Plugins Deep Dive — Before, After, and Around Methods

Plugin Declaration

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="Magento\Catalog\Model\Product">
        <plugin name="vendor_product_plugin"
                type="Vendor\Module\Plugin\ProductPlugin"
                sortOrder="10"/>
    </type>
</config>

Before Plugin

Runs before the original method. Can modify arguments:

namespace Vendor\Module\Plugin;

class ProductPlugin
{
    public function beforeSetName(
        \Magento\Catalog\Model\Product $subject,
        string $name
    ): string {
        return strtoupper($name);
    }
}

After Plugin

Runs after the original method. Can modify the return value:

public function afterGetName(
    \Magento\Catalog\Model\Product $subject,
    string $result
): string {
    return $result . ' (Modified)';
}

Around Plugin

Wraps the original method. Has full control:

public function aroundGetName(
    \Magento\Catalog\Model\Product $subject,
    callable $proceed
): string {
    $startTime = microtime(true);
    $result = $proceed();
    $elapsed = microtime(true) - $startTime;
    $this->logger->info('getName took: ' . $elapsed);
    return $result;
}

If $proceed() is not called, the original method is skipped.

Generated Interceptor Class

When you create a plugin, Magento generates an interceptor class:

// Generated: var/classes/Vendor/Module/Plugin/ProductPluginInterceptor.php
namespace Vendor\Module\Plugin;

class ProductPluginInterceptor
{
    public function aroundGetName(
        \Magento\Catalog\Model\Product $subject,
        callable $proceed
    ): string {
        // Plugin logic here
        $result = $proceed();
        return $result;
    }
}

How Interception Works

1. DI generates interceptor classes for target classes with plugins
2. ObjectManager returns the interceptor instead of the original class
3. Each method is wrapped with plugin calls
4. Execution order: before plugins -> original method -> after plugins

// ObjectManager returns interceptor
$product = $objectManager->get(\Magento\Catalog\Model\Product::class);
// $product is actually ProductInterceptor, not Product

Plugin Chain Execution

beforePlugin1 -> beforePlugin2 -> OriginalMethod -> afterPlugin2 -> afterPlugin1

Around plugins wrap the entire chain:

aroundPlugin1 -> { beforePlugin2 -> OriginalMethod -> afterPlugin2 } -> afterPlugin1

Regenerating Interceptors

After adding or removing plugins, regenerate:

php bin/magento setup:di:compile
php bin/magento cache:clean

Cannot Plugin Non-Public Methods

Plugins only work on public methods:

// This will NOT work
<type name="Vendor\Module\Model\Product">
    <plugin name="plugin" type="Vendor\Module\Plugin\Plugin"/>
</type>

// Target class
public class Product {
    protected function validate() { /* ... */ }  // Cannot plugin this
    public function save() { /* ... */ }          // Can plugin this
}

Cannot Plugin Final Classes or Methods

final class Product {
    public function save() { /* ... */ }  // Cannot plugin
}

// Also cannot plugin if method is final
public final function save() { /* ... */ }

Cannot Plugin Static Methods

public static function factory() { /* ... */ }  // Cannot plugin

Cannot Plugin Methods Called via self::

class Product {
    public function save() {
        $this->validate();  // Can plugin this
        self::doSave();     // Cannot plugin self:: calls
        static::doSave();   // Can plugin this (late static binding)
    }
}

Cannot Plugin Constructor

Constructors are never intercepted by plugins.

Performance Impact

Each plugin adds overhead. Profiling shows:

• Before plugin: ~0.1ms per call
• After plugin: ~0.1ms per call
• Around plugin: ~0.15ms per call

Heavy plugins on high-traffic methods accumulate overhead.

Interceptor Files Location

Generated interceptor classes are in:

var/classes/Vendor/Module/Plugin/ClassNameInterceptor.php

Analyzing Generated Code

// View generated interceptor
$file = BP . '/var/classes/Vendor/Module/Plugin/ProductInterceptor.php';
echo file_get_contents($file);

Plugin Configuration Methods

<type name="Magento\Catalog\Model\Product">
    <plugin name="my_plugin"
            type="Vendor\Module\Plugin\ProductPlugin"
            sortOrder="10"
            disabled="false"/>
</type>

Disabling Plugins

<type name="Magento\Catalog\Model\Product">
    <plugin name="third_party_plugin" disabled="true"/>
</type>

Plugin on Interface

<!-- Plugin on interface applies to all implementations -->
<type name="Magento\Catalog\Api\ProductRepositoryInterface">
    <plugin name="repo_plugin" type="Vendor\Module\Plugin\RepoPlugin"/>
</type>

This intercepts all classes implementing ProductRepositoryInterface.