Add message handler

Overview

WARNING

Parts of this guide refer to the low_priority queue, which is only available in version 6.5.7.0 and above. Configuring the messenger to consume this queue will fail if it does not exist.

In this guide you'll learn how to create a message handler.

A handler gets called once the message is dispatched by the handle_messages middleware. Handlers do the actual processing of the message.

Prerequisites

As most guides, this guide is also built upon the Plugin base guide, but you don't necessarily need that. It will use an example message, so if you don't know how to add a custom message yet, have a look at our guide about Adding a message to queue. Furthermore, registering classes or services to the DI container is also not explained here, but it's covered in our guide about Dependency injection, so having this open in another tab won't hurt.

Handling messages

First, we have to create a new class which we will name SmsHandler in this example. To mark the class as message handler, we use the php attribute #[AsMessageHandler] and implement the method __invoke. We can also define multiple handlers for the same message. To register a handler, we have to tag it with the messenger.message_handler tag.

// <plugin root>/src/MessageQueue/Handler/SmsHandler.php
<?php declare(strict_types=1);

namespace Swag\BasicExample\MessageQueue\Handler;

use Symfony\Component\Messenger\Attribute\AsMessageHandler;
use Swag\BasicExample\MessageQueue\Message\SmsNotification;

#[AsMessageHandler]
class SmsHandler
{
    public function __invoke(SmsNotification $message)
    {
        // ... do some work - like sending an SMS message!
    }
}

Next steps

Now that you know how to add a message handler, you may want to add a custom middleware for your bus. To do this, head over to Add middleware guide.

If you want to learn more about configuring the message queue, have a look at the Message queue hosting guide.