Description

Proposition is to add a new #[AsMessage] attribute for messenger messages, which could serve many purposes.

Simple use case

First one here: replace the framework.messenger.routing section in configuration allowing the user to directly set the targetted transport on classes.

namespace App\Message;

use Symfony\Component\Messenger\Attribute\AsMessage;

#[AsMessage(transport: 'async')]
#[AsMessage(transport: 'other')]
#[AsMessage(transport: ['foo', 'bar'])]
class AddProduct
{
}

Easy one, using a bit of reflection to read the attribute in the Symfony\Component\Messenger\Transport\Sender\SendersLocator class is enough.

Note: I also researched a way to put this introspection inside a middle, but routing seem to happen prior to that.

@stof mentionned that messages are not services in #33912 (comment) which makes the attribute non parseable during container compilation, in this use case, that's not a problem since we can read it at runtime in the senders locator.

I think that in order to allow user to override hardcoded attributes, the framework.messenger.routing project configuration must override #[AsMessage] the attribute: this also solves some testing related use cases as mentioned by @rela589n in #33912 (comment)

More complex use cases

It was mentionned in the same issue the need be able to alias messages, for example: App\Message\AddProduct -> add_product:

namespace App\Message;

use Symfony\Component\Messenger\Attribute\AsMessage;

// Names are here for the sake of example
#[AsMessage(alias: 'add_product', legacy_aliases: ['backward_compat_add_product'])]
class AddProduct
{
}

For this to work and in order to be able to map from an alias to a PHP class name, it is required that names are registered prior runtime, hence during container compilation.

This is a problem because it forces the messages to become services. Any ideas about that ?

Example

No response