}
Table 25 lists the annotation elements that may be specified for the JoinColumns annotation.
Table 25
4/2/13
JoinColumns Annotation Elements
Type
Name
Description
JoinColumn[]
value
(Required) The join columns that map the relationship.
ForeignKey
foreignKey
(Optional) The foreign key constraint specification for the
join columns. This is used only if table generation is in
effect.
454
Default
Provider’s default
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
Example:
@ManyToOne
@JoinColumns({
@JoinColumn(name="ADDR_ID", referencedColumnName="ID"),
@JoinColumn(name="ADDR_ZIP", referencedColumnName="ZIP")
})
public Address getAddress() { return address; }
11.1.27 JoinTable Annotation
The JoinTable annotation is used in the mapping of entity associations. A JoinTable annotation
is specified on the owning side of the association. A join table is typically used in the mapping of
many-to-many and unidirectional one-to-many associations. It may also be used to map bidirectional
many-to-one/one-to-many associations, unidirectional many-to-one relationships, and one-to-one associations (both bidirectional and unidirectional).
Table 26 lists the annotation elements that may be specified for the JoinTable annotation and their
default values.
If the JoinTable annotation is not explicitly specified for the mapping of a many-to-many or unidirectional one-to-many relationship, the default values of the annotation elements apply.
The name of the join table is assumed to be the table names of the associated primary tables concatenated together (owning side first) using an underscore.
The foreignKey element is used to specify or control the generation of a foreign key constraint for
the columns corresponding to the joinColumns element when table generation is in effect. If both
this element and the foreignKey element of any of the joinColumns elements are specified, the
behavior is undefined. If no foreignKey annotation element is specified in either location, the persistence provider's default foreign key strategy will apply. The inverseForeignKey element applies
to the generation of a foreign key constraint for the columns corresponding to the inverseJoinColumns element, and similar rules apply.
When a join table is used in mapping a relationship with an embeddable class on the owning side of the
relationship, the containing entity rather than the embeddable class is considered the owner of the relationship.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface JoinTable {
String name() default "";
String catalog() default "";
String schema() default "";
JoinColumn[] joinColumns() default {};
JoinColumn[] inverseJoinColumns() default {};
ForeignKey foreignKey() default @ForeignKey(PROVIDER_DEFAULT);
ForeignKey inverseForeignKey()
default @ForeignKey(PROVIDER_DEFAULT);
UniqueConstraint[] uniqueConstraints() default {};
Index[] indexes() default {};
}
JSR-338 Final Release
455
4/2/13
Oracle
Metadata for Object/Relational Mapping
Table 26
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
JoinTable Annotation Elements
Type
Name
Description
Default
String
name
(Optional) The name of the join table.
The concatenated names of
the two associated primary
entity tables (owning side
first), separated by an underscore.
String
catalog
(Optional) The catalog of the table.
Default catalog.
String
schema
(Optional) The schema of the table.
Default schema for user.
JoinColumn[]
joinColumns
(Optional) The foreign key columns
of the join table which reference the
primary table of the entity owning the
association (i.e. the owning side of
the association).
The same defaults as for
JoinColumn.
JoinColumn[]
inverseJoinColumns
(Optional) The foreign key columns
of the join table which reference the
primary table of the entity that does
not own the association (i.e. the
inverse side of the association).
The same defaults as for
JoinColumn.
ForeignKey
foreignKey
(Optional) The foreign key constraint specification for the join columns. This is used only if table
generation is in effect.
Provider’s default.
ForeignKey
inverseForeignKey
(Optional) The foreign key constraint specification for the inverse
join columns. This is used only if
table generation is in effect.
Provider’s default.
UniqueConstraint[]
uniqueConstraints
(Optional) Unique constraints that are
to be placed on the table. These are
only used if table generation is in
effect.
No additional constraints
Index[]
indexes
(Optional) Indexes for the table.
These are only used if table generation is in effect.
No additional indexes
Example:
@JoinTable(
name="CUST_PHONE",
joinColumns=
@JoinColumn(name="CUST_ID", referencedColumnName="ID"),
inverseJoinColumns=
@JoinColumn(name="PHONE_ID", referencedColumnName="ID")
)
4/2/13
456
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
11.1.28 Lob Annotation
A Lob annotation specifies that a persistent property or field should be persisted as a large object to a
database-supported large object type. Portable applications should use the Lob annotation when mapping to a database Lob type. The Lob annotation may be used in conjunction with the Basic annotation or with the ElementCollection[110] annotation when the element collection value is of basic
type. A Lob may be either a binary or character type. The Lob type is inferred from the type of the persistent field or property and, except for string and character types, defaults to Blob.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface Lob {
}
Example 1:
@Lob @Basic(fetch=EAGER)
@Column(name="REPORT")
protected String report;
Example 2:
@Lob @Basic(fetch=LAZY)
@Column(name="EMP_PIC", columnDefinition="BLOB NOT NULL")
protected byte[] pic;
11.1.29 ManyToMany Annotation
A ManyToMany annotation defines a many-valued association with many-to-many multiplicity. If the
collection is defined using generics to specify the element type, the associated target entity class does
not need to be specified; otherwise it must be specified.
Every many-to-many association has two sides, the owning side and the non-owning, or inverse, side. If
the association is bidirectional, either side may be designated as the owning side. If the relationship is
bidirectional, the non-owning side must use the mappedBy element of the ManyToMany annotation to
specify the relationship field or property of the owning side.
The join table for the relationship, if not defaulted, is specified on the owning side.
The ManyToMany annotation may be used within an embeddable class contained within an entity class
to specify a relationship to a collection of entities[111]. If the relationship is bidirectional and the entity
containing the embeddable class is the owner of the relationship, the non-owning side must use the
mappedBy element of the ManyToMany annotation to specify the relationship field or property of the
embeddable class. The dot (".") notation syntax must be used in the mappedBy element to indicate
the relationship attribute within the embedded attribute. The value of each identifier used with the dot
notation is the name of the respective embedded field or property.
[110] If the element collection is a Map, this applies to the map value.
[111] The ManyToMany annotation must not be used within an embeddable class used in an element collection.
JSR-338 Final Release
457
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
Table 27 lists these annotation elements that may be specified for the ManyToMany annotation and
their default values.
The cascade element specifies the set of cascadable operations that are propagated to the associated
entity. The operations that are cascadable are defined by the CascadeType enum:
public enum CascadeType { ALL, PERSIST, MERGE, REMOVE, REFRESH, DETACH};
The value cascade=ALL is equivalent to cascade={PERSIST, MERGE, REMOVE, REFRESH,
DETACH}.
When the collection is a java.util.Map, the cascade element applies to the map value.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface ManyToMany {
Class targetEntity() default void.class;
CascadeType[] cascade() default {};
FetchType fetch() default LAZY;
String mappedBy() default "";
}
The EAGER strategy is a requirement on the persistence provider runtime that the associated entity must
be eagerly fetched. The LAZY strategy is a hint to the persistence provider runtime that the associated
entity should be fetched lazily when it is first accessed. The implementation is permitted to eagerly
fetch associations for which the LAZY strategy hint has been specified.
Table 27
4/2/13
ManyToMany Annotation Elements
Type
Name
Description
Default
Class
targetEntity
(Optional) The entity class that is the target
of the association. Optional only if the collection-valued relationship property is
defined using Java generics. Must be specified otherwise.
The parameterized type of
the collection when defined
using generics.
CascadeType[]
cascade
(Optional) The operations that must be cascaded to the target of the association.
No operations are cascaded.
FetchType
fetch
(Optional) Whether the association should be
lazily loaded or must be eagerly fetched. The
EAGER strategy is a requirement on the persistence provider runtime that the associated
entities must be eagerly fetched. The LAZY
strategy is a hint to the persistence provider
runtime.
LAZY
String
mappedBy
The field or property that owns the relationship. Required unless the relationship is unidirectional.
