Configuring Specific (Named) Arguments

Hi Ryan,

I was wondering if there are any differences using this:

AppBundle\Service\MarkdownTransformer:
    $cacheDriver: '@doctrine_cache.providers.my_markdown_cache'

instead of this:

AppBundle\Service\MarkdownTransformer:
    arguments:
        $cacheDriver: '@doctrine_cache.providers.my_markdown_cache'

since it looks like both works.

Yo Bruno Lima!

Wow, nice find! They're both identical actually! But in all of the 3.3 changes, I didn't even know this was one of them! So yea, use whichever you want. The shorter syntax is pretty cool looking :). The only downside is if you ever need to add more config (like tags), you'll then need to put the arguments under an arguments key. But, that's not too common.

Cheers!

Great! Thank you.

Hi Ryan,

I got stucked somewhere when i was trying to do the same in my own code.
In my Container Class I'm passing two services as u can see,

 public function __construct(TwitterClient $transformerDriver,Rot13Transformer $status).

When i'm trying to pass the arguments inside it it throwing an error:

The service "AppBundle\Services\ServiceContainer" has a dependency on a non-existent service "AppBundle\Services\ServiceContainer".

YML CONFIG:

 AppBundle\Services\ServiceContainer:
    arguments:
        $transformerDriver: '@AppBundle\Services\ServiceContainer'

And when i'M trying to give service name in this format:

AppBundle\Services\ServiceContainer:
       arguments: ['@twitter_events_service', '@string_events_service']

Error: The service "AppBundle\Services\ServiceContainer" has a dependency on a non-existent service "twitter_events_service".

As u told first search the container and then use that value as a argument:-but when i do debug:container i am unable to find the service.

So i went to appDevContainer:- Here they are using something like this:-

return $this->services['AppBundle\Services\ServiceContainer'] = new \AppBundle\Services\ServiceContainer(new \AppBundle\Services\TwitterClient(), new \AppBundle\Test\Rot13Transformer());

But when i get into your project appDevCotainer File :- they are using services in this format:

return $this->services['app.markdown_transformer'] = new \AppBundle\Service\MarkdownTransformer($this->get('markdown.parser'));

And one more thing if i remove all the config from services.yml its working fine. ??

Hey Vivek Sharma

You have a subtle error, look at the service you are injecting to ServiceContainer

 AppBundle\Services\ServiceContainer:
    arguments:
        $transformerDriver: '@AppBundle\Services\ServiceContainer'

You are saying that $transformerDriver is an instance of ServiceContainer, but `$transformerDriver is a property of ServiceContainer

When you remove everything, I think it is working because you have type-hinted your arguments, so autowire + autoconfigure can do all the work

Have a nice day

Hi Ryan,

In my services.yml, '@service_container' is marked with a warnng in PhpStorm. The warning is "expect instance of: Symfony\Component\DependancyInjection\Container Provided instance of service id does not match"
Is this warning related to the autowiring? How do you fix it? Thanks.

Hey Scott,

Hm, what typehint do you have for this argument in your service? I wonder about FQCN of this class. Looks like you misprint namespace, it should be "Symfony\Component\DependencyInjection\Container", or probably better use interface instead "Symfony\Component\DependencyInjection\ContainerInterface", notice "Dependency" not "Dependancy".

Cheers!

Sorry, <em>"Dependancy"</em> was a typo. Here is the class:

namespace AppBundle\Service;

use Doctrine\ORM\EntityManager;
use GuzzleHttp\Client;
use GuzzleHttp\Exception\ClientException;
use Symfony\Component\DependencyInjection\Container;
use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;

class Utils
{
  /** @var EntityManager */
  private $em;
  /** @var Container */
  private $container;

  function __construct(EntityManager $em, Container $container)
  {
    $this->em = $em;
    $this->container = $container;
  }

Here is the entry in services.yml:

  AppBundle\Service\Utils:
    arguments: [ '@doctrine.orm.entity_manager', '@service_container' ]

Hey Scott,

Hm, looks correct, so you can just ignore it :) I think it can be a bug in PhpStorm inspection. Well, I did a bit of debugging:
bin/console debug:container | grep service_container

And I see that "service_container" service points to Symfony\Component\DependencyInjection\ContainerInterface, so try to use the interface instead in __construct():

// ...
use Symfony\Component\DependencyInjection\ContainerInterface;
// ...

class Utils
{
  public function __construct(EntityManager $em, ContainerInterface $container)
  {
    // ...
  }
}

Probably it will fix the warning. Actually, better always use interfaces if possible for type-hints.

Cheers!

Wow, that worked! Thank you very much.
For my education, why do you think it is better to use interfaces instead of the actual class?

Hey Scott,

Because interfaces gives you more flexibility! If you use an interface for a type-hint - you can pass *any* object which implements this interface. But if you type-hint with a real object - you are allowed to pass only this object, or any object which extends this object. Actually, it's not too important, but you would see the difference if you have a few classes which implements the same interfaces. For example, let's say we have CacheInterface and a few classes which implements this interface like RedisCache and LocalCache. If you type-hint with CacheInterface - you can easily switch your cache provider and even don't need to change the type-hint.

If you wonder more about the difference between Classes, Abstract classes, Interfaces, Traits, etc. and their use cases - take a look at our https://knpuniversity.com/s... course.

Cheers!