Standard Controllers. salesforce Visualforce Developer Guide

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CHAPTER 5 Standard Controllers

A Visualforce controller is a set of instructions that specify what happens when a user interacts with the components specified in associated

Visualforce markup, such as when a user clicks a button or link. Controllers also provide access to the data that should be displayed in a page, and can modify component behavior.

The Force.com platform provides a number of standard controllers that contain the same functionality and logic that are used for standard

Salesforce pages. For example, if you use the standard Accounts controller, clicking a Save button in a Visualforce page results in the same behavior as clicking Save on a standard Account edit page.

A standard controller exists for every Salesforce object that can be queried using the Force.com API.

The following topics include additional information about using standard controllers:

•

Associating a Standard Controller with a Visualforce Page

•

Accessing Data with a Standard Controller

•

Using Standard Controller Actions

•

Validation Rules and Standard Controllers

•

Styling Pages that Use Standard Controllers

•

Checking for Object Accessibility

•

Custom Controllers and Controller Extensions

Associating a Standard Controller with a Visualforce Page

To associate a standard controller with a Visualforce page, use the standardController

attribute on the

<apex:page >

tag and assign it the name of any Salesforce object that can be queried using the Force.com API.

For example, to associate a page with the standard controller for a custom object named MyCustomObject, use the following markup:

<apex:page standardController= "MyCustomObject__c" >

</apex:page >

Note:

When you use the standardController

attribute on the

<apex:page >

tag, you cannot use the controller attribute at the same time.

Accessing Data with a Standard Controller

Every standard controller includes a getter method that returns the record specified by the id

query string parameter in the page URL.

This method allows the associated page markup to reference fields on the context record by using

object}

syntax, where

object

is the lowercase name of the object associated with the controller. For example, a page that uses the Account standard controller can use

{!account.name}

to return the value of the name

field on the account that is currently in context.

Standard Controllers Using Standard Controller Actions

Note: For the getter method to succeed, the record specified by the id

query string parameter in the URL must be of the same type as the standard controller. For example, a page that uses the Account standard controller can only return an account record.

If a contact record ID is specified by the id

query string parameter, no data is returned by the

{!account}

expression.

As with queries in the Force.com API, you can use merge field syntax to retrieve data from related records:

•

You can traverse up to five levels of child-to-parent relationships. For example, if using the Contact standard controller, you can use

{!contact.Account.Owner.FirstName}

(a three-level child-to-parent relationship) to return the name of the owner of the account record that is associated with the contact.

•

You can traverse one level of parent-to-child relationships. For example, if using the Account standard controller, you can use

{!account.Contacts}

to return an array of all contacts associated with the account that is currently in context.

Using Standard Controller Actions

Action methods perform logic or navigation when a page event occurs, such as when a user clicks a button, or hovers over an area of the page. Action methods can be called from page markup by using

{! }

notation in the action

parameter of one of the following tags:

•

<apex:commandButton >

creates a button that calls an action

•

<apex:commandLink >

creates a link that calls an action

•

<apex:actionPoller >

periodically calls an action

•

<apex:actionSupport >

makes an event (such as “onclick”, “onmouseover”, and so on) on another, named component, call an action

•

<apex:actionFunction >

defines a new JavaScript function that calls an action

•

<apex:page >

calls an action when the page is loaded

The following table describes the action methods that are supported by all standard controllers. You can associate these actions with any Visualforce component that includes an action

attribute.

Action

save quicksave edit delete cancel list

Description

Inserts a new record or updates an existing record if it is currently in context. After this operation is finished, the save

action returns the user to the original page (if known), or navigates the user to the detail page for the saved record.

Inserts a new record or updates an existing record if it is currently in context. Unlike the save

action, this page does not redirect the user to another page.

Navigates the user to the edit page for the record that is currently in context. After this operation is finished, the edit

action returns the user to the page where the user originally invoked the action.

Deletes the record that is currently in content. After this operation is finished, the delete

action either refreshes the page or sends the user to tab for the associated object.

