Create Eventlist in Magento

Jul 08, 2013 Magento PHP

Events in magento are very cool. Mostly events make it possible to build very modular extensions for magento. In my first steps, I always searched for a full list of magento events. The problem with these lists were, they aren't complete and outdated. And you will never find dynamic events like this.

Mage::dispatchEvent($this->_eventPrefix.'_load_after', $this->_getEventData());

On that example, it's good to see, that the variable $_eventPrefix can be very important in your own extensions.

How to find a special Event?

In my example, I wanted to find an event for Lesti_Fpc. That should be the event, were I check if a page is in cache or not. I added the following line in app/Mage.php

public static function dispatchEvent($name, array $data = array())
{
    Mage::log($name . ' => ' . implode(', ', array_keys($data)), null, 'events.log'); /* <- add this line and DELETE it after testing */
    Varien_Profiler::start('DISPATCH EVENT:'.$name);
    $result = self::app()->dispatchEvent($name, $data);
    Varien_Profiler::stop('DISPATCH EVENT:'.$name);
    return $result;
}

Be sure, that Logging in Magento is enabled and run the action. In My case, I only visited the homepage of my shop. Please erase this line after the action. You should see a file events.log in /var/log directory. Here is just a little part this file.

2013-07-08T14:58:37+00:00 DEBUG (7): resource_get_tablename => resource, model_entity, table_name, table_suffix
2013-07-08T14:58:37+00:00 DEBUG (7): resource_get_tablename => resource, model_entity, table_name, table_suffix
2013-07-08T14:58:37+00:00 DEBUG (7): resource_get_tablename => resource, model_entity, table_name, table_suffix
2013-07-08T14:58:37+00:00 DEBUG (7): resource_get_tablename => resource, model_entity, table_name, table_suffix
2013-07-08T14:58:37+00:00 DEBUG (7): resource_get_tablename => resource, model_entity, table_name, table_suffix
2013-07-08T14:58:37+00:00 DEBUG (7): resource_get_tablename => resource, model_entity, table_name, table_suffix
2013-07-08T14:58:37+00:00 DEBUG (7): core_collection_abstract_load_before => collection
2013-07-08T14:58:37+00:00 DEBUG (7): core_collection_abstract_load_after => collection
2013-07-08T14:58:37+00:00 DEBUG (7): core_collection_abstract_load_before => collection
2013-07-08T14:58:37+00:00 DEBUG (7): core_collection_abstract_load_after => collection
2013-07-08T14:58:37+00:00 DEBUG (7): core_collection_abstract_load_before => collection
2013-07-08T14:58:37+00:00 DEBUG (7): core_collection_abstract_load_after => collection
2013-07-08T14:58:37+00:00 DEBUG (7): controller_front_init_before => front
2013-07-08T14:58:37+00:00 DEBUG (7): controller_front_init_routers => front
2013-07-08T14:58:37+00:00 DEBUG (7): resource_get_tablename => resource, model_entity, table_name, table_suffix
2013-07-08T14:58:37+00:00 DEBUG (7): resource_get_tablename => resource, model_entity, table_name, table_suffix
2013-07-08T14:58:37+00:00 DEBUG (7): model_load_after => object
2013-07-08T14:58:37+00:00 DEBUG (7): core_abstract_load_after => data_object, object
2013-07-08T14:58:37+00:00 DEBUG (7): resource_get_tablename => resource, model_entity, table_name, table_suffix
2013-07-08T14:58:37+00:00 DEBUG (7): core_locale_set_locale => locale
2013-07-08T14:58:37+00:00 DEBUG (7): resource_get_tablename => resource, model_entity, table_name, table_suffix
2013-07-08T14:58:37+00:00 DEBUG (7): controller_action_predispatch => controller_action
2013-07-08T14:58:37+00:00 DEBUG (7): customer_session_init => customer_session
2013-07-08T14:58:37+00:00 DEBUG (7): controller_action_predispatch_cms => controller_action
2013-07-08T14:58:37+00:00 DEBUG (7): controller_action_predispatch_cms_index_index => controller_action
2013-07-08T14:58:37+00:00 DEBUG (7): model_load_before => object, field, value
...

You can see every event, that was thrown in your action and every param of the event. Now can you listen to this event in your modul-path/etc/config.xml. Here a little part of app/code/community/Lesti/Fpc/etc/config.xml.

<?xml version="1.0"?>
<config>
    <!-- ... -->
    <global>
        <!-- ... -->
        <events>
            <!-- ... -->
            <controller_action_layout_generate_blocks_before>
                <observers>
                    <fpc_controller_action_layout_generate_blocks_before>
                        <class>fpc/observer</class>
                        <type>singleton</type>
                        <method>controllerActionLayoutGenerateBlocksBefore</method>
                    </fpc_controller_action_layout_generate_blocks_before>
                </observers>
            </controller_action_layout_generate_blocks_before>
            <!-- ... -->
       </events>
       <!-- ... -->
    </global>
    <!-- ... -->
</config>

Here is the part of app/code/community/Lesti/Fpc/Model/Observer.php. I just have to grab the objects of the event with the magic getter-function.

<?php
public function controllerActionLayoutGenerateBlocksBefore($observer)
{
    /* many funny things going on */
            $layout = $observer->getEvent()->getLayout();
    /* more funny things */
}

The first version of Lesti_Fpc had customer_session_init as anchor-event. Cause I needed the session for replacing the dynamic blocks. But I had to add custom-handles like customer_logged_in on my to the layout. And handles from other extensions never find a way into my layout. It's very uncommon, that other extenions should need there own handle just for dynamic blocks. To be very compatible to other extension, I did choose the controller_action_layout_generate_blocks_before as anchor of my extension. Now I have a complete layout of the current page. I just have to remove every blocks, that isn't dynamic and can generate my tiny layout.