Symfony 4.2 - How to decorate the UrlGenerator

Question

I want to decorate the Symfony UrlGenerator class.

Symfony\\Component\\Routing\\Generator\\UrlGenerator: ~

my.url_generator:
    class: AppBund         


        

Answer 1

I believe you have to decorate the Symfony\Component\Routing\Generator\UrlGeneratorInterface, because the services should depend on the interface and not on a specific implementation (class).

Answer 2

The right answer is : you shouldn't decorate UrlGeneratorInterface. You have to decorate 'router' service. Check here : https://github.com/symfony/symfony/issues/28663

** services.yml :

services:
    App\Services\MyRouter:
        decorates: 'router'
        arguments: ['@App\Services\MyRouter.inner']

** MyRouter.php :

<?php

namespace App\Services;

use Symfony\Component\Routing\RequestContext;
use Symfony\Component\Routing\RouterInterface;

class MyRouter implements RouterInterface
{
    /**
     * @var RouterInterface
     */
    private $router;

    /**
     * MyRouter constructor.
     * @param RouterInterface $router
     */
    public function __construct(RouterInterface $router)
    {
        $this->router = $router;
    }

    /**
     * @inheritdoc
     */
    public function generate($name, $parameters = [], $referenceType = self::ABSOLUTE_PATH)
    {
        // Your code here

        return $this->router->generate($name, $parameters, $referenceType);
    }

    /**
     * @inheritdoc
     */
    public function setContext(RequestContext $context)
    {
        $this->router->setContext($context);
    }

    /**
     * @inheritdoc
     */
    public function getContext()
    {
        return $this->router->getContext();
    }

    /**
     * @inheritdoc
     */
    public function getRouteCollection()
    {
        return $this->router->getRouteCollection();
    }

    /**
     * @inheritdoc
     */
    public function match($pathinfo)
    {
        return $this->router->match($pathinfo);
    }
}

Answer 3

I believe the issue is that UrlGenerator service name is Symfony\Component\Routing\Generator\UrlGeneratorInterface, and not Symfony\Component\Routing\Generator\UrlGenerator (cf. this code).

Secondly, when you decorate a service, the decorator will take the service name. So you should not need to modify router.options.generator_class.

Try with this configuration:

my.url_generator:
    class: AppBundle\Service\UrlGenerator
    decorates: Symfony\Component\Routing\Generator\UrlGeneratorInterface
    arguments: ['@my.url_generator.inner']

Setting public to false is likely not needed, as on Symfony4/Flex it should be the default value.

Update for comments: decorated service may look like this:

class MyUrlGenerator implements UrlGeneratorInterface
{
    private $originalUrlGenerator;

    public function __construct(UrlGeneratorInterface $innerUrlGenerator)
    {
        $this->originalUrlGenerator = $innerUrlGenerator;
    }

    public function generate($name, $parameters = [], $referenceType = self::ABSOLUTE_PATH)
    {
        // Maybe add your custom logic here... 
        // or completely override base method

        return $this->originalUrlGenerator->generate($name, $parameters, $referenceType);
    }
}