458
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
Example 1:
In Customer class:
@ManyToMany
@JoinTable(name="CUST_PHONES")
public Set<PhoneNumber> getPhones() { return phones; }
In PhoneNumber class:
@ManyToMany(mappedBy="phones")
public Set<Customer> getCustomers() { return customers; }
Example 2:
In Customer class:
@ManyToMany(targetEntity=com.acme.PhoneNumber.class)
public Set getPhones() { return phones; }
In PhoneNumber class:
@ManyToMany(targetEntity=com.acme.Customer.class, mappedBy="phones")
public Set getCustomers() { return customers; }
Example 3:
In Customer class:
@ManyToMany
@JoinTable(
name="CUST_PHONE",
joinColumns=
@JoinColumn(name="CUST_ID", referencedColumnName="ID"),
inverseJoinColumns=
@JoinColumn(name="PHONE_ID", referencedColumnName="ID")
)
public Set<PhoneNumber> getPhones() { return phones; }
In PhoneNumberClass:
@ManyToMany(mappedBy="phones")
public Set<Customer> getCustomers() { return customers; }
Example 4:
Embeddable class used by the Employee entity specifies a many-to-many relationship.
@Entity
public class Employee {
@Id int id;
@Embedded ContactInfo contactInfo;
...
}
JSR-338 Final Release
459
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
@Embeddable
public class ContactInfo {
@ManyToOne Address address; // Unidirectional
@ManyToMany List<PhoneNumber> phoneNumbers; // Bidirectional
}
@Entity
public class PhoneNumber {
@Id int phNumber;
@ManyToMany(mappedBy="contactInfo.phoneNumbers")
Collection<Employee> employees;
}
11.1.30 ManyToOne Annotation
The ManyToOne annotation defines a single-valued association to another entity class that has
many-to-one multiplicity. It is not normally necessary to specify the target entity explicitly since it can
usually be inferred from the type of the object being referenced.
The ManyToOne annotation may be used within an embeddable class to specify a relationship from the
embeddable class to an entity class. If the relationship is bidirectional, the non-owning OneToMany
entity side must use the mappedBy element of the OneToMany annotation to specify the relationship
field or property of the embeddable field or property on the owning side of the relationship. The dot
(".") notation syntax must be used in the mappedBy element to indicate the relationship attribute
within the embedded attribute. The value of each identifier used with the dot notation is the name of the
respective embedded field or property.
Table 28 lists the annotation elements that may be specified for the ManyToOne annotation and their
default values.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface ManyToOne {
Class targetEntity() default void.class;
CascadeType[] cascade() default {};
FetchType fetch() default EAGER;
boolean optional() default true;
}
The operations that can be cascaded are defined by the CascadeType enum, defined in section
11.1.29.
The EAGER strategy is a requirement on the persistence provider runtime that the associated entity must
be eagerly fetched. The LAZY strategy is a hint to the persistence provider runtime that the associated
entity should be fetched lazily when it is first accessed. The implementation is permitted to eagerly
fetch associations for which the LAZY strategy hint has been specified.
4/2/13
460
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Table 28
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
ManyToOne Annotation Elements
Type
Name
Description
Default
Class
targetEntity
(Optional) The entity class that is the target of
the association.
The type of the field or
property that stores the
association.
CascadeType[]
cascade
(Optional) The operations that must be cascaded to the target of the association.
No operations are cascaded.
FetchType
fetch
(Optional) Whether the association should be
lazily loaded or must be eagerly fetched. The
EAGER strategy is a requirement on the persistence provider runtime that the associated entity
must be eagerly fetched. The LAZY strategy is
a hint to the persistence provider runtime.
EAGER
boolean
optional
(Optional) Whether the association is optional.
If set to false then a non-null relationship must
always exist.
true
Example 1:
@ManyToOne(optional=false)
@JoinColumn(name="CUST_ID", nullable=false, updatable=false)
public Customer getCustomer() { return customer; }
Example 2:
@Entity
public class Employee {
@Id int id;
@Embedded JobInfo jobInfo;
...
}
@Embeddable
public class JobInfo {
String jobDescription;
@ManyToOne ProgramManager pm; // Bidirectional
}
@Entity
public class ProgramManager {
@Id int id;
@OneToMany(mappedBy="jobInfo.pm")
Collection<Employee> manages;
}
JSR-338 Final Release
461
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
11.1.31 MapKey Annotation
The MapKey annotation is used to specify the map key for associations of type java.util.Map
when the map key is itself the primary key or a persistent field or property of the entity that is the value
of the map.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface MapKey {
String name() default "";
}
The name element designates the name of the persistent field or property of the associated entity that is
used as the map key. If the name element is not specified, the primary key of the associated entity is
used as the map key. If the primary key is a composite primary key and is mapped as IdClass, an
instance of the primary key class is used as the key.
If a persistent field or property other than the primary key is used as a map key, it is expected to be
unique within the context of the relationship.
The MapKeyClass annotation is not used when MapKey is specified and vice versa.
Table 29 lists the annotation elements that may be specified for the MapKey annotation.
Table 29
MapKey Annotation Elements
Type
Name
Description
Default
String
name
(Optional) The name of the persistent field or property
that is used as the map key.
The primary key is
used as the map
key.
Example 1:
@Entity
public class Department {
...
@OneToMany(mappedBy="department")
@MapKey // map key is primary key
public Map<Integer, Employee> getEmployees() {... }
...
}
@Entity
public class Employee {
...
@Id public Integer getEmpId() { ... }
}
4/2/13
@ManyToOne
@JoinColumn(name="dept_id")
public Department getDepartment() { ... }
...
462
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
Example 2:
@Entity
public class Department {
...
@OneToMany(mappedBy="department")
@MapKey(name="name")
public Map<String, Employee> getEmployees() {... }
...
}
@Entity
public class Employee {
@Id public Integer getEmpId() { ... }
...
public String getName() { ... }
...
@ManyToOne
@JoinColumn(name="dept_id")
public Department getDepartment() { ... }
...
}
11.1.32 MapKeyClass Annotation
The MapKeyClass annotation is used to specify the type of the map key for associations of type
java.util.Map. The map key can be a basic type, an embeddable class, or an entity. If the map is
specified using Java generics, the MapKeyClass annotation and associated type need not be specified;
otherwise they must be specified.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface MapKeyClass {
Class value();
}
The MapKeyClass annotation is used in conjunction with ElementCollection or one of the collection-valued relationship annotations (OneToMany or ManyToMany).
The MapKey annotation is not used when MapKeyClass is specified and vice versa.
Table 30 lists the annotation elements that may be specified for the MapKeyClass annotation.
Table 30
MapKeyClass Annotation Elements
Type
Name
Description
Class
value
(Required) The type of the map key.
JSR-338 Final Release
463
Default
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
Example 1:
@Entity
public class Item {
@Id int id;
...
@ElementCollection(targetClass=String.class)
@MapKeyClass(String.class)
Map images; // map from image name to image filename
...
}
Example 2:
// MapKeyClass and target type of relationship can be defaulted
@Entity
public class Item {
@Id int id;
...
@ElementCollection
Map<String, String> images;
...
}
Example 3:
@Entity
public class Company {
@Id int id;
...
@OneToMany(targetEntity=com.example.VicePresident.class)
@MapKeyClass(com.example.Division.class)
Map organization;
}
Example 4:
// MapKeyClass and target type of relationship are defaulted
@Entity
public class Company {
@Id int id;
...
@OneToMany
Map<Division, VicePresident> organization;
}
4/2/13
464
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
11.1.33 MapKeyColumn Annotation
The MapKeyColumn annotation is used to specify the mapping for the key column of a map whose
map key is a basic type. If the name element is not specified, it defaults to the concatenation of the following: the name of the referencing relationship field or property; "_"; "KEY".
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface MapKeyColumn {
String name() default "";
boolean unique() default false;
boolean nullable() default false;
boolean insertable() default true;
boolean updatable() default true;
String columnDefinition() default "";
String table() default "";
int length() default 255;
int precision() default 0; // decimal precision
int scale() default 0; // decimal scale
}
If no MapKeyColumn annotation is specified, the default values in Table 31 apply.