Aborts an edit operation. After this operation is finished, the cancel

action returns the user to the page where the user originally invoked the edit.

Returns a PageReference object of the standard list page, based on the most recently used list filter for that object. For example, if the standard controller is contact

, and the last filtered list that the user viewed is New Last Week, the contacts created in the last week are displayed.

Standard Controllers Validation Rules and Standard Controllers

For example, the following page allows you to update an account. When you click Save, the save

action is triggered on the standard controller, and the account is updated.

<apex:page standardController= "Account" >

<apex:form >

<apex:pageBlock title= "My Content" mode= "edit" >

<apex:pageBlockButtons >

<apex:commandButton action= "{!save}" value= "Save" />

</apex:pageBlockButtons >

<apex:pageBlockSection title= "My Content Section" columns= "2" >

<apex:inputField value= "{!account.name}" />

<apex:inputField value= "{!account.site}" />

<apex:inputField value= "{!account.type}" />

<apex:inputField value= "{!account.accountNumber}" />

</apex:pageBlockSection >

</apex:pageBlock >

</apex:form >

</apex:page >

Note: Remember, for this page to display account data, the ID of a valid account record must be specified as a query parameter in the URL for the page. For example: https://

Salesforce_instance

/apex/myPage?id=001x000xxx3Jsxb

Displaying Field Values with Visualforce on page 18 has more information about retrieving the ID of a record.

Note: Command buttons and links that are associated with save

, quicksave

, edit

, or delete

actions in a standard controller are only rendered if the user has the appropriate permissions. Likewise, if no particular record is associated with a page, command buttons and links associated with the edit

and delete

actions are not rendered.

Validation Rules and Standard Controllers

If a user enters data on a Visualforce page that uses a standard controller, and that data causes a validation rule error, the error can be displayed on the Visualforce page. If the validation rule error location is a field associated with an

<apex:inputField >

component, the error displays there. If the validation rule error location is set to the top of the page, use the

<apex:pageMessages >

<apex:messages >

component within the

<apex:page >

to display the error.

Styling Pages that Use Standard Controllers

Any page associated with a standard controller automatically inherits the style that is used for standard Salesforce pages associated with the specified object. That is, the tab for the specified object appears selected, and the associated color of the tab is used to style all page elements.

You can override the styling of a page that uses a standard controller with the tabStyle

attribute on the

<apex:page >

tag. For example, the following page uses the Account standard controller, but renders a page that highlights the Opportunities tab and uses the Opportunity tab's yellow coloring:

<apex:page standardController= "Account" tabStyle= "Opportunity" >

</apex:page >

Standard Controllers Checking for Object Accessibility

To use the styling associated with MyCustomObject:

<apex:page standardController= "Account" tabStyle= "MyCustomObject__c" >

</apex:page >

To use the styling associated with a custom Visualforce tab, set the attribute to the name (not label) of the tab followed by a double-underscore and the word tab. For example, to use the styling of a Visualforce tab with the name Source and a label Sources, use:

<apex:page standardController= "Account" tabStyle= "Source__tab" >

</apex:page >

Alternatively, you can override standard controller page styles with your own custom stylesheets and inline styles.

Checking for Object Accessibility

If a user has insufficient privileges to view an object, any Visualforce page that uses a controller to render that object will be inaccessible.

To avoid this error, you should ensure that your Visualforce components will only render if a user has access to the object associated with the controller.

You can check for the accessibility of an object like this:

{!$ObjectType.objectname.accessible}

This expression returns a true or false value.

For example, to check if you have access to the standard Lead object, use the following code:

{!$ObjectType.Lead.accessible}

For custom objects, the code is similar:

{!$ObjectType.MyCustomObject__c.accessible} where

MyCustomObject__c

is the name of your custom object.

To ensure that a portion of your page will display only if a user has access to an object, use the render

attribute on a component. For example, to display a page block if a user has access to the Lead object, you would do the following:

<apex:page standardController= "Lead" >