Add an Extension to a Visualforce Page

Tutorial #8: Inputting Data with Forms shows how to create a very simple form. In this lesson you will duplicate that page, adding the extension functionality:

1. Create a new Visualforce page called MyAccountWithExtension.
2. Use the following as the body of the page:

   <apex:page standardController="Account" extensions="MyExtension"> 
       <p>{!title}</p>
       <apex:form>
           <apex:inputField value="{!account.name}"/>
           <apex:commandButton action="{!save}" value="Save!"/>
       </apex:form>
   </apex:page>

3. Now access your page with a valid Account identifier passed in as a parameter. Your URL will look something like:https://na6.visual.force.com/apex/MyAccountWithExtension?id=0018000000MDfn1

What you’ll find is that your form pre-populates the input field with the name of the identified account. Great! And it also shows your fancy title with the account name and identifier.

When you save the page, you’ll notice that a new line appears above the form. Here’s what’s happening in your page:

• The attribute extensions="MyExtension" ensures that Visualforce instantiates a copy of your Apex class MyExtension, passing in a reference to the current controller (you’re using the standard controller for Account).
• The syntax {! title} instructs Visualforce to look for a method called getTitle() and insert the result of calling that method. Because there is such a method in your extension, Visualforce executes it and replaces the statement with the result.