Decorating a service

Overview

Decorating a service with your plugin is as simple as it is in Symfony. Make sure to have a look at the Symfony guide about decorating services.

Decorating a service

The main requirement here is to have a services.xml file loaded in your plugin. This can be achieved by placing the file into a Resources/config directory relative to your plugin's base class location. Make sure to also have a look at the method getServicesFilePath

From here on, everything works exactly like in Symfony itself.

Here's an example services.xml:

<?xml version="1.0" ?>

<container xmlns="http://symfony.com/schema/dic/services"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">

    <services>
        <service id="Swag\ServiceDecoration\Service\MyService" />

        <service id="Swag\ServiceDecoration\Service\ServiceDecorator" decorates="Swag\ServiceDecoration\Service\MyService">
            <argument type="service" id="Swag\ServiceDecoration\Service\ServiceDecorator.inner" />
        </service>
    </services>
</container>

And the related example services:

<?php declare(strict_types = 1);

namespace Swag\ServiceDecoration\Service;

class MyService implements MyServiceInterface
{
    public function doSomething(): string
    {
        return 'Did something.';
    }
}

<?php declare(strict_types=1);

namespace Swag\ServiceDecoration\Service;

class ServiceDecorator implements MyServiceInterface
{
    /**
     * The original service which could be used in the decorator
     *
     * @var MyServiceInterface
     */
    private $decoratedService;

    public function __construct(MyServiceInterface $myService)
    {
        $this->decoratedService = $myService;
    }

    public function doSomething(): string
    {
        $originalResult = $this->decoratedService->doSomething();

        return $originalResult . ' Did something additionally.';
    }
}

Note: It's highly recommended to work with interfaces when using the decoration pattern.

Source

There's a GitHub repository available, containing this example source. Check it out here.