Chapters

11 Chapters | 45:42 |

01

Introducción

6:27
02

Patrón de comandos con AutowireLocator

6:27
03

Simplificar con AutoconfigureTag y AsTaggedItem

2:50
04

Lista de botones con AutowireIterator

4:44
05

Contenedor e Iterador con ServiceCollectionInterface

3:46
06

Asignar un alias a una interfaz con AsAlias

5:10
07

Decorar un servicio con AsDecorator

1:54
08

Imponer el autocableado por nombre con Target

3:56
09

Habilitar Servicios en Entornos Específicos con Cuando

2:31
10

Servicios perezosos

4:00
11

Más atributos de pereza

3:57

> Symfony 7 > Inyección de dependencias #[Attributes]

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07.

Decorar un servicio con AsDecorator

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En el capítulo anterior, utilizamos #[AsAlias] para asignar un alias de RemoteInterface aButtonRemote, de modo que cuando tecleamos RemoteInterface, nos da el servicioButtonRemote. Pero, ¡esto rompió nuestro registro! Tenemos que decirle a Symfony que nos dé LoggerRemote en su lugar, pero que pase el servicio ButtonRemote aLoggerRemote.

`#[AsDecorator]`

Básicamente, tenemos que decirle a Symfony que ButtonRemote está siendo decorado por LoggerRemote. Para ello, en LoggerRemote, utiliza otro atributo: #[AsDecorator] pasando el servicio que decora: ButtonRemote::class:

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                        38 lines
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            src/Remote/LoggerRemote.php
        
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                                                    // ... lines 1 - 5
                            
            use Symfony\Component\DependencyInjection\Attribute\AsDecorator;
        
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                                                    // ... line 7
                            
            #[AsDecorator(ButtonRemote::class)]
        
            final class LoggerRemote implements RemoteInterface
        
                Show Lines

                                                    // ... lines 10 - 38

Esto le dice a Symfony:

Oye, si algo te pide el servicio ButtonRemote, dale LoggerRemote en su lugar.

En esencia, Symfony intercambia los servicios y convierte ButtonRemote en el servicio "interno" de LoggerRemote. Esto solidifica la necesidad del RemoteInterface que creamos antes. Si intentáramos inyectar directamente ButtonRemote, obtendríamos un error de tipo porque Symfony estaría intentando inyectar LoggerRemote.

Decoración del servicio

Así que, sígueme en esto: autoconectamos RemoteInterface. Eso está aliasado a ButtonRemote, así que Symfony intenta darnos eso. Pero entonces, gracias a #[AsDecorator], lo cambia por LoggerRemote... pero pasa ButtonRemote a LoggerRemote. En resumen, AsDecorator nos permite decorar un servicio existente con otro.

Vuelve a la aplicación, actualízala y... pulsa "subir volumen". Comprueba el panel del perfilador "Registros" y... ¡estamos registrando de nuevo!

Decoradores múltiples

Utilizar #[AsDecorator] hace que sea superfácil añadir múltiples decoradores. Quizá queramos añadir un decorador de limitación de velocidad para evitar que los niños machaquen botones. Sólo tendríamos que crear una clase RateLimitingRemote que implemente RemoteInterface y añadir#[AsDecorator(ButtonRemote::class)].

#[AsDecorator(ButtonRemote::class)]
class RateLimitingRemote implements RemoteInterface
{
    public function __construct(
        private RateLimiter $rateLimiter,
        private RemoteInterface $inner,
    ) {
    }

    // ...
}

A continuación: Añadiremos un canal de registro personalizado y exploraremos el "autocableado con nombre"

9 Comments

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RobC25 8 months ago edited

Hi everyone,

First thanks for your great course !

I'm trying to implement another decorator class (RateLimiterButton) in addition to LoggerRemote (with priority 5):

#[AsDecorator(ButtonRemote::class, priority: 10)]
class RateLimiterRemote implements RemoteInterface
{
    public function __construct(
        private readonly RateLimiterFactory $remoteButtonLimiter,
        private readonly ButtonRemote $inner
    )
    {}

but i'm facing a Circular reference error:

Circular reference detected for service "App\Remote\LoggerRemote", path: "App\Remote\LoggerRemote -> App\Remote\LoggerRemote".

I'm i missing something ?

Thanks

| Reply |

kbond SFCASTS RobC25 8 months ago edited

Hey @RobC25!

Small thing, instead of:

private readonly ButtonRemote $inner

Inject the interface instead:

private readonly RemoteInterface $inner

ButtonRemote refers to the fully decorated service, in this case RateLimiterRemote so Symfony is trying to inject it into itself. When using RemoteInterface, Symfony is smart enough to inject the service it's decorating.