Table 31
MapKeyColumn Annotation Elements
Type
Name
Description
Default
String
name
(Optional) The name of the map key column. The table in which it is found
depends upon the context. If the map
key is for an element collection, the map
key column is in the collection table for
the map value. If the map key is for a
ManyToMany entity relationship or for a
OneToMany entity relationship using a
join table, the map key column is in a
join table. If the map key is for a OneToMany entity relationship using a foreign
key mapping strategy, the map key column is in the table of the entity that is
the value of the map.
The concatenation of the following: the name of the referencing
property or field name; "_";
"KEY".
boolean
unique
(Optional) Whether the column is a
unique key. This is a shortcut for the
UniqueConstraint annotation at the table
level and is useful for when the unique
key constraint corresponds to only a single column. This constraint applies in
addition to any constraint entailed by
primary key mapping and to constraints
specified at the table level.
false
boolean
nullable
(Optional) Whether the database column
is nullable.
true
boolean
insertable
(Optional) Whether the column is
included in SQL INSERT statements
generated by the persistence provider.
true
JSR-338 Final Release
465
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
Type
Name
Description
Default
boolean
updatable
(Optional) Whether the column is
included in SQL UPDATE statements
generated by the persistence provider.
true
String
columnDefinition
(Optional) The SQL fragment that is
used when generating the DDL for the
column.
Generated SQL to create a column
of the inferred type.
String
table
(Optional) The name of the table that
contains the column.
If the map key is for an element
collection, the name of the collection table for the map value. If the
map key is for a OneToMany or
ManyToMany entity relationship
using a join table, the name of the
join table for the map. If the map
key is for a OneToMany entity
relationship using a foreign key
mapping strategy, the name of the
primary table of the entity that is
the value of the map.
int
length
(Optional) The column length. (Applies
only if a string-valued column is used.)
255
int
precision
(Optional) The precision for a decimal
(exact numeric) column. (Applies only if
a decimal column is used.)
0 (Value must be set by developer.)
int
scale
(Optional) The scale for a decimal (exact
numeric) column. (Applies only if a decimal column is used.)
0
Example:
@Entity
public class Item {
@Id int id;
...
@ElementCollection
@MapKeyColumn(name="IMAGE_NAME")
@Column(name="IMAGE_FILENAME")
@CollectionTable(name="IMAGE_MAPPING")
Map<String, String> images; // map from image name to filename
...
}
11.1.34 MapKeyEnumerated Annotation
The MapKeyEnumerated annotation is used to specify the enum type for a map key whose basic type
is an enumerated type.
The MapKeyEnumerated annotation can be applied to an element collection or relationship of type
java.util.Map, in conjunction with the ElementCollection, OneToMany, or ManyToMany
annotation. If the map is specified using Java generics, the MapKeyClass annotation and associated
type need not be specified; otherwise they must be specified.
4/2/13
466
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
If the enumerated type is not specified or the MapKeyEnumerated annotation is not used, the enumerated type is assumed to be ORDINAL.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface MapKeyEnumerated {
EnumType value() default ORDINAL;
}
Table 32 lists the annotation elements that may be specified for the MapKeyEnumerated annotation
and their default values. The EnumType enum is defined in section 11.1.18.
Table 32
MapKeyEnumerated Annotation Elements
Type
Name
Description
Default
EnumType
value
(Optional) The type used in mapping an enum type.
ORDINAL
11.1.35 MapKeyJoinColumn Annotation
The MapKeyJoinColumn annotation is used to specify a mapping to an entity that is a map key. The
map key join column is in the collection table, join table, or table of the target entity that is used to represent the map.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface MapKeyJoinColumn {
String name() default "";
String referencedColumnName() default "";
boolean unique() default false;
boolean nullable() default false;
boolean insertable() default true;
boolean updatable() default true;
String columnDefinition() default "";
String table() default "";
ForeignKey foreignKey() default @ForeignKey(PROVIDER_DEFAULT);
}
Table 33 lists the annotation elements that may be specified for the MapKeyJoinColumn annotation
and their default values.
If no MapKeyJoinColumn annotation is specified, a single join column is assumed and the default
values described below (and in Table 33) apply.
The name annotation element defines the name of the foreign key column. The remaining annotation
elements (other than referencedColumnName) refer to this column.
If there is a single map key join column, and if the name annotation member is missing, the map key
join column name is formed as the concatenation of the following: the name of the referencing relationship property or field of the referencing entity or embeddable; "_"; "KEY".
JSR-338 Final Release
467
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
If the referencedColumnName element is missing, the foreign key is assumed to refer to the primary key of the referenced table. Support for referenced columns that are not primary key columns of
the referenced table is optional. Applications that use such mappings will not be portable.
The foreignKey element is used to specify or control the generation of a foreign key constraint for
the map key join column when table generation is in effect. If the foreignKey element is not specified, the persistence provider’s default foreign key strategy will be used.
If there is more than one map key join column, a MapKeyJoinColumn annotation must be specified
for each join column using the MapKeyJoinColumns annotation. Both the name and the referencedColumnName elements must be specified in each such MapKeyJoinColumn annotation.
Table 33
4/2/13
MapKeyJoinColumn Annotation Elements
Type
Name
Description
Default
String
name
(Optional) The name of the foreign key
column for the map key. The table in
which it is found depends upon the context. If the join is for a map key for an
element collection, the foreign key column is in the collection table for the map
value. If the join is for a map key for a
ManyToMany entity relationship or for a
OneToMany entity relationship using a
join table, the foreign key column is in a
join table. If the join is for a OneToMany
entity relationship using a foreign key
mapping strategy, the foreign key column for the map key is in the table of the
entity that is the value of the map.
(Default only applies if a
single join column is used.)
The concatenation of the
following: the name of the
referencing relationship
property or field of the referencing entity or
embeddable class; "_";
"KEY".
String
referencedColumnName
(Optional) The name of the column referenced by this foreign key column. The
referenced column is in the table of the
target entity.
(Default only applies if single join column is being
used.) The same name as
the primary key column of
the referenced table.
boolean
unique
(Optional) Whether the property is a
unique key. This is a shortcut for the
UniqueConstraint annotation at the table
level and is useful for when the unique
key constraint is only a single field.
false
boolean
nullable
(Optional) Whether the foreign key column is nullable.
true
boolean
insertable
(Optional) Whether the column is
included in SQL INSERT statements
generated by the persistence provider.
true
boolean
updatable
(Optional) Whether the column is
included in SQL UPDATE statements
generated by the persistence provider.
true
String
columnDefinition
(Optional) The SQL fragment that is
used when generating the DDL for the
column.
Generated SQL for the column.
468
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
Type
Name
Description
Default
String
table
(Optional) The name of the table that
contains the foreign key column. If the
join is for a map key for an element collection, the foreign key column is in the
collection table for the map value. If the
join is for a map key for a ManyToMany
entity relationship or for a OneToMany
entity relationship using a join table, the
foreign key column is in a join table. If
the join is for a OneToMany entity relationship using a foreign key mapping
strategy, the foreign key column for the
map key is in the table of the entity that
is the value of the map.
If the map is for an element
collection, the name of the
collection table for the map
value. If the map is for a
OneToMany or ManyToMany entity relationship
using a join table, the name
of the join table for the map.
If the map is for a OneToMany entity relationship
using a foreign key mapping strategy, the name of
the primary table of the
entity that is the value of the
map.
ForeignKey
foreignKey
(Optional) The foreign key constraint
specification for the join column. This is
used only if table generation is in effect.
Provider’s default
Example 1:
@Entity
public class Company {
@Id int id;
...
@OneToMany
// unidirectional
@JoinTable(
name="COMPANY_ORGANIZATION",
[email protected](name="COMPANY"),
[email protected](name="VICEPRESIDENT"))
@MapKeyJoinColumn(name="DIVISION")
Map<Division, VicePresident> organization;
}
Example 2:
@Entity
public class VideoStore {
@Id int id;
String name;
Address location;
...
