Symfony 6 parent controller to child controller dependency injection

Question

I have a base controller class that contains some utility methods that all child controllers use. Currently it has 3 dependencies, but there may be more in the future. So whenever I want to add a dependency to a child controller, I now have an issue where I think there are too many directives for dependency injection.

abstract class BaseController extends AbstractController
{
    public function __construct(
        protected readonly SerializerInterface $serializer,
        protected readonly ValidatorInterface $validator,
        private readonly ResponseGenerator $responseGenerator,
    ) {
    }
    ...

}

class ChildController extends BaseController
{
    // All parent class injections are required in all child classes.
    public function __construct(
        SerializerInterface $serializer,
        ValidatorInterface $validator,
        ResponseGenerator $responseGenerator,
        private readonly SomeRepository $someRepository,
        ...insert any other child controller-specific dependencies here.
    ) {
        parent::__construct($serializer, $validator, $responseGenerator);
    }
    ...
}

I tried using $this->container->get('serializer') in the base controller, but that didn't work because AbstractController: :$container is defined through injection, but has no constructor, so parent::__construct() cannot be called. Also, it doesn't give me a validator, so even if it works, it only solves part of the problem.

I tried looking for properties that I could use, like

abstract class BaseController extends AbstractController
{
    #[Inject]
    protected readonly SerializerInterface $serializer;

    #[Inject]
    protected readonly ValidatorInterface $validator;

But nothing similar was found (PHP-DI has it, but Symfony doesn't).

Is there a way to somehow eliminate duplicate dependencies in child controllers?

Answer 1

What you need is to be called a Service Subscriber

In Symfony, when controllers inherit AbstractController, they are service subscribers, which means they are injected with a library containing some common services (such as twig, serializers, form builders, etc. ) small container.

If you want some "common" services that your child controllers will use, you can extend the list by overriding getSubscribedServices() in the parent controller. Or if your controller does not inherit the default controller provided by Symfony, you just need to implement your own controller:

If your controller is a service (which I guess it already is), Symfony will use setter injection to inject the container into your controller.

The code will look like this:

<?php

use Symfony\Contracts\Service\ServiceSubscriberInterface;


class ParentController implement ServiceSubscriberInterface {
    protected ContainerInterface $container;
    public function setContainer(ContainerInterface) { $this->container = $container; } 

    public static function getSubscribedServices() {
         // 这是静态的，所以Symfony可以在不实例化控制器的情况下“看到”所需的服务。
         // 在这里定义一些常见的服务，一个示例在Symfony的AbstractController中
    }
}

class ChildController extends ParentController {
    // 使用自定义DI来为子控制器提供服务。

    public function indexAction {
        // 你可以使用$this->container->get(...)来获取服务
    }

}