events_xml.md

events.xml Reference Documentation

[TOC]

The events.xml file in Magento 2 is crucial for creating and handling events within the system. This file is responsible for defining the events and the observers which listen to these events.

Overview

Magento 2's events.xml is typically located under the etc directory in a module. The directory structure is as follows:

app
└── code
    └── Vendor
        └── Module
            └── etc
                ├── events.xml
                └── ...

File Structure

The events.xml file uses XML format and generally follows this structure:

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="event_name">
        <observer name="observer_name" instance="Vendor\Module\Observer\ObserverClass" method="execute"/>
    </event>
</config>

• event_name refers to the event's unique name, which will be dispatched by Magento.
• observer_name is the unique name of the observer in the context of this event.
• Vendor\Module\Observer\ObserverClass is the class responsible for handling the event when it's triggered.
• method is the method in the ObserverClass that will be called.

Defining an Event

Defining an event in the events.xml file is as simple as adding an event tag with a unique name attribute. Here's an example:

<event name="catalog_product_save_after">
    <observer name="catalog_product_save_after_observer" instance="Vendor\Module\Observer\ProductSaveAfter"
              method="execute"/>
</event>

In this case, the catalog_product_save_after event is defined, which will trigger after a product is saved.

Defining an Observer

Defining an observer for the event involves adding an observer tag inside the event tag. The instance attribute specifies the class that will handle this event, while the method attribute defines the method that will be called.

<observer name="catalog_product_save_after_observer" instance="Vendor\Module\Observer\ProductSaveAfter"
          method="execute"/>

Here, when the catalog_product_save_after event triggers, the execute method of the Vendor\Module\Observer\ProductSaveAfter class will be called.

Observer Class

An observer class typically extends Magento\Framework\Event\ObserverInterface and implements the execute method, where the event logic resides.

Here's a sample observer class:

<?php

namespace Vendor\Module\Observer;

use Magento\Framework\Event\ObserverInterface;
use Magento\Framework\Event\Observer;

class ProductSaveAfter implements ObserverInterface
{
    public function execute(Observer $observer)
    {
        $product = $observer->getEvent()->getProduct();
        // Handle the event logic here
    }
}

Conclusion

The events.xml file plays a crucial role in Magento 2's event-driven programming paradigm. It facilitates interaction between modules and helps maintain code decoupling, making it easier to modify or extend the functionalities. By mastering event and observer implementation in Magento 2, developers can build highly flexible and scalable ecommerce solutions.