@ElementCollection
@CollectionTable(name="INVENTORY",
[email protected](name="STORE"))
@Column(name="COPIES_IN_STOCK")
@MapKeyJoinColumn(name="MOVIE", referencedColumnName="ID")
Map<Movie, Integer> videoInventory;
...
}
JSR-338 Final Release
469
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
@Entity
public class Movie {
@Id long id;
String title;
...
}
Example 3:
@Entity
public class Student {
@Id int studentId;
...
@ManyToMany // students and courses are also many-many
@JoinTable(name="ENROLLMENTS",
[email protected](name="STUDENT"),
[email protected](name="SEMESTER"))
@MapKeyJoinColumn(name="COURSE")
Map<Course, Semester> enrollment;
...
}
11.1.36 MapKeyJoinColumns Annotation
Composite map keys referencing entities are supported by means of the MapKeyJoinColumns annotation. The MapKeyJoinColumns annotation groups MapKeyJoinColumn annotations.
When the MapKeyJoinColumns annotation is used, both the name and the referencedColumnName elements must be specified in each of the grouped MapKeyJoinColumn annotations.
The foreignKey element is used to specify or control the generation of a foreign key constraint for
the columns corresponding to the MapKeyJoinColumn elements referenced by the value element
when table generation is in effect. If both this element and the foreignKey element of any of the
MapKeyJoinColumn elements are specified, the behavior is undefined. If no foreignKey annotation element is specified in either location, the persistence provider's default foreign key strategy will
apply.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface MapKeyJoinColumns {
MapKeyJoinColumn[] value();
ForeignKey foreignKey() default @ForeignKey(PROVIDER_DEFAULT);
}
Table 34 lists the annotation elements that may be specified for the MapKeyJoinColumns annotation.
4/2/13
470
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Table 34
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
MapKeyJoinColumns Annotation Elements
Type
Name
Description
Default
MapKeyJoinColumn[]
value
(Required) The map key join columns that are used to map
to the entity that is the map key.
ForeignKey
foreignKey
(Optional) The foreign key constraint specification for the
join columns. This is used only if table generation is in
effect.
Provider’s default
11.1.37 MapKeyTemporal Annotation
The MapKeyTemporal annotation is used to specify the temporal type for a map key whose basic
type is a temporal type.
The MapKeyTemporal annotation can be applied to an element collection or relationship of type
java.util.Map, in conjunction with the ElementCollection, OneToMany, or ManyToMany
annotation. If the map is specified using Java generics, the MapKeyClass annotation and associated
type need not be specified; otherwise they must be specified.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface MapKeyTemporal {
TemporalType value();
}
Table 35 lists the annotation elements that may be specified for the MapKeyTemporal annotation and
their default values. The TemporalType enum is defined in section 11.1.51.
Table 35
MapKeyTemporal Annotation Elements
Type
Name
Description
TemporalType
value
(Required) The type used in mapping
java.util.Date or java.util.Calendar.
Default
11.1.38 MappedSuperclass Annotation
The MappedSuperclass annotation designates a class whose mapping information is applied to the
entities that inherit from it. A mapped superclass has no separate table defined for it.
JSR-338 Final Release
471
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
A class designated with the MappedSuperclass annotation can be mapped in the same way as an
entity except that the mappings will apply only to its subclasses since no table exists for the mapped
superclass itself. When applied to the subclasses the inherited mappings will apply in the context of the
subclass tables. Mapping information may be overridden in such subclasses by using the AttributeOverride, AttributeOverrides, AssociationOverride, and AssociationOverrides annotations.
@Documented @Target(TYPE) @Retention(RUNTIME)
public @interface MappedSuperclass {}
11.1.39 MapsId Annotation
The MapsId annotation is used to designate a ManyToOne or OneToOne relationship attribute that
provides the mapping for an EmbeddedId primary key, an attribute within an EmbeddedId primary
key, or a simple primary key of the parent entity.
The value element specifies the attribute within a composite key to which the relationship attribute
corresponds. If the entity’s primary key is of the same Java type as the primary key of the entity referenced by the relationship, the value attribute is not specified.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface MapsId {
String value() default "";
}
Table 36 lists the annotation elements that may be specified for the MapsId annotation.
Table 36
MapsId Annotation Elements
Type
Name
Description
Default
String
value
(Optional) The name of the attribute within the composite
key to which the relationship attribute corresponds.
The relationship
maps the entity’s
primary key.
Example:
// parent entity has simple primary key
@Entity
public class Employee {
@Id long empId;
String name;
...
}
4/2/13
472
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
// dependent entity uses EmbeddedId for composite key
@Embeddable
public class DependentId {
String name;
long empid;
// corresponds to PK type of Employee
}
@Entity
public class Dependent {
@EmbeddedId DependentId id;
...
@MapsId("empid") // maps the empid attribute of embedded id
@ManyToOne Employee emp;
}
11.1.40 OneToMany Annotation
A OneToMany annotation defines a many-valued association with one-to-many multiplicity.
Table 37 lists the annotation elements that may be specified for the OneToMany annotation and their
default values.
If the collection is defined using generics to specify the element type, the associated target entity class
need not be specified; otherwise it must be specified.
The OneToMany annotation may be used within an embeddable class contained within an entity class
to specify a relationship to a collection of entities[112]. If the relationship is bidirectional, the
mappedBy element must be used to specify the relationship field or property of the entity that is the
owner of the relationship.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface OneToMany {
Class targetEntity() default void.class;
CascadeType[] cascade() default {};
FetchType fetch() default LAZY;
String mappedBy() default "";
boolean orphanRemoval() default false;
}
The operations that can be cascaded are defined by the CascadeType enum, defined in section
11.1.29.
When the collection is a java.util.Map, the cascade element and the orphanRemoval element apply to the map value.
If orphanRemoval is true and an entity that is the target of the relationship is removed from the
relationship (either by removal from the collection or by setting the relationship to null), the remove
operation will be applied to the entity being orphaned. If the entity being orphaned is a detached, new,
or removed entity, the semantics of orphanRemoval do not apply.
[112] The OneToMany annotation must not be used within an embeddable class used in an element collection.
JSR-338 Final Release
473
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
If orphanRemoval is true and the remove operation is applied to the source entity, the remove
operation will be cascaded to the relationship target in accordance with the rules of section 3.2.3, (and
hence it is not necessary to specify cascade=REMOVE for the relationship)[113].
The remove operation is applied at the time of the flush operation. The orphanRemoval functionality
is intended for entities that are privately "owned" by their parent entity. Portable applications must otherwise not depend upon a specific order of removal, and must not reassign an entity that has been
orphaned to another relationship or otherwise attempt to persist it.
The default mapping for unidirectional one-to-many relationships uses a join table as is described in
Section 2.10.5. Unidirectional one-to-many relationships may be implemented using one-to-many foreign key mappings, using the JoinColumn and JoinColumns annotations.
Table 37
OneToMany Annotation Elements
Type
Name
Description
Default
Class
targetEntity
(Optional) The entity class that is the target
of the association. Optional only if the collection-valued relationship property is
defined using Java generics. Must be specified otherwise.
The parameterized type of
the collection when defined
using generics.
CascadeType[]
cascade
(Optional) The operations that must be cascaded to the target of the association.
No operations are cascaded.
FetchType
fetch
(Optional) Whether the association should be
lazily loaded or must be eagerly fetched. The
EAGER strategy is a requirement on the persistence provider runtime that the associated
entities must be eagerly fetched. The LAZY
strategy is a hint to the persistence provider
runtime.
LAZY
String
mappedBy
The field or property that owns the relationship. Required unless the relationship is unidirectional.
boolean
orphanRemoval
(Optional) Whether to apply the remove
operation to entities that have been removed
from the relationship and to cascade the
remove operation to those entities.
false
Example 1: One-to-Many association using generics
In Customer class:
@OneToMany(cascade=ALL, mappedBy="customer", orphanRemoval=true)
public Set<Order> getOrders() { return orders; }
[113] If the parent is detached or new or was previously removed before the orphan was associated with it, the remove operation is not
applied to the entity being orphaned.
