Aggregate Repository

Since our domain will have multiple Post instances, they will need to be collected into an AggregateRepository.

But first, let’s write out our tests:

<?php

use App\Domain\Post\Post;
use App\Domain\Post\Repository\PostRepository;
use App\Domain\Post\ValueObject\PostId;
use App\Domain\Post\ValueObject\Title;
use App\Domain\Post\ValueObject\Content;
use Codefy\Domain\EventSourcing\InMemoryEventStore;
use PHPUnit\Framework\Assert;

use function expect;
use function it;

it('should reconstitute a Post to its state after persisting it.', function () {
    $postId = new PostId(value: '1cf57c2c-5c82-45a0-8a42-f0b725cfc42f');

    $post = Post::createPost(
        postId: $postId,
        title: new Title(value: 'Second Post Title'),
        content: new Content(value: 'Another short form content.')
    );

    $posts = new PostRepository(eventStore: new InMemoryEventStore());

    $posts->saveAggregateRoot(aggregate: $post);

    $reconstitutedPost = $posts->loadAggregateRoot(aggregateId: $postId);

    expect(value: $post)->toEqual(expected: $reconstitutedPost);
});

<?php

use App\Domain\Post\Post;
use Codefy\Domain\Aggregate\AggregateId;
use Codefy\Domain\Aggregate\AggregateNotFoundException;
use Codefy\Domain\Aggregate\AggregateRepository;
use Codefy\Domain\Aggregate\RecordsEvents;
use Codefy\Domain\EventSourcing\EventStore;

final class PostRepository implements AggregateRepository
{
    public function __construct(public readonly EventStore $eventStore)
    {
    }

    /**
     * Record the aggregate's latest events to
     * the event store.
     *
     * @param RecordsEvents $aggregate
     * @return void
     */
    public function saveAggregateRoot(RecordsEvents $aggregate): void
    {
        $events = $aggregate->getRecordedEvents();

        $this->eventStore->commit(events: $events);

        $aggregate->clearRecordedEvents();
    }

    /**
     * Fetch a single Post.
     *
     * @param AggregateId $aggregateId
     * @return RecordsEvents
     * @throws AggregateNotFoundException
     */
    public function loadAggregateRoot(AggregateId $aggregateId): RecordsEvents
    {
        $aggregateHistory = $this->eventStore->getAggregateHistoryFor(aggregateId: $aggregateId);
        return Post::reconstituteFromEventStream(aggregateHistory: $aggregateHistory);
    }
}

Now with our repository implemented, our tests should pass.

A complete implementation of PostRepository and InMemoryEventStore can be found on Github.

If you have any questions or issues, please feel free to post to the Documentation Forum.

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