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[DependencyInjection] Target parameter attribute does not work for Services #51565

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issamkhadiri1989 opened this issue Sep 5, 2023 · 6 comments
Closed

[DependencyInjection] Target parameter attribute does not work for Services #51565

issamkhadiri1989 opened this issue Sep 5, 2023 · 6 comments
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Bug DependencyInjection Status: Needs Review

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@issamkhadiri1989
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Symfony version(s) affected

6.3

Description

Hello,

I am having an issue with the #[Target] attribute when using it in services.

According to https://symfony.com/doc/current/service_container/autowiring.html#dealing-with-multiple-implementations-of-the-same-type,

when I have 2 services implementing the same interface i have 2 choices:

  • create an alias from the Interface and use a default service and create a named alias for the other services

  • use the Target attribute.

With the first choice, everything works fine. But with the 2nd choice, I have created a default alias from the interface, then I create another alias to the other service. When I use the alias in some service I got an error

Cannot resolve argument $client of "App\Controller\TwitterController::index()": Cannot autowire service "App\Service\TwitterClient": "#[Target('appTransformerUpper')" on argument "$transformer" of method "__construct()"

Am I doing something wrong ?

How to reproduce

  1. Create an interface
interface TransformerInterface
{
    public function transform(string $input): string;
}
  1. Create 2 services that implement the same interface
class UppercaseTransformer implements TransformerInterface
{
    public function transform(string $input): string
    {
        return \strtoupper($input);
    }
}

class Rot13Transformer implements TransformerInterface
{
    public function transform(string $input): string
    {
        return \str_rot13($input);
    }
}
  1. Create an alias from the interface in services.yaml
App\Utils\TransformerInterface: '@App\Utils\Transformer\Rot13Transformer'

And then, create another alias to the other service (cf the doc)

app.transformer.upper: '@App\Utils\Transformer\UppercaseTransformer'

Use the Interface as a Type-hint in some service (eg. TwitterClient service) like the following

use Symfony\Component\DependencyInjection\Attribute\Target;

class TwitterClient
{
    private TransformerInterface $transformer;

    public function __construct(
        #[Target('app.transformer.upper')]
        TransformerInterface $transformer
    ) {
        $this->transformer = $transformer;
    }
 ...
}

Possible Solution

No response

Additional Context

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@HypeMC
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HypeMC commented Sep 5, 2023

The #[Target] attribute doesn't work with service aliases, use the #[Autowire] attribute instead. See #50541.

@xabbuh
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xabbuh commented Sep 6, 2023

closing as explained

@xabbuh xabbuh closed this as not planned Won't fix, can't repro, duplicate, stale Sep 6, 2023
@issamkhadiri1989
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Thank you @HypeMC

It works !

I added a App\Utils\TransformerInterface $upperTransformer: '@App\Utils\Transformer\UppercaseTransformer' and then used #[Target('upperTransformer')].

However I should mention that in the doc, the statement

Another possibility is to use the #[Target] attribute. By using this attribute on the argument you want to autowire, you can define exactly which service to inject by using its alias.

could be confusing as there is no example explaining the idea.

Thank you again for the explanation

Best regards !

@stof
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stof commented Sep 6, 2023

the Target attribute works with named aliases, allowing to keep the argument name itself whather you want (so not always matching your named alias)

@eerison
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eerison commented Sep 29, 2023

Thank you @HypeMC

It works !

I added a App\Utils\TransformerInterface $upperTransformer: '@App\Utils\Transformer\UppercaseTransformer' and then used #[Target('upperTransformer')].

However I should mention that in the doc, the statement

Another possibility is to use the #[Target] attribute. By using this attribute on the argument you want to autowire, you can define exactly which service to inject by using its alias.

could be confusing as there is no example explaining the idea.

Thank you again for the explanation

Best regards !

did you add this in your bind configs?

I do not know why the servers are not found in binds :/

@issamkhadiri1989
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Hi @eerison

No i didn't have to add any bind config. You need to have a named alias and then you can report the name as Target's argument

@HypeMC HypeMC mentioned this issue Apr 14, 2024
Merged
javiereguiluz added a commit to symfony/symfony-docs that referenced this issue Jun 24, 2024
@javiereguiluz
minor #19789 [DependencyInjection] Clarify the #[Target] attribute …
59d5b18 
…(HypeMC)

This PR was merged into the 5.4 branch.

Discussion
----------

[DependencyInjection] Clarify the `#[Target]` attribute

The `#[Target]` attribute seems to be a constant source of confusion for developers, as evident by:

- symfony/symfony#50541
- symfony/symfony#51565
- symfony/symfony#54578

Also, the example given is either unclear or just wrong. Hopefully, this helps clarify things.

Commits
-------

2fb1ada [DependencyInjection] Clarify the `#[Target]` attribute
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@stof @xabbuh @HypeMC @eerison @carsonbot @issamkhadiri1989