Showcase new feature domain command handlers

Converting all use cases to use the new attribute `#[DomainCommandHandler]`,
except the classic aggregate root 'use cases' (to show both are possible).

Author: Jeroen de Graaf

README.md

@@ -10,7 +10,7 @@ Instead, a hybrid solution with aggregates and use cases is probably more likely
 This example project is using a fictive domain (taken from Sara Pellegrini's blog) where students can subscribe to courses (of any kind).
 Deliberately this is all what is defined for this domain, to focus on how this could be implemented when using Event Sourcing with the DCB pattern in mind.
 
-It contains both classic aggregates (e.g. [Course](src/Domain/Course/Course.php), [Student](src/Domain/Student/Student.php)) as well as use cases (e.g. [ChangeCourseCapacity](src/Domain/Course/ChangeCourseCapacity.php), [SubscribeStudentToCourse](src/Domain/StudentToCourseSubscription/SubscribeStudentToCourse.php), [UnsubscribeStudentFromCourse](src/Domain/StudentToCourseSubscription/UnsubscribeStudentFromCourse.php)).
+It contains both classic aggregates (e.g. [Course](src/Domain/Course/Course.php), [Student](src/Domain/Student/Student.php)) as well as use cases (e.g. [ChangeCourseCapacity](src/Domain/ChangeCourseCapacity/ChangeCourseCapacity.php), [SubscribeStudentToCourse](src/Domain/SubscribeStudentToCourse/SubscribeStudentToCourse.php), [UnsubscribeStudentFromCourse](src/Domain/UnsubscribeStudentFromCourse/UnsubscribeStudentFromCourse.php)).
 
 Inspired by other PHP libraries such as [Broadway](https://github.com/broadway), [EventSauce](https://github.com/EventSaucePHP), [Prooph](https://github.com/prooph) and [Ecotone](https://github.com/ecotoneframework) as well as [Axon Framework](https://github.com/AxonFramework) for Java.
 

config/packages/gember_event_sourcing.yaml

@@ -3,12 +3,17 @@ gember_event_sourcing:
     enabled: true
     psr6:
       service: '@cache.app'
-  event_registry:
-    reflector:
-      path: '%kernel.project_dir%/src/Domain'
+  registry:
+    event:
+      reflector:
+        path: '%kernel.project_dir%/src/Domain'
+    command_handler:
+      reflector:
+        path: '%kernel.project_dir%/src/Domain'
   message_bus:
     symfony:
       event_bus: '@event.bus'
+      command_bus: '@command.bus'
   event_store:
     rdbms:
       doctrine_dbal:

src/Application/Command/Course/ChangeCourseCapacityCommand.php

@@ -2,12 +2,16 @@
 
 declare(strict_types=1);
 
-namespace Gember\ExampleEventSourcingDcb\Domain\Course;
+namespace Gember\ExampleEventSourcingDcb\Domain\ChangeCourseCapacity;
 
+use Gember\EventSourcing\UseCase\Attribute\DomainCommandHandler;
 use Gember\EventSourcing\UseCase\Attribute\DomainEventSubscriber;
 use Gember\EventSourcing\UseCase\Attribute\DomainTag;
 use Gember\EventSourcing\UseCase\EventSourcedUseCase;
 use Gember\EventSourcing\UseCase\EventSourcedUseCaseBehaviorTrait;
+use Gember\ExampleEventSourcingDcb\Domain\Course\CourseCreatedEvent;
+use Gember\ExampleEventSourcingDcb\Domain\Course\CourseId;
+use Gember\ExampleEventSourcingDcb\Domain\Course\CourseNotFoundException;
 
 /**
  * Use case based one domain tag.
@@ -30,12 +34,13 @@ final class ChangeCourseCapacity implements EventSourcedUseCase
     /**
      * @throws CourseNotFoundException
      */
-    public function changeCapacity(int $capacity): void
+    #[DomainCommandHandler]
+    public function __invoke(ChangeCourseCapacityCommand $command): void
     {
         /*
          * Guard for idempotency.
          */
-        if ($this->capacity === $capacity) {
+        if ($this->capacity === $command->capacity) {
             return;
         }
 
@@ -47,7 +52,7 @@ public function changeCapacity(int $capacity): void
         /*
          * Apply events when all business rules are met.
          */
-        $this->apply(new CourseCapacityChangedEvent((string) $this->courseId, $capacity));
+        $this->apply(new CourseCapacityChangedEvent((string) $this->courseId, $command->capacity));
     }
 
     /**

src/Application/Command/Course/ChangeCourseCapacityHandler.php

@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Gember\ExampleEventSourcingDcb\Domain\ChangeCourseCapacity;
+
+use Gember\EventSourcing\UseCase\Attribute\DomainTag;
+use Gember\ExampleEventSourcingDcb\Domain\Course\CourseId;
+
+/**
+ * @see ChangeCourseCapacity
+ */
+final readonly class ChangeCourseCapacityCommand
+{
+    public function __construct(
+        #[DomainTag]
+        public CourseId $courseId,
+        public int $capacity,
+    ) {}
+}