Plugin Documentation

• Introduction
• Plugin Basics
• Plugin Types
  • 1. Before Plugin
  • 2. After Plugin
  • 3. Around Plugin
• Plugin Configuration
• Conclusion

Introduction

Plugins in Magento 2 provide a way to extend and modify the behavior of existing code without directly modifying it. This allows developers to customize Magento 2's functionality without the need for modifying core files, ensuring easier upgrades and compatibility with other extensions. In this documentation, we will explore the concept of plugins, their usage, and provide practical examples for better understanding.

Plugin Basics

A plugin, also known as an interceptor, is a class that modifies the behavior of a public method in a target class. It allows you to execute custom code before, after, or around the execution of the original method, without modifying the original code directly. This can be useful for adding new functionality, logging, caching, or modifying the input/output of a method.

Plugin Types

There are three types of plugins that can be used in Magento 2: before, after, and around. Let's discuss each type in more detail.

1. Before Plugin

A before plugin allows you to execute custom code before the execution of the target method. This is useful for intercepting the input parameters and modifying them if needed. For example, let's say we have a method doSomething($param1, $param2) in a class TargetClass. We can create a before plugin to intercept the execution of this method and modify the input parameters:

class BeforePlugin
{
    public function beforeDoSomething($subject, $param1, $param2)
    {
        // Modify $param1 and $param2 here
        $param1 = 'Modified ' . $param1;
        $param2 += 10;
 
        // You can also modify the subject instance itself if needed
        $subject->setSomeProperty('Modified Value');
 
        // Always return the modified parameters
        return [$param1, $param2];
    }
}

2. After Plugin

An after plugin allows you to execute custom code after the execution of the target method. This is useful for intercepting the return value of the method and modifying it if needed. For example, let's say we have a method doSomething() in a class TargetClass that returns a value. We can create an after plugin to intercept the execution of this method and modify the return value:

class AfterPlugin
{
    public function afterDoSomething($subject, $result)
    {
        // Modify $result here
        $result = 'Modified ' . $result;
 
        // Return the modified result
        return $result;
    }
}

3. Around Plugin

An around plugin allows you to execute custom code before and/or after the execution of the target method. This is useful when you want to completely override the original method's behavior or conditionally execute custom code. For example, let's say we have a method doSomething() in a class TargetClass. We can create an around plugin to intercept the execution of this method and modify its behavior:

class AroundPlugin
{
    public function aroundDoSomething($subject, $proceed)
    {
        // Code to execute before the original method
 
        // Call the original method using $proceed()
        $result = $proceed();
 
        // Code to execute after the original method
 
        // Modify $result if needed
 
        // Return the modified result
        return $result;
    }
}

Plugin Configuration

To use a plugin in Magento 2, you need to define its configuration in your module's di.xml file. Here's an example of how to configure a plugin for a class TargetClass:

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="TargetClass">
        <plugin name="before-plugin" type="Vendor\Module\Plugin\BeforePlugin" sortOrder="10" disabled="false"/>
        <plugin name="after-plugin" type="Vendor\Module\Plugin\AfterPlugin" sortOrder="20" disabled="false"/>
        <plugin name="around-plugin" type="Vendor\Module\Plugin\AroundPlugin" sortOrder="30" disabled="false"/>
    </type>
</config>

Make sure to replace TargetClass, Vendor\Module, and plugin names with your actual class and module names.

Conclusion

Plugins are a powerful tool in Magento 2 that allows you to modify the behavior of existing code without directly modifying it. By leveraging the before, after, and around plugin types, you can customize Magento's functionality to meet your specific requirements. Remember to configure your plugins in the di.xml file of your module. Happy plugin development!