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 Force.com 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();
The following table is a non-exhaustive list of headers that are set on requests.
Header | Description |
---|---|
Host | The host name requested in the request URL. This header is always set on Force.com Site requests and My Domain requests. This header is optional on other requests when HTTP/1.0 is used instead of HTTP/1.1. |
Referer | The URL that is either included or linked to the current request's URL. This header is optional. |
User-Agent | The name, version, and extension support of the program that initiated this request, such as a Web browser. This header is optional and can be overridden in most browsers to be a different value. Therefore, this header should not be relied upon. |
CipherSuite | If this header exists and has a non-blank value, this means that the request is using HTTPS. Otherwise, the request is using HTTP. The contents of a non-blank value are not defined by this API, and can be changed without notice. |
X-Salesforce-SIP | The source IP address of the request. This header is always set on HTTP and HTTPS requests that are initiated outside of Salesforce's data centers. |
X-Salesforce-Forwarded-To | The fully qualified domain name of the Salesforce instance that is handling this request. This header is always set on HTTP and HTTPS requests that are initiated outside of Salesforce's data centers. |
The following 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 class MyController { public Account getAccount() { return [SELECT Id, Name FROM Account WHERE Id = :ApexPages.currentPage().getParameters().get('Id')]; } }
The following page markup calls the getAccount method from the controller above:
<apex:page controller="MyController"> <apex:pageBlock title="Retrieving Query String Parameters"> You are viewing the {!account.name} account. </apex:pageBlock> </apex:page>
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:
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.
The following 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; } }
The following page markup calls the save method from the controller above. 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>