Hope that helps!
--Kevin

| Reply |

RobC25 kbond 8 months ago

Thanks a lot, it's more clear now.

| Reply |

Amine 10 months ago HIGHLIGHTED

Hi All,

Thank you

I would add it's possible to add decorateor like that
#[AsDecorator(RemoteInterface::class)]

| Reply |

kbond SFCASTS Amine 10 months ago edited

Hey @Amine!

You're absolutely right. I should have done that!

-Kevin

| Reply |

KamilS 1 year ago

Hi there,

One thing is confusing to me here. In the previous chapter we said that we use #[AsAlias] to tell Symfony which of our two services to use when we type-hint RemoteInterface. This was done while injecting RemoteInterface into LoggerRemote. That's clear.

Now, we mark LoggerRemote with #[AsDecorator], so anything asks for the ButtonRemote service, give them LoggerRemote instead.

So why doesn't it loop in LoggerRemote? There we inject RemoteInterface, and via #[AsAlias] we expect and get ButtonRemote, but via #[AsDecorator] Symfony should try to inject LoggerRemote instead. Service self injection?

| Reply |

kbond SFCASTS KamilS 1 year ago edited

Hey @KamilS!

Yeah, this part can be a bit tough to conceptualize. Let's see if I can explain it a different way:

In the last chapter, when we added #[AsAlias] to ButtonRemote, this told Symfony to inject ButtonRemote whenever we autowire RemoteInterface.

Now, when we add #[AsDecorator(ButtonRemote::class)] to LoggerRemote, Symfony, behind the scenes, swaps the RemoteInterface alias to now point to LoggerRemote.

If we added a new service: RateLimiterRemote with #[AsDecorator(ButtonRemote::class)], Symfony would again swap the alias so that RemoteInterface points to RateLimiterRemote. It always swaps it to the top-level of the decoration stack.

I hope that helps but let me know if it's still confusing.

--Kevin

| Reply |

KamilS kbond 1 year ago edited

Thanks @kbond!

But the question is: Why is LoggerRemote still injected with ButtonRemote and not LoggerRemote which is its decorator (or in the future with RateLimiterRemote)? Is it because it is the same class definition and at this stage Symfony does not know about decorating yet, and the current service implementing RemoteInterface is still ButtonRemote?

final class LoggerRemote implements RemoteInterface
{
    public function __construct(
        private LoggerInterface $logger,
        private RemoteInterface $inner, // here, why ButtonRemote, and not LoggerRemote (or RateLimiterRemote in the future)?
    ) {
    }
    ...
}

| Reply |

kbond SFCASTS KamilS 1 year ago

here, why ButtonRemote, and not LoggerRemote

Because LoggerRemote has the AsDecorator(ButtonRemote::class) attribute, this changes how the LoggerRemote is wired up. For $inner, a new service is created internally (LoggerRemote.inner), and this is injected for $inner. This new service is the real ButtonRemote. Additionally, the decorator logic changes the RemoteInterface alias to point to LoggerRemote instead of ButtonRemote.

It might help to use bin/console debug:container remote to see these services.

I hope this helps but if not, please let me know and I can try and explain differently!

| Reply |

Symfony 7.1

What PHP libraries does this tutorial use?

// composer.json
{
    "require": {
        "php": ">=8.2",
        "ext-ctype": "*",
        "ext-iconv": "*",
        "symfony/console": "7.1.*", // v7.1.3
        "symfony/dotenv": "7.1.*", // v7.1.3
        "symfony/flex": "^2", // v2.4.6
        "symfony/framework-bundle": "7.1.*", // v7.1.3
        "symfony/mailer": "7.1.*", // v7.1.5
        "symfony/monolog-bundle": "^3.0", // v3.10.0
        "symfony/runtime": "7.1.*", // v7.1.1
        "symfony/string": "7.1.*", // v7.1.3
        "symfony/twig-bundle": "7.1.*", // v7.1.1
        "symfony/ux-icons": "^2.18", // v2.19.0
        "symfony/ux-twig-component": "^2.18", // v2.19.0
        "symfony/yaml": "7.1.*", // v7.1.1
        "twig/extra-bundle": "^2.12|^3.0", // v3.11.0
        "twig/string-extra": "^3.10", // v3.11.0
        "twig/twig": "^2.12|^3.0" // v3.11.0
    },
    "require-dev": {
        "symfony/debug-bundle": "7.1.*", // v7.1.1
        "symfony/stopwatch": "7.1.*", // v7.1.1
        "symfony/web-profiler-bundle": "7.1.*" // v7.1.3
    }
}

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What PHP libraries does this tutorial use?

Show Lines	// ... lines 1 - 5
	use Symfony\Component\DependencyInjection\Attribute\AsDecorator;
Show Lines	// ... line 7
	#[AsDecorator(ButtonRemote::class)]
	final class LoggerRemote implements RemoteInterface
Show Lines	// ... lines 10 - 38