‘How do I call Apex code from a Custom Button?’ is a simple question, however the answer is covered across various developers guides and general documentation…

Having answered a number of questions on StackExchange over the year or so I’ve been active on it, I thought I’d compile this how to guide as reference peace. Of course its littered with links to the  excellent Salesforce documentation, so please do dig into those as well.

The steps are as follows to add either a Detail or a List View  button (as illustrated below) to Standard or Custom Object. It’s well worth going through the topics and general reference guides I’ve linked in more detail. I’ve given some examples of my own, but there are also plenty of them in the help topics I’ve linked to if you need more examples.

Steps to Create a Custom Button that runs Apex Code

1. Create a Apex Extension Controller class as shown in the examples below.
2. Create a Visualforce page, using the ‘standardController‘ and ‘extensions‘ attributes on apex:page *
3. Create a Custom Button using the Visualforce page as its Content Source
4. Add the Custom Button to the appropriate Layout of the object
5. Use either the ‘action‘ attribute (see warning below) or apex:commandButton‘s on your page to invoke Apex logic.

* You must also use the ‘recordSetVar‘ attribute on apex:page if you wish to create List View button.

Detail Page Custom Button Template

Example page and class using apex:commandButton to invoke the logic.

<apex:page standardController="Test__c" extensions="DetailButtonController">
    <apex:form >
        <apex:commandButton value="Do something" action="{!doSomething}"/>
    </apex:form>
</apex:page>

Apex controller code.

public with sharing class DetailButtonController
{
    private ApexPages.StandardController standardController;

    public DetailButtonController(ApexPages.StandardController standardController)
    {
        this.standardController = standardController;
    }

    public PageReference doSomething()
    {
        // Apex code for handling record from a Detail page goes here
        Id recordId = standardController.getId();
        Test__c record = (Test__c) standardController.getRecord();
        return null;
    }
}

Or to have your Apex logic run as soon as the user presses the Custom Button use the action attribute.

<apex:page standardController="Test__c" extensions="DetailButtonController"
           action="{!doSomething}">

To add the Custom Button should look something like this…

List View Custom Button Template

Example page and class, using apex:commandButton to invoke the logic.

<apex:page standardController="Test__c" extensions="ListButtonController"
           recordSetVar="TestRecords">
    <apex:form >
        <apex:commandButton value="Do something" action="{!doSomething}"/>
    </apex:form>
</apex:page>

Apex controller code.

public with sharing class ListButtonController
{
    private ApexPages.StandardSetController standardSetController;

    public ListButtonController(ApexPages.StandardSetController standardSetController)
    {
        this.standardSetController = standardSetController;
    }

    public PageReference doSomething()
    {
        // Apex code for handling records from a List View goes here
        List<Test__c> listViewRecords =
            (List<Test__c>) standardSetController.getRecords();
        List<Test__c> selectedListViewRecords =
            (List<Test__c>) standardSetController.getSelected();
        Boolean hasMore = standardSetController.getHasNext();
        return null;
    }
}

Or to have your Apex logic run as soon as the user presses the Custom Button use the action attribute.

<apex:page standardController="Test__c" extensions="ListButtonController"
           action="{!doSomething}" recordSetVar="TestRecords">

To add the Custom Button should look something like this…

WARNING: Use of ‘action’ attribute on apex:page and CSRF Attacks.

If you use the ‘action‘ attribute as per step 4 your Apex code will execute as soon as the Custom Button is pressed. However if your Apex code performs database updates this is considered unsecured as its possible that your code will be open to a CSRF attack. See this excellent topic from Salesforce for more information. If this is your case its better to use the apex:commandButton option and provide a confirmation button to your user before invoking your Apex code.

Since its Summer’13 release, Salesforce have started to add some support to allow us to use the ‘action’ attribute safely, which gives a better user experience since there is no need for a confirmation button. Currently however, the new ‘Require CSRF protection on GET requests‘ checkbox on the Visualforce page is only considered when the page is used to override the standard Delete button on an object. Hopefully support for Custom Button will arrive soon!

Update: 31st July 2013

Here is a great blog on sharing your Apex Controller class between Detail and List pages, Using one page and controller for both a “Detail Page Button” and a “List Button”.