4/2/13
474
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
In Order class:
@ManyToOne
@JoinColumn(name="CUST_ID", nullable=false)
public Customer getCustomer() { return customer; }
Example 2: One-to-Many association without using generics
In Customer class:
@OneToMany(
targetEntity=com.acme.Order.class,
cascade=ALL,
mappedBy="customer",
orphanRemoval=true
)
public Set getOrders() { return orders; }
In Order class:
@ManyToOne
@JoinColumn(name="CUST_ID", nullable=false)
protected Customer customer;
Example 3: Unidirectional One-to-Many association using a foreign key mapping
In Customer class:
@OneToMany(orphanRemoval=true)
@JoinColumn(name="CUST_ID") // join column is in table for Order
public Set<Order> getOrders() {return orders;}
11.1.41 OneToOne Annotation
The OneToOne annotation defines a single-valued association to another entity that has one-to-one
multiplicity. It is not normally necessary to specify the associated target entity explicitly since it can
usually be inferred from the type of the object being referenced.
If the relationship is bidirectional, the mappedBy element must be used to specify the relationship field
or property of the entity that is the owner of the relationship.
The OneToOne annotation may be used within an embeddable class to specify a relationship from the
embeddable class to an entity class. If the relationship is bidirectional and the entity containing the
embeddable class is on the owning side of the relationship, the non-owning side must use the
mappedBy element of the OneToOne annotation to specify the relationship field or property of the
embeddable class. The dot (".") notation syntax must be used in the mappedBy element to indicate
the relationship attribute within the embedded attribute. The value of each identifier used with the dot
notation is the name of the respective embedded field or property.
Table 38 lists the annotation elements that may be specified for the OneToOne annotation and their
default values.
JSR-338 Final Release
475
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface OneToOne {
Class targetEntity() default void.class;
CascadeType[] cascade() default {};
FetchType fetch() default EAGER;
boolean optional() default true;
String mappedBy() default "";
boolean orphanRemoval() default false;
}
The operations that can be cascaded are defined by the CascadeType enum, defined in section
11.1.29.
If orphanRemoval is true and an entity that is the target of the relationship is removed from the
relationship (by setting the relationship to null), the remove operation will be applied to the entity being
orphaned. If the entity being orphaned is a detached, new, or removed entity, the semantics of
orphanRemoval do not apply.
If orphanRemoval is true and the remove operation is applied to the source entity, the remove
operation will be cascaded to the relationship target in accordance with the rules of section 3.2.3, (and
hence it is not necessary to specify cascade=REMOVE for the relationship)[114].
The remove operation is applied at the time of the flush operation. The orphanRemoval functionality
is intended for entities that are privately "owned" by their parent entity. Portable applications must otherwise not depend upon a specific order of removal, and must not reassign an entity that has been
orphaned to another relationship or otherwise attempt to persist it.
Table 38
OneToOne Annotation Elements
Type
Name
Description
Default
Class
targetEntity
(Optional) The entity class that is the target of
the association.
The type of the field or
property that stores the
association.
CascadeType[]
cascade
(Optional) The operations that must be cascaded to the target of the association.
No operations are cascaded.
FetchType
fetch
(Optional) Whether the association should be
lazily loaded or must be eagerly fetched. The
EAGER strategy is a requirement on the persistence provider runtime that the associated entity
must be eagerly fetched. The LAZY strategy is
a hint to the persistence provider runtime.
EAGER
boolean
optional
(Optional) Whether the association is optional.
If set to false then a non-null relationship must
always exist.
true
[114] If the parent is detached or new or was previously removed before the orphan was associated with it, the remove operation is not
applied to the entity being orphaned.
4/2/13
476
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
Type
Name
Description
String
mappedBy
(Optional) The field or property that owns the
relationship. The mappedBy element is only
specified on the inverse (non-owning) side of
the association.
boolean
orphanRemoval
(Optional) Whether to apply the remove operation to entities that have been removed from the
relationship and to cascade the remove operation to those entities.
Default
false
Example 1: One-to-one association that maps a foreign key column.
On Customer class:
@OneToOne(optional=false)
@JoinColumn(
name="CUSTREC_ID", unique=true, nullable=false, updatable=false)
public CustomerRecord getCustomerRecord() { return customerRecord; }
On CustomerRecord class:
@OneToOne(optional=false, mappedBy="customerRecord")
public Customer getCustomer() { return customer; }
Example 2: One-to-one association where both source and target share the same primary key values.
On Employee class:
@Entity
public class Employee {
@Id Integer id;
}
@OneToOne(orphanRemoval=true)
@MapsId
EmployeeInfo info;
...
On EmployeeInfo class:
@Entity
public class EmployeeInfo {
@Id Integer id;
...
}
JSR-338 Final Release
477
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
Example 3: One-to-one association from an embeddable class to another entity.
@Entity
public class Employee {
@Id int id;
@Embedded LocationDetails location;
...
}
@Embeddable
public class LocationDetails {
int officeNumber;
@OneToOne ParkingSpot parkingSpot;
...
}
@Entity
public class ParkingSpot {
@Id int id;
String garage;
@OneToOne(mappedBy="location.parkingSpot") Employee assignedTo;
...
}
11.1.42 OrderBy Annotation
The OrderBy annotation specifies the ordering the elements of a collection-valued association or element collection are to have when the association or collection is retrieved.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface OrderBy {
String value() default "";
}
The syntax of the value ordering element is an orderby_list, as follows:
orderby_list::= orderby_item [,orderby_item]*
orderby_item::= [property_or_field_name] [ASC | DESC]
If orderby_list is not specified or if ASC or DESC is not specified, ASC (ascending order) is assumed.
If the ordering element is not specified for an entity association, ordering by the primary key of the
associated entity is assumed.[115]
A property or field name specified as an orderby_item must correspond to a basic persistent property
or field of the associated class or embedded class within it. The properties or fields used in the ordering
must correspond to columns for which comparison operators are supported.
[115] If the primary key is a composite primary key, the precedence of ordering among the attributes within the primary key is not
futher defined. To assign such a precedence within these attributes, each of the individual attributes must be specified as an
orderby_item.
4/2/13
478
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
The dot (".") notation is used to refer to an attribute within an embedded attribute. The value of each
identifier used with the dot notation is the name of the respective embedded field or property.
The OrderBy annotation may be applied to an element collection. When OrderBy is applied to an
element collection of basic type, the ordering will be by value of the basic objects and the
property_or_field_name is not used.[116] When specifying an ordering over an element collection of
embeddable type, the dot notation must be used to specify the attribute or attributes that determine the
ordering.
The OrderBy annotation is not used when an order column is specified. See section 11.1.43.
Table 39 lists the annotation elements that may be specified for the OrderBy annotation.
Table 39
OrderBy Annotation Elements
Type
Name
Description
Default
String
value
(Optional) The list of attributes (optionally qualified with
ASC or DESC) whose values are used in the ordering.
Ascending ordering by the primary key.
Example 1:
@Entity public class Course {
...
@ManyToMany
@OrderBy("lastname ASC")
public List<Student> getStudents() {...};
...
}
Example 2:
@Entity public class Student {
...
@ManyToMany(mappedBy="students")
@OrderBy // PK is assumed
public List<Course> getCourses() {...};
...
}
Example 3:
@Entity public class Person {
...
@ElementCollection
@OrderBy("zipcode.zip, zipcode.plusFour")
public Set<Address> getResidences() {...};
...
}
[116] In all other cases when OrderBy is applied to an element collection, the property_or_field_name must be specified.
JSR-338 Final Release
479
4/2/13
Oracle
Metadata for Object/Relational Mapping
@Embeddable
protected
protected
protected
@Embedded
}
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
public class Address {
String street;
String city;
String state;
protected Zipcode zipcode;
@Embeddable public class Zipcode {
protected String zip;
protected String plusFour;
}
11.1.43 OrderColumn Annotation
The OrderColumn annotation specifies a column that is used to maintain the persistent order of a list.
