New in Symfony 6.4: More Built-in Message Handlers

November 10, 2023 • Published by Javier Eguiluz

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Contributed by
Kevin Bond
in #49813, #49814 and #49815.

The Messenger component is designed around two main concepts: messages (which are the classes that hold the data) and handlers (which are the classes called when the message is dispatched).

In Symfony 6.4 we're introducing some new built-in handlers so you can use those features in your applications without having to implement them.

Run Process Handler

This handler creates a new process with the given information and runs it using the Process component:

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        use Symfony\Component\Messenger\MessageBusInterface;
use Symfony\Component\Process\Messenger\RunProcessMessage;

class SomeService
{
    public function __construct(private readonly MessageBusInterface $bus)
    {
    }

    public function cleanUp(): void
    {
        // once handled, it returns a RunProcessContext object with information
        // such as the exit code, the output content, etc.
        $this->bus->dispatch(new RunProcessMessage(
            ['rm', '-rf', 'var/log/temp/*'],
            cwd: '/my/custom/working-dir'
        ));

        // ...
    }
}
    

Run Command Handler

This handler runs the given command name and arguments as a terminal command using the Console component:

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        use Symfony\Component\Console\Messenger\RunCommandMessage;
use Symfony\Component\Messenger\MessageBusInterface;

class SomeService
{
    public function __construct(private readonly MessageBusInterface $bus)
    {
    }

    public function cleanUp(): void
    {
        // ...

        // once handled, it returns a RunCommandContext object with information
        // such as the exit code, the output content, etc.
        $this->bus->dispatch(new RunCommandMessage('app:my-cache:clean-up --dir=var/temp'));
        $this->bus->dispatch(new RunCommandMessage('cache:clear'));
    }
}
    

The RunCommandMessage class defines the $throwOnFailure and $catchExceptions constructor arguments so you can better control what to do when an error happens.

Ping Webhook Handler

This handler pings the given webhook URL using the HttpClient component. Combine it with the Scheduler component to ping the URL repeatedly:

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        use Symfony\Component\HttpClient\Messenger\RPingWebhookMessage;
use Symfony\Component\Messenger\MessageBusInterface;

class SomeService
{
    public function __construct(private readonly MessageBusInterface $bus)
    {
    }

    public function ping(): void
    {
        // An HttpExceptionInterface is thrown on 3xx/4xx/5xx
        $this->bus->dispatch(new PingWebhookMessage('GET', 'https://example.com/status');

        // Ping, but does not throw on 3xx/4xx/5xx
        $this->bus->dispatch(new PingWebhookMessage('GET', 'https://example.com/status', throw: false);
    }
}
    

Published in #Living on the edge

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Comments

Kai Eichinger said on Nov 10, 2023 at 16:32

Very useful! Is there a docs site somewhere that lists all built-in message handlers across all components? It's kind of hard to keep track of.

Jérôme Tamarelle said on Nov 10, 2023 at 17:05

It's great seeing the named arguments used like this in the examples.

Laurent VOULLEMIER Certified said on Nov 11, 2023 at 08:56

@Kai bin/console debug:container --tag messenger.message_handler should do the job.

David Gorges said on Nov 20, 2023 at 22:03

Really excited about the new PingWebhookMessage in Symfony 6.4! It's a great tool for monitoring cron jobs. The addition of payload customization through the $options argument is nice little touch. It's great to see the integration of the messenger, httpclient, and scheduler components that allows such a useful handler in like 2 lines of code.

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