PageReference Class

In a custom controller or controller extension, you can refer to or instantiate a PageReference in one of these ways.

• Page.existingPageName

  Refers to a PageReference for a Visualforce page that has already been saved in your organization. By referring to a page in this way, the platform recognizes that this controller or controller extension is dependent on the existence of the specified page and will prevent the page from being deleted while the controller or extension exists.

• PageReference pageRef = new PageReference('partialURL');

  Creates a PageReference to any page that is hosted on the Lightning platform. For example, setting 'partialURL' to '/apex/HelloWorld' refers to the Visualforce page located at http://mySalesforceInstance/apex/HelloWorld. Likewise, setting 'partialURL' to '/' + 'recordID' refers to the detail page for the specified record.

  This syntax is less preferable for referencing other Visualforce pages than Page.existingPageName because the PageReference is constructed at runtime, rather than referenced at compile time. Runtime references are not available to the referential integrity system. Consequently, the platform doesn't recognize that this controller or controller extension is dependent on the existence of the specified page and won't issue an error message to prevent user deletion of the page.

• PageReference pageRef = new PageReference('fullURL');

  Creates a PageReference for an external URL. For example:

  PageReference pageRef = new PageReference('http://www.google.com');

PageReference pageRef = ApexPages.currentPage();

This example shows how to use a PageReference object to retrieve a query string parameter in the current page URL. In this example, the getAccount method references the id query string parameter.

public with sharing class MyController {
   public Account getAccount() {
        return [SELECT Id, Name FROM Account WITH SECURITY_ENFORCED
                WHERE Id = :ApexPages.currentPage().getParameters().get('Id')];
    }
}

This page markup calls the getAccount method from that controller.

<apex:page controller="MyController">
    <apex:pageBlock title="Retrieving Query String Parameters">
        You are viewing the {!account.name} account.
    </apex:pageBlock>
</apex:page>

https://Visualforce_Url/apex/MyFirstPage?id=001D000000IRt53

The getAccount method uses an embedded SOQL query to return the account specified by the id parameter in the URL of the page. To access id, the getAccount method uses the ApexPages namespace.

• First the currentPage method returns the PageReference instance for the current page. PageReference returns a reference to a Visualforce page, including its query string parameters.
• Using the page reference, use the getParameters method to return a map of the specified query string parameter names and values.
• Then a call to the get method specifying id returns the value of the id parameter itself.

Any action method in a custom controller or controller extension can return a PageReference object as the result of the method. If the redirect attribute on the PageReference is set to true, the user navigates to the URL specified by the PageReference.

This example shows how this can be implemented with a save method. In this example, the PageReference returned by the save method redirects the user to the detail page for the account record that was just saved.

public class mySecondController {
    Account account;

    public Account getAccount() {
        if(account == null) account = new Account();
        return account;
    }

    public PageReference save() {
        // Add the account to the database. 
        insert account;
        // Send the user to the detail page for the new account.
        PageReference acctPage = new ApexPages.StandardController(account).view();
        acctPage.setRedirect(true);
        return acctPage;
    }
}

This page markup calls the save method from that controller. When a user clicks Save, he or she is redirected to the detail page for the account just created:

<apex:page controller="mySecondController" tabStyle="Account">
    <apex:sectionHeader title="New Account Edit Page" />
    <apex:form>
        <apex:pageBlock title="Create a New Account">
            <apex:pageBlockButtons location="bottom">
                <apex:commandButton action="{!save}" value="Save"/>
            </apex:pageBlockButtons>
            <apex:pageBlockSection title="Account Information">
                <apex:inputField id="accountName" value="{!account.name}"/>
                <apex:inputField id="accountSite" value="{!account.site}"/>
            </apex:pageBlockSection>
       </apex:pageBlock>
    </apex:form>
</apex:page>