06. Introduction of CommandBus

config/packages/messenger.yaml

@@ -6,6 +6,12 @@ framework:
         buses:
             default:
                 default_middleware: allow_no_handlers
+            command_bus:
+                middleware:
+                    - validation
+                    - doctrine_ping_connection
+                    - doctrine_close_connection
+                    - doctrine_transaction
 
         transports:
             # https://symfony.com/doc/current/messenger.html#transport-configuration

src/App/Controller/PostFollowersController.php

@@ -4,8 +4,8 @@ declare(strict_types=1);
 
 namespace App\Controller;
 
+use Cheeper\Application\CommandBus;
 use Cheeper\Application\Follow\FollowCommand;
-use Cheeper\Application\Follow\FollowCommandHandler;
 use Cheeper\DomainModel\Author\AuthorDoesNotExist;
 use OpenApi\Attributes as OA;
 use Psl\Json;
@@ -20,8 +20,8 @@ use Symfony\Component\Validator\Validator\ValidatorInterface;
 final class PostFollowersController extends AbstractController
 {
     public function __construct(
-        private readonly FollowCommandHandler $followCommandHandler,
         private readonly ValidatorInterface $validator,
+        private readonly CommandBus $commandBus,
     ) {
     }
 
@@ -95,7 +95,7 @@ final class PostFollowersController extends AbstractController
         }
 
         try {
-            ($this->followCommandHandler)(
+            $this->commandBus->handle(
                 new FollowCommand(
                     $data['from_author_id'],
                     $data['to_author_id']

src/Cheeper/Application/CommandBus.php

@@ -0,0 +1,12 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Cheeper\Application;
+
+/** @template T of Command */
+interface CommandBus
+{
+    /** @psalm-param T $command */
+    public function handle(Command $command): void;
+}

src/Cheeper/Application/Follow/FollowCommandHandler.php

@@ -10,7 +10,9 @@ use Cheeper\DomainModel\Author\AuthorDoesNotExist;
 use Cheeper\DomainModel\Author\AuthorId;
 use Cheeper\DomainModel\Author\AuthorRepository;
 use Cheeper\DomainModel\Follow\FollowRepository;
+use Symfony\Component\Messenger\Attribute\AsMessageHandler;
 
+#[AsMessageHandler]
 final class FollowCommandHandler
 {
     public function __construct(

src/Cheeper/Infrastructure/Application/SymfonyMessengerCommandBus.php

@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Cheeper\Infrastructure\Application;
+
+use Cheeper\Application\Command;
+use Cheeper\Application\CommandBus;
+use Symfony\Component\Messenger\MessageBusInterface;
+
+final class SymfonyMessengerCommandBus implements CommandBus
+{
+    public function __construct(
+        private readonly MessageBusInterface $commandBus
+    ) {
+    }
+
+    public function handle(Command $command): void
+    {
+        $this->commandBus->dispatch($command);
+    }
+}