The persistence provider is responsible for maintaining the order upon retrieval and in the database. The
persistence provider is responsible for updating the ordering upon flushing to the database to reflect any
insertion, deletion, or reordering affecting the list. The OrderColumn annotation may be specified on
a one-to-many or many-to-many relationship or on an element collection. The OrderColumn annotation is specified on the side of the relationship that references the collection that is to be ordered. The
order column is not visible as part of the state of the entity or embeddable class.[117]
The OrderBy annotation is not used when OrderColumn is specified.
Table 40 lists the annotation elements that may be specified for the OrderColumn annotation and
their default values.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface OrderColumn {
String name() default "";
boolean nullable() default true;
boolean insertable() default true;
boolean updatable() default true;
String columnDefinition() default "";
}
If name is not specified, the column name is the concatenation of the following: the name of the referencing relationship property or field of the referencing entity or embeddable class; "_"; "ORDER".
The order column must be of integral type. The persistence provider must maintain a contiguous
(non-sparse) ordering of the values of the order column when updating the association or element collection. The order column value for the first element of the list must be 0.
[117] The OrderBy annotation should be used for ordering that is visible as persistent state and maintained by the application.
4/2/13
480
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Table 40
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
OrderColumn Annotation Elements
Type
Name
Description
Default
String
name
(Optional) The name of the ordering column.
The concatenation of the name of
the referencing property or field;
"_"; "ORDER".
boolean
nullable
(Optional) Whether the database column
is nullable.
true
boolean
insertable
(Optional) Whether the column is
included in SQL INSERT statements
generated by the persistence provider.
true
boolean
updatable
(Optional) Whether the column is
included in SQL UPDATE statements
generated by the persistence provider.
true
String
columnDefinition
(Optional) The SQL fragment that is
used when generating the DDL for the
column.
Generated SQL to create a column
of the inferred type.
Example 1:
@Entity
public class CreditCard {
@Id long ccNumber;
}
@OneToMany // unidirectional
@OrderColumn
List<CardTransaction> transactionHistory;
...
Example 2:
@Entity public class Course {
...
@ManyToMany
@JoinTable(name="COURSE_ENROLLMENT")
public Set<Student> getStudents() {...};
...
@ManyToMany // unidirectional
@JoinTable(name="WAIT_LIST")
@OrderColumn(name="WAITLIST_ORDER")
public List<Student> getWaitList() {...}
}
@Entity public class Student {
...
@ManyToMany(mappedBy="students")
public Set<Course> getCourses() {...};
...
}
JSR-338 Final Release
481
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
Example of querying the ordered list:
SELECT w
FROM course c JOIN c.waitlist w
WHERE c.name = "geometry" AND INDEX(w) = 0
11.1.44 PrimaryKeyJoinColumn Annotation
The PrimaryKeyJoinColumn annotation specifies a primary key column that is used as a foreign
key to join to another table.
The PrimaryKeyJoinColumn annotation is used to join the primary table of an entity subclass in
the JOINED mapping strategy to the primary table of its superclass; it is used within a SecondaryTable annotation to join a secondary table to a primary table; and it may be used in a OneToOne
mapping in which the primary key of the referencing entity is used as a foreign key[118] to the referenced entity[119].
The foreignKey element is used to specify or control the generation of a foreign key constraint for
the primary key join column when table generation is in effect. If the foreignKey element is not
specified, the persistence provider’s default foreign key strategy will apply.
Table 41 lists the annotation elements that may be specified for the PrimaryKeyJoinColumn annotation and their default values.
If no PrimaryKeyJoinColumn annotation is specified for a subclass in the JOINED mapping strategy, the foreign key columns are assumed to have the same names as the primary key columns of the
primary table of the superclass.
@Target({TYPE, METHOD, FIELD}) @Retention(RUNTIME)
public @interface PrimaryKeyJoinColumn {
String name() default "";
String referencedColumnName() default "";
String columnDefinition() default "";
ForeignKey foreignKey() default @ForeignKey(PROVIDER_DEFAULT);
}
[118] It is not expected that a database foreign key be defined for the OneToOne mapping, as the OneToOne relationship may be
defined as “optional=true”.
[119] The derived id mechanisms described in section 2.4.1.1 are now to be preferred over PrimaryKeyJoinColumn for the OneToOne
mapping case.
4/2/13
482
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Table 41
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
PrimaryKeyJoinColumn Annotation Elements
Type
Name
Description
Default
String
name
(Optional) The name of the primary key column of the current
table.
The same name as the primary key
column of the primary table of the
superclass (JOINED mapping strategy); the same name as the primary
key column of the primary table
(SecondaryTable mapping); or the
same name as the primary key column for the table for the referencing
entity (OneToOne mapping).
String
referencedColumnName
(Optional) The name of the primary key column of the table
being joined to.
The same name as the primary key
column of the primary table of the
superclass (JOINED mapping strategy); the same name as the primary
key column of the primary table
(SecondaryTable mapping); or the
same name as the primary key column of the table for the referenced
entity (OneToOne mapping).
String
columnDefinition
(Optional) The SQL fragment that
is used when generating the DDL
for the column. This should not be
specified for a OneToOne primary
key association.
Generated SQL to create a column
of the inferred type.
ForeignKey
foreignKey
(Optional) The foreign key constraint specification for the join
column. This is used only if table
generation is in effect.
Provider’s default
Example: Customer and ValuedCustomer subclass
@Entity
@Table(name="CUST")
@Inheritance(strategy=JOINED)
@DiscriminatorValue("CUST")
public class Customer { ... }
@Entity
@Table(name="VCUST")
@DiscriminatorValue("VCUST")
@PrimaryKeyJoinColumn(name="CUST_ID")
public class ValuedCustomer extends Customer { ... }
JSR-338 Final Release
483
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
11.1.45 PrimaryKeyJoinColumns Annotation
Composite foreign keys are supported by means of the PrimaryKeyJoinColumns annotation. The
PrimaryKeyJoinColumns annotation groups PrimaryKeyJoinColumn annotations.
@Target({TYPE, METHOD, FIELD}) @Retention(RUNTIME)
public @interface PrimaryKeyJoinColumns {
PrimaryKeyJoinColumn[] value();
ForeignKey foreignKey() default @ForeignKey(PROVIDER_DEFAULT);
}
The foreignKey element is used to specify or control the generation of a foreign key constraint for
the columns corresponding to the PrimaryKeyJoinColumn elements referenced by the value element when table generation is in effect. If both this element and the foreignKey element of any of
the PrimaryKeyJoinColumn elements are specified, the behavior is undefined. If no foreignKey annotation element is specified in either location, the persistence provider's default foreign key
strategy will apply.
Table 42 lists the annotation elements that may be specified for the PrimaryKeyJoinColumns
annotation.
Table 42
PrimaryKeyJoinColumns Annotation Elements
Type
Name
Description
PrimaryKeyJoinColumn[]
value
(Required) The primary key join columns.
ForeignKey
foreignKey
(Optional) The foreign key constraint specification for the
join columns. This is used only if table generation is in
effect.
Default
Provider’s default
Example 1: ValuedCustomer subclass
@Entity
@Table(name="VCUST")
@DiscriminatorValue("VCUST")
@PrimaryKeyJoinColumns({
@PrimaryKeyJoinColumn(name="CUST_ID",
referencedColumnName="ID"),
@PrimaryKeyJoinColumn(name="CUST_TYPE",
referencedColumnName="TYPE")
})
public class ValuedCustomer extends Customer { ... }
4/2/13
484
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
Example 2: OneToOne relationship between Employee and EmployeeInfo classes.[120]
public class EmpPK {
public Integer id;
public String name;
}
@Entity
@IdClass(com.acme.EmpPK.class)
public class Employee {
@Id Integer id;
@Id String name;
@OneToOne
@PrimaryKeyJoinColumns({
@PrimaryKeyJoinColumn(name="ID",
referencedColumnName="EMP_ID"),
@PrimaryKeyJoinColumn(name="NAME",
referencedColumnName="EMP_NAME")})
EmployeeInfo info;
}
...
