Creating Your Own Event In Magento

First, we registered a new Module with Name Jeff_Helloworld:

#app/etc/modules/Jeff_Helloworld.xml
<?xml version="1.0"?>
<config>
    <modules>
        <Jeff_Helloworld>
            <active>true</active>
            <codePool>local</codePool>
        </Jeff_Helloworld>
    </modules>
</config>

Second, we create Jeff_Helloworld module by generating the folder app/code/local/Jeff/Helloworld/etc/config.xml file, which is shown as following:

#app/code/local/Jeff/Helloworld/etc/config.xml

<?xml version="1.0"?>
<config>
    <modules>
        <Jeff_Test>
            <version>0.1.0</version>
        </Jeff_Test>
    </modules>
    <global>
        <blocks>
            <helloworld>
                <class>Jeff_Helloworld_Block</class>
            </helloworld>
        </blocks>
        <helpers>
            <helloworld>
                <class>Jeff_Helloworld_Helper</class>
            </helloworld>
        </helpers>
        <models>
            <helloworld>
                <class>Jeff_Helloworld_Model</class>
            </helloworld>
        </models>
    </global>
    <frontend>
        <routers>
            <helloworld>
                <use>standard</use>
                <args>
                    <module>Jeff_Helloworld</module>
                    <frontName>helloworld</frontName>
                </args>
            </helloworld>
        </routers>
        <layout>
            <updates>
                <jeff_helloworld>
                    <file>jeff_helloworld.xml</file>
                </jeff_helloworld>
            </updates>
        </layout>
    </frontend>
</config>

In this file, we just tell magento, the name of new module and the locations of blocks, model and helper classes. We also register a route helloworld. So the URL (http://www.domain.com/helloworld/controller/action) will point to folder app/code/local/Jeff/ Helloworld/controllers/ControllerController.php

Third, we create sub-folder as app/code/local/Jeff/ Helloworld/controllers to put our Controller classes. The first Controller is named “IndexController” and the action is called “index”.

class Jeff_Helloworld_IndexController Extends Mage_Core_Controller_Front_Action {
       public function indexAction() {
           $this->loadLayout();
           $parameters = array(
               'product'=>Mage::getModel('catalog/product')->load(1), 
               'category'=>Mage::getModel('catalog/category')->load(10)
            );
           Mage::dispatchEvent('helloworld_register_visit', $parameters);
           $this->renderLayout();
       }
}

To dispatch an event, the Mage::dispatchEvent() function is used. In the indexAction( ) function, we will dispatch an event called helloworld_register_visit.

Fourth, we need a mechanism to see whether the event is dispatch or not. To test that the code works, we have to debug the Mage_Core_Model_App::dispatchEvent() function. In order to override this method that is magento core code, we need copy the app/code/core/Mage/Core/Model/App.php file to your local folder. Creating this folder structure as app\code\local\Mage\Core\Model and copy the App.php file into it. Then modify the dispatchEvent() function as shown below:

public function dispatchEvent($eventName, $args)
{
    foreach( $this->_events as $area => $events)  {
        if(!isset($events[$eventName])) {
            $eventConfig = $this->getConfig()->getEventConfig($area, $eventName);
            if(!$eventConfig) {
                $this->_events[$area][$eventName] = false;
                continue;
            }
            $observers = array();
             foreach( $eventConfig->observers->children() as $obsName => $obsConfig) {
            ............
        }
    }
}

Last, clear the cache and reload the page in the frontend and have a look at the var/log/system.log file. You are supposed to see some event names fired, inside there is an item named ‘helloworld_register_visit’ event.