Identifies Aggregate

It is recommended to be explicit as possible when working with aggregates or domain models. Value Objects are highly recommended when identifying an aggregate or domain model. You can use any type of ID, but using UUIDs is best.

If you were creating a Post aggregate, an identifier value object would be PostId. You can simply use the AggregateId interface and implement its methods. However, it is highly recommended that you extend the abstract implementation and implement AggregateId instead:

<?php

declare(strict_types=1);

namespace App\Domain\Post\ValueObject;

use App\Domain\Post\Post;
use Codefy\Domain\Aggregate\AggregateId;
use Qubus\Exception\Data\TypeException;
use Qubus\ValueObjects\Identity\Uuid;

final class PostId extends Uuid implements AggregateId
{
    /**
     * @throws TypeException
     */
    public static function fromString(string $postId): self
    {
        return new self(value: $postId);
    }

    public function aggregateClassName(): string
    {
        return Post::className();
    }
}

The method aggregateClassName will be explained when we get to the section on creating an aggregate. But an alternative to having PostId extend Uuid, you can use Ulid instead:

<?php

declare(strict_types=1);

namespace App\Domain\Post\ValueObject;

use App\Domain\Post\Post;
use Codefy\Domain\Aggregate\AggregateId;
use Qubus\Exception\Data\TypeException;
use Qubus\ValueObjects\Identity\Ulid;

final class PostId extends Ulid implements AggregateId
{
    /**
     * @throws TypeException
     */
    public static function fromString(string $postId): self
    {
        return new self(value: $postId);
    }

    public function aggregateClassName(): string
    {
        return Post::className();
    }
}

<?php

$postId = PostId::generateAsString(); //returns a string representation of Uuid
//or
$postId = PostId::fromString('760b7c16-b28e-4d31-9f93-7a2f0d3a1c51'); //returns a PostId object
//or
$postId = PostId::fromNative('760b7c16-b28e-4d31-9f93-7a2f0d3a1c51'); //returns a ValueObject

<?php

it(description: 'should be an instance of AggregateId.', closure: function () use ($postId) {
    Assert::assertInstanceOf(expected: AggregateId::class, actual: $postId);
});

it(description: 'should be cast to a string.', closure: function () use ($postId) {
    Assert::assertEquals(expected: '760b7c16-b28e-4d31-9f93-7a2f0d3a1c51', actual: (string)$postId);
});

it('should equal instances of the same type and value.', function () use ($postId) {
    $id = PostId::fromNative($postId->toNative());

    expect(value: $postId)->toEqual(expected: $id);
});

it('should not equal instances of the same type and value.', function () use ($postId) {
    $id = PostId::fromNative('d5f77025-63d5-43a1-966e-cfe4d576ebd5');

    expect(value: $postId)->not()->toEqual(expected: $id);
});

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

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