@Entity
@IdClass(com.acme.EmpPK.class)
public class EmployeeInfo {
@Id @Column(name="EMP_ID")
Integer id;
@Id @Column(name="EMP_NAME")
String name;
}
...
11.1.46 SecondaryTable Annotation
The SecondaryTable annotation is used to specify a secondary table for the annotated entity class.
If no SecondaryTable annotation is specified, it is assumed that all persistent fields or properties of
the entity are mapped to the primary table. Specifying one or more secondary tables indicates that the
data for the entity class is stored across multiple tables.
Table 43 lists the annotation elements that may be specified for the SecondaryTable annotation and
their default values.
[120]Note that the derived identity mechanisms decribed in section 2.4.1.1 is now preferred to the use of PrimaryKeyJoinColumn for
this case.
JSR-338 Final Release
485
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
If no primary key join columns are specified, the join columns are assumed to reference the primary key
columns of the primary table, and have the same names and types as the referenced primary key columns of the primary table.
The foreignKey element is used to specify or control the generation of a foreign key constraint for
the columns corresponding to the pkJoinColumns element when table generation is in effect. If both
this element and the foreignKey element of any of the pkJoinColumns elements are specified,
the behavior is undefined. If no foreignKey annotation element is specified in either location, the
persistence provider's default foreign key strategy will apply.
@Target({TYPE}) @Retention(RUNTIME)
public @interface SecondaryTable {
String name();
String catalog() default "";
String schema() default "";
PrimaryKeyJoinColumn[] pkJoinColumns() default {};
ForeignKey foreignKey() default @ForeignKey(PROVIDER_DEFAULT);
UniqueConstraint[] uniqueConstraints() default {};
Index[] indexes() default {};
}
Table 43
4/2/13
SecondaryTable Annotation Elements
Type
Name
Description
String
name
(Required) The name of the table.
String
catalog
(Optional) The catalog of the table.
Default catalog
String
schema
(Optional) The schema of the table.
Default schema for user
PrimaryKeyJoinColumn[]
pkJoinColumns
(Optional) The columns that are
used to join with the primary table.
Column(s) of the same
name(s) as the primary key
column(s) in the primary
table
ForeignKey
foreignKey
(Optional) The foreign key constraint for the join column. This is
used only if table generation is in
effect.
Provider’s default
UniqueConstraint[]
uniqueConstraints
(Optional) Unique constraints that
are to be placed on the table. These
are typically only used if table generation is in effect. These constraints
apply in addition to any constraints
specified by the Column and JoinColumn annotations and constraints
entailed by primary key mappings.
No additional constraints
Index[]
indexes
(Optional) Indexes for the table.
These are only used if table generation is in effect.
No additional indexes
486
Default
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
Example 1: Single secondary table with a single primary key column.
@Entity
@Table(name="CUSTOMER")
@SecondaryTable(
name="CUST_DETAIL",
[email protected](name="CUST_ID")
)
public class Customer { ... }
Example 2: Single secondary table with multiple primary key columns.
@Entity
@Table(name="CUSTOMER")
@SecondaryTable(
name="CUST_DETAIL",
pkJoinColumns={
@PrimaryKeyJoinColumn(name="CUST_ID"),
@PrimaryKeyJoinColumn(name="CUST_TYPE")
})
public class Customer { ... }
11.1.47 SecondaryTables Annotation
The SecondaryTables annotation is used to specify multiple secondary tables for an entity.
@Target({TYPE}) @Retention(RUNTIME)
public @interface SecondaryTables {
SecondaryTable[] value();
}
Table 44 lists the annotation elements that may be specified for the SecondaryTables annotation.
Table 44
SecondaryTables Annotation Elements
Type
Name
Description
SecondaryTable[]
value
(Required) The secondary tables that are used to map the
entity class.
Default
Example 1: Multiple secondary tables assuming primary key columns are named the same in all tables.
@Entity
@Table(name="EMPLOYEE")
@SecondaryTables({
@SecondaryTable(name="EMP_DETAIL"),
@SecondaryTable(name="EMP_HIST")
})
public class Employee { ... }
JSR-338 Final Release
487
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
Example 2: Multiple secondary tables with differently named primary key columns.
@Entity
@Table(name="EMPLOYEE")
@SecondaryTables({
@SecondaryTable(
name="EMP_DETAIL",
[email protected](name="EMPL_ID")),
@SecondaryTable(
name="EMP_HIST",
[email protected](name="EMPLOYEE_ID"))
})
public class Employee { ... }
11.1.48 SequenceGenerator Annotation
The SequenceGenerator annotation defines a primary key generator that may be referenced by
name when a generator element is specified for the GeneratedValue annotation. A sequence generator may be specified on the entity class or on the primary key field or property. The scope of the generator name is global to the persistence unit (across all generator types).
Table 45 lists the annotation elements that may be specified for the SequenceGenerator annotation
and their default values.
@Target({TYPE, METHOD, FIELD}) @Retention(RUNTIME)
public @interface SequenceGenerator {
String name();
String sequenceName() default "";
String catalog() default "";
String schema() default "";
int initialValue() default 1;
int allocationSize() default 50;
}
Table 45
4/2/13
SequenceGenerator Annotation Elements
Type
Name
Description
String
name
(Required) A unique generator name that can be referenced by
one or more classes to be the generator for primary key values.
String
sequenceName
(Optional) The name of the database sequence object from which
to obtain primary key values.
A providerchosen
value
String
catalog
(Optional) The catalog of the sequence generator.
Default catalog
String
schema
(Optional) The schema of the sequence generator.
Default
schema for
user
int
initialValue
(Optional) The value from which the sequence object is to start
generating.
1
488
Default
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
Type
Name
Description
Default
int
allocationSize
(Optional) The amount to increment by when allocating sequence
numbers from the sequence.
50
Example:
@SequenceGenerator(name="EMP_SEQ", allocationSize=25)
11.1.49 Table Annotation
The Table annotation specifies the primary table for the annotated entity. Additional tables may be
specified by using the SecondaryTable or SecondaryTables annotation.[121]
Table 46 lists the annotation elements that may be specified for the Table annotation and their default
values.
If no Table annotation is specified for an entity class, the default values defined in Table 46 apply.
@Target({TYPE}) @Retention(RUNTIME)
public @interface Table {
String name() default "";
String catalog() default "";
String schema() default "";
UniqueConstraint[] uniqueConstraints() default {};
Index[] indexes() default {};
}
Table 46
Table Annotation Elements
Type
Name
Description
Default
String
name
(Optional) The name of the table.
Entity name
String
catalog
(Optional) The catalog of the table.
Default catalog
String
schema
(Optional) The schema of the table.
Default schema
for user
UniqueConstraint[]
uniqueConstraints
(Optional) Unique constraints that are to be
placed on the table. These are only used if table
generation is in effect. These constraints apply
in addition to any constraints specified by the
Column and JoinColumn annotations and constraints entailed by primary key mappings.
No additional
constraints
Index[]
indexes
(Optional) Indexes for the table. These are only
used if table generation is in effect.
No additional
indexes
[121]When a joined inheritance strategy is used, the Table annotation is used to specify a primary table for the subclass-specific state if
the default is not used.
JSR-338 Final Release
489
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
Example:
@Entity
@Table(name="CUST", schema="RECORDS")
public class Customer { ... }
11.1.50 TableGenerator Annotation
The TableGenerator annotation defines a primary key generator that may be referenced by name
when a generator element is specified for the GeneratedValue annotation. A table generator may be
specified on the entity class or on the primary key field or property. The scope of the generator name is
global to the persistence unit (across all generator types).
Table 47 lists the annotation elements that may be specified for the TableGenerator annotation and
their default values.
The table element specifies the name of the table that is used by the persistence provider to store generated primary key values for entities. An entity type will typically use its own row in the table for the
generation of primary key values. The primary key values are normally positive integers.
