module.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
    <module name="Training_Sales">
        <sequence>
            <module name="Magento_Sales"/>
        </sequence>
    </module>
</config>

registration.php

<?php

use Magento\Framework\Component\ComponentRegistrar;

ComponentRegistrar::register(
    ComponentRegistrar::MODULE,
    'Training_Sales',
    __DIR__);

Add a plugin and provide some functionality

The next step is to add some functionality to our basic module. A Plugin is an essential tool that all Adobe Commerce developers use. This video and tutorial help you create a plugin.

Things to remember for Plugins

  • All plugins are declared in di.xml.
  • The plugin requires a unique name
  • disabled and sortOrder are optional
  • Scope of the plugin is set by the folder that it is inside
  • Plugins can be executed before, after or both (around) the method is called
  • Avoid using around plugins. They are tempting to use but often are the wrong choice and will lead to performance issues.

Plugin code samples

Here are the XML and PHP classes used in the tutorial for adding a plugin to the first module

app/code/Training/Sales/etc/adminhtml/di.xml

<?xml version="1.0" ?>
<!--
/**
 * Copyright &copy; Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <!-- A Plugin that executes when the admin user places an order -->
    <type name="Magento\Sales\Model\Order">
        <plugin name="admin-training-sales-add-logging" type="Training\Sales\Plugin\AdminAddLoggingAfterOrderPlacePlugin" disabled="false" sortOrder="0"/>
    </type>
</config>

app/code/Training/Sales/etc/frontend/di.xml

<?xml version="1.0" ?>
<!--
/**
 * Copyright &copy; Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <!-- A plugin that executes when a customer uses the LoginPost controller from the Luma frontend -->
    <type name="Magento\Customer\Controller\Account\LoginPost">
        <plugin name="training-customer-loginpost-plugin"
                type="Training\Sales\Plugin\CustomerLoginPostPlugin" sortOrder="20"/>
    </type>
</config>

app/code/Training/Sales/etc/webapi_rest/di.xml

<?xml version="1.0" ?>
<!--
/**
 * Copyright &copy; Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <!-- A plugin that executes when the REST API is used OR when the Luma frontend places an order -->
    <type name="Magento\Sales\Model\Order">
        <plugin name="rest-training-sales-add-logging" type="Training\Sales\Plugin\RestAddLoggingAfterOrderPlacePlugin"/>
    </type>
</config>

app/code/Training/Sales/Plugin/AdminAddLoggingAfterOrderPlacePlugin.php

<?php

declare(strict_types=1);

namespace Training\Sales\Plugin;

use Magento\Sales\Model\Order;
use Psr\Log\LoggerInterface;

/**
 *
 */
class AdminAddLoggingAfterOrderPlacePlugin
{

    /**
     * @var LoggerInterface
     */
    private LoggerInterface $logger;

    /**
     * @param LoggerInterface $logger
     */
    public function __construct(
        LoggerInterface $logger
    ) {
        $this->logger = $logger;
    }

    /**
     * Add log after an order is placed
     *
     * @param Order $subject
     * @param Order $result
     * @return Order
     */
    public function afterPlace(Order $subject, Order $result): Order
    {
        // Log this admin area order
        $this->logger->notice('An ADMIN User placed an Order - $' . $subject->getBaseTotalDue());
        return $result;
    }
}

app/code/Training/Sales/Plugin/CustomerLoginPostPlugin.php

<?php

declare(strict_types=1);

namespace Training\Sales\Plugin;

use Psr\Log\LoggerInterface;
use Magento\Framework\App\RequestInterface;

/**
 * Introduces Context information for ActionInterface of Customer Action
 */
class CustomerLoginPostPlugin
{

    /**
     * @var LoggerInterface
     */
    private LoggerInterface $logger;

    /**
     * @var RequestInterface
     */
    private RequestInterface $request;

    /**
     * @param LoggerInterface $logger
     * @param RequestInterface $request
     */
    public function __construct(LoggerInterface $logger, RequestInterface $request)
    {
        $this->logger = $logger;
        $this->request = $request;
    }

    /**
     * Simple example of a before Plugin on a public method in a Controller
     */
    public function beforeExecute()
    {
        $login = $this->request->getParam('login');
        $username = $login['username'];
        $this->logger->notice( "Login Post controller was used for " . $username );
    }
}

app/code/Training/Sales/Plugin/RestAddLoggingAfterOrderPlacePlugin.php

<?php

declare(strict_types=1);

namespace Training\Sales\Plugin;

use Magento\Sales\Model\Order;
use Psr\Log\LoggerInterface;

/**
 *
 */
class RestAddLoggingAfterOrderPlacePlugin
{

    /**
     * @var LoggerInterface
     */
    private LoggerInterface $logger;

    /**
     * @param LoggerInterface $logger
     */
    public function __construct(
        LoggerInterface $logger
    ) {
        $this->logger = $logger;
    }

    /**
     * Add log after an order is placed
     *
     * @param Order $subject
     * @param Order $result
     * @return Order
     */
    public function afterPlace(Order $subject, Order $result): Order
    {
        // Log this customer driven order
        $this->logger->notice('A Customer placed an Order for $' . $subject->getBaseTotalDue());
        return $result;
    }
}

Useful resources

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