4.2: The Container is not clear

[chiqui3d]

Hello,
I started using the stable version of Symfony 4.2, but it's not clear to me how to use $this->container, since all the documentation of 4.2 used it, but I haven't really been able to use it.

Example:

//services.yml
    app.theme:
        class: App\Service\Theme
        public: true
        autowire: true

Error:

Service "app.theme" not found: even though it exists in the app's container, the container inside "App\Controller\Front\BlogController" is a smaller service locator that only knows about the "doctrine", "form.factory", "http_kernel", "parameter_bag", "request_stack", "router", "security.authorization_checker", "security.csrf.token_manager", "security.token_storage", "serializer", "session", "templating" and "twig" services.Try using dependency injection instead.

That combination together with many other combinations, has not worked for me, so not being what happens in the Container, I have followed everything from documentation, but there are many more that refer to the Container, but not if your intention is to remove it completely.

So, my question is if I can make use of the container or what is really happening, please hope you can help me understand.

Reference:
https://symfony.com/doc/current/service_container.html#public-versus-private-services
https://symfony.com/doc/master/service_container/alias_private.html#aliasing
https://symfony.com/doc/master/service_container/autowiring.html#an-autowiring-example
https://symfony.com/doc/current/service_container/calls.html

Well, almost everything related to the container is not clear.

[tomtomau]

Hi there!

It's generally not recommend to inject the entire Container and instead inject each dependency you require.

I'm assuming the issue you're facing is that you are working with the Container from AbstractController.

As per the docs, the Container autoconfigured for you in AbstractController has a limited scope and only has certain services injected into it:

public function new()
{
    // ...

    // this ONLY works if you extend the base Controller
    $adminEmail = $this->container->getParameter('admin_email');

    // or a shorter way!
    // $adminEmail = $this->getParameter('admin_email');
}

If your controller extends \Symfony\Bundle\FrameworkBundle\Controller\Controller rather than \Symfony\Bundle\FrameworkBundle\Controller\AbstractController then you should be ok.

I would however strongly recommend that you inject your service into the constructor (or method) instead. If you're coming from earlier versions of Symfony, you might be accustomed to manually registering your service and pulling it from the container manually in your controller method.

These days, the default configuration of Symfony is to autoconfigure and autowire, so you should be able to simply:

class BlogController extends AbstractController
{
    public function myMethod(Theme $theme): Response
    {
        // The framework will autoinject Theme for us
        $theme->callSomeMethod();
    }
}

[chiqui3d]

Hello @tomtomau ,

First of all, thank you for taking the time to answer.

Yes exactly I use AbstractController and when installing version 4.2 I have no choice because Controller was deprecated like with Auto-Injection, then I understand that the best way is to do it by the Constructor and that's as I'm doing it. But I'm doing tests to know the options I have on the Container and nothing works for me when I look at the documentation of the Service Container, so the documentation should be much clearer, there are about 20 documents that talk about the Service Container, but it's not really clear, you really have to predict or guess where Symfony wants to drive me, it's true that I'm not an expert and I may be making a mess, but that has to be clearer, and really that could be summarized in two documents not in 20 as it has now, because I'm surfing in the documentation the Container without having a clear idea.

Note:

Get the extend container with:

    public static function getSubscribedServices()
    {
        return array_merge(parent::getSubscribedServices(), [
            'app.configuration' => Configuration::class,
            'app.theme'         => Theme::class
        ]);

    }

and I guess with ContainerBuilder I can do it too.

Thanks :)

[laurentiu1981]

Here's what I did, for symfony 4.2, considering that I wanted a service with some configurable arguments.

in services.yaml:

services:
    ....

    my.service:
        class: Your\Service\ClassName
        arguments:
        - arg: '%env(config_arg)%'
          second_arg: '%env(config_second_arg)%'

    Your\Service\ClassName: '@my.service'

In a controller:

use Your\Service\ClassName;

class MyController extends AbstractController {
  public function myAction(ClassName $service) { 
     ...
  }
}

[ahmetelcik]

if we using dynamic services? what can i do?

modules services example:

[xabbuh]

For support, please refer to one of the support channels. Thank you for understanding.

[tobalsan]

Hey @ahmetelcik

I had the exact same issue, and found a simple solution. You just have to use Symfony's service locator.