@Target({TYPE, METHOD, FIELD}) @Retention(RUNTIME)
public @interface TableGenerator {
String name();
String table() default "";
String catalog() default "";
String schema() default "";
String pkColumnName() default "";
String valueColumnName() default "";
String pkColumnValue() default "";
int initialValue() default 0;
int allocationSize() default 50;
UniqueConstraint[] uniqueConstraints() default {};
Index[] indexes() default {};
}
Table 47
4/2/13
TableGenerator Annotation Elements
Type
Name
Description
String
name
(Required) A unique generator name that
can be referenced by one or more classes
to be the generator for primary key values.
String
table
(Optional) Name of table that stores the
generated primary key values.
Name is chosen by persistence provider
String
catalog
(Optional) The catalog of the table.
Default catalog
String
schema
(Optional) The schema of the table.
Default schema for user
String
pkColumnName
(Optional) Name of the primary key column in the table.
A provider-chosen name
490
Default
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
Type
Name
Description
Default
String
valueColumnName
(Optional) Name of the column that stores
the last value generated.
A provider-chosen name
String
pkColumnValue
(Optional) The primary key value in the
generator table that distinguishes this set
of generated values from others that may
be stored in the table.
A provider-chosen value to
store in the primary key column of the generator table
int
initialValue
(Optional) The value used to initialize the
column that stores the last value generated.
0
int
allocationSize
(Optional) The amount to increment by
when allocating numbers from the generator.
50
UniqueConstraint[]
uniqueConstraints
(Optional) Unique constraints that are to
be placed on the table. These are only used
if table generation is in effect. These constraints apply in addition to primary key
constraints .
No additional constraints
Index[]
indexes
(Optional) Indexes for the table. These are
only used if table generation is in effect.
No additional indexes
Example 1:
@Entity public class Employee {
...
@TableGenerator(
name="empGen",
table="ID_GEN",
pkColumnName="GEN_KEY",
valueColumnName="GEN_VALUE",
pkColumnValue="EMP_ID",
allocationSize=1)
@Id
@GeneratedValue(strategy=TABLE, generator="empGen")
int id;
...
}
Example 2:
@Entity public class Address {
...
@TableGenerator(
name="addressGen",
table="ID_GEN",
pkColumnName="GEN_KEY",
valueColumnName="GEN_VALUE",
pkColumnValue="ADDR_ID")
@Id
@GeneratedValue(strategy=TABLE, generator="addressGen")
int id;
...
}
JSR-338 Final Release
491
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final Release
Annotations for Object/Relational Mapping
11.1.51 Temporal Annotation
The Temporal annotation must be specified for persistent fields or properties of type
java.util.Date and java.util.Calendar unless a converter is being applied. It may only be
specified for fields or properties of these types.
The Temporal annotation may be used in conjunction with the Basic annotation, the Id annotation,
or the ElementCollection[122] annotation (when the element collection value is of such a temporal type).
The TemporalType enum defines the mapping for these temporal types.
public enum TemporalType {
DATE, //java.sql.Date
TIME, //java.sql.Time
TIMESTAMP //java.sql.Timestamp
}
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface Temporal {
TemporalType value();
}
Table 48 lists the annotation elements that may be specified for the Temporal annotation and their
default values.
Table 48
Temporal Annotation Elements
Type
Name
Description
TemporalType
value
(Required) The type used in mapping
java.util.Date or java.util.Calendar.
Default
Example:
@Embeddable
public class EmploymentPeriod {
@Temporal(DATE) java.util.Date startDate;
@Temporal(DATE) java.util.Date endDate;
...
}
[122]If the element collection is a Map, this applies to the map value.
4/2/13
492
JSR-338 Final Release
Oracle
Annotations for Object/Relational Mapping
Java Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
11.1.52 Transient Annotation
The Transient annotation is used to annotate a property or field of an entity class, mapped superclass, or embeddable class. It specifies that the property or field is not persistent.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface Transient {}
Example:
@Entity
public class Employee {
@Id int id;
@Transient User currentUser;
...
}
11.1.53 UniqueConstraint Annotation
The UniqueConstraint annotation is used to specify that a unique constraint is to be included in
the generated DDL for a primary or secondary table.
Table 49 lists the annotation elements that may be specified for the UniqueConstraint annotation.
@Target({}) @Retention(RUNTIME)
public @interface UniqueConstraint {
String name() default "";
String[] columnNames();
}
Table 49
UniqueConstraint Annotation Elements
Type
Name
Description
Default
String
name
(Optional) Constraint name.
A provider-chosen
name.
String[]
columnNames
(Required) An array of the column names that make up the
constraint.
Example:
@Entity
@Table(
name="EMPLOYEE",
uniqueConstraints=
@UniqueConstraint(columnNames={"EMP_ID", "EMP_NAME"})
)
public class Employee { ... }
JSR-338 Final Release
493
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final ReleaseObject/Relational Metadata Used in Schema Gen-
11.1.54 Version Annotation
The Version annotation specifies the version field or property of an entity class that serves as its optimistic lock value. The version is used to ensure integrity when performing the merge operation and for
optimistic concurrency control.
Only a single Version property or field should be used per class; applications that use more than one
Version property or field will not be portable.
The Version property should be mapped to the primary table for the entity class; applications that
map the Version property to a table other than the primary table will not be portable.
In general, fields or properties that are specified with the Version annotation should not be updated
by the application.[123]
The following types are supported for version properties: int, Integer, short, Short, long,
Long, Timestamp.
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface Version {}
Example:
@Version
@Column(name="OPTLOCK")
protected int getVersionNum() { return versionNum; }
11.2 Object/Relational Metadata Used in Schema Generation
The following annotations and XML elements define or control the generation of database objects. If
schema generation is in effect, the persistence provider must observe the mapping information specified
by these annotations and their corresponding XML elements. Unless otherwise specified, all elements
of these annotations are observed in the schema generation process.
CollectionTable
Column
DiscriminatorColumn
EmbeddedId
Enumerated, MapKeyEnumerated
ForeignKey
GeneratedValue
Id
Index
[123]See, however, section 4.10.
4/2/13
494
JSR-338 Final Release
Oracle
Object/Relational Metadata Used in Schema GenerationJava Persistence 2.1, Final Release
Metadata for Object/Relational Mapping
Inheritance
JoinColumn
JoinTable
Lob
MapKeyColumn
MapKeyJoinColumn
OrderColumn
PrimaryKeyJoinColumn
SecondaryTable
SequenceGenerator
Table
TableGenerator
Temporal, MapKeyTemporal
UniqueConstraint
Version
In some cases, these annotations and elements may be specified explicitly, while in other cases they may
be implied by the default values of other annotations or elements. For example, by default a table is
generated corresponding to an entity and bears the same name as that assigned to the entity (which in
turn may have been defaulted from the name of the entity class).
The naming of database objects is determined by the defaulting rules and the explicit names used in
annotations and/or XML. The names of database objects must be treated in conformance with the
requirements of section 2.13.
The metadata annotations and corresponding XML elements that result in generated objects are as follows.
11.2.1 Table-level elements
The following annotations (and corresponding XML elements) specify the creation of tables. The rules
for their naming, columns, and other properties are defined in the referenced sections of this specification:
11.2.1.1 Table
By default, a table is created for every top-level entity and, by default, includes columns corresponding
to the basic and embedded attributes of the entity and the foreign keys to the tables of related entities.
These columns include columns that result from the use of mapped superclasses, if any. The SecondaryTable annotation, in conjunction with the use of the table element of the Column and JoinColumn annotations, is used to override this mapping to partition the state of an entity across multiple
tables.
JSR-338 Final Release
495
4/2/13
Oracle
Metadata for Object/Relational Mapping
Java Persistence 2.1, Final ReleaseObject/Relational Metadata Used in Schema Gen-
The mapping of the columns of a table is controlled by the Column and JoinColumn annotations.
When entity state is inherited from a mapped superclass, the AttributeOverride and AssociationOverride annotations may be used to further control the column-level mapping of inherited
state. T