How to override a Magento core controller

If you want to override a core controller on Magento in order to add other customActions, it is really quick and easy to do so. Here are the files that you have to take into account:

• The controller you want to override: /app/code/core/Catalog/controllers/ProductController.php
• The xml file to enable the module: /app/etc/modules/Company_Module.xml
• The controller xml file definition: /app/code/local/Company/Module/etc/config.xml
• The overridden controller: /app/code/local/Company/Module/controllers/ProductController.php

First of all, you have to enable the module on the /app/etc/modules directory. This file would be Company_Module.xml and inside that:

<?xml version="1.0"?>
<config>
 <modules>
  <Company_Module>
   <active>true</active>
   <codePool>local</codePool>
  </Company_Module>
 </modules>
</config> 

Now it’s time to create the config.xml file that will override the core controller:

<?xml version="1.0"?>
<config>
 <frontend>
  <routers>
   <catalog>
    <args>
     <modules>
      <Company_Module before="Mage_Catalog">Company_Module</Company_Module>
     </modules>
    </args>
   </catalog>
  </routers>
 </frontend>
</config>

If your controller is placed in a folder inside the folder controller, you have to change the reference. For example, if your module is in the folder controllers/Folder, then the config.xml should look like this:

<?xml version="1.0"?>
<config>
 <frontend>
  <routers>
   <catalog>
    <args>
     <modules>
      <Company_Module before="Mage_Catalog">Company_Module_Folder</Company_Module>
     </modules>
    </args>
   </catalog>
  </routers>
 </frontend>
</config>

Finally, we can create the class that will add/change actions to the core controller:

class Smile_Catalog_ProductController extends Mage_Core_Controller_Front_Action
{
    public function customAction()
    {
       /* .... */
    }
}

Now you should check if it your custom action works. You can call that function, in this case, using the route: http://yourweb.com/catalog/product/customAction/

• There are also other ways of overriding magento core modules, for example when you want to override a magento core block class.
• If you want to override a magento admin controller, take a look at this post.