UUID

A UUID can be generated for the aggregateId. There are two popular libraries that can be used:

• ramsey/uuid
• symfony/uid

The aggregate does not care how the id is generated, since only an aggregate-wide unique string is expected here.

use Patchlevel\EventSourcing\Aggregate\AggregateRoot;
use Patchlevel\EventSourcing\Attribute\Aggregate;
use Patchlevel\EventSourcing\Attribute\Apply;
use Ramsey\Uuid\Uuid;
use Ramsey\Uuid\UuidInterface;

#[Aggregate('profile')]
final class Profile extends AggregateRoot
{
    private UuidInterface $id;
    private string $name;

    public function aggregateRootId(): string
    {
        return $this->id->toString();
    }

    public function id(): UuidInterface 
    {
        return $this->id;
    }

    public function name(): string 
    {
        return $this->name;
    }

    public static function create(string $name): self
    {
        $id = Uuid::uuid4();

        $self = new self();
        $self->recordThat(new ProfileCreated($id, $name));

        return $self;
    }

    #[Apply]
    protected function applyProfileCreated(ProfileCreated $event): void 
    {
        $this->id = $event->profileId();
        $this->name = $event->name();
    }
}

Or even better, you create your own aggregate-specific id class. This allows you to ensure that the correct id is always used. The whole thing looks like this:

use Ramsey\Uuid\Uuid;

class ProfileId 
{
    private string $id;

    public function __construct(string $id) 
    {
        $this->id = $id;
    }

    public static function generate(): self 
    {
        return new self(Uuid::uuid4()->toString());
    }

    public function toString(): string 
    {
        return $this->id;
    }
}

use Patchlevel\EventSourcing\Aggregate\AggregateRoot;
use Patchlevel\EventSourcing\Attribute\Aggregate;
use Patchlevel\EventSourcing\Attribute\Apply;

use Ramsey\Uuid\UuidInterface;

#[Aggregate('profile')]
final class Profile extends AggregateRoot
{
    private ProfileId $id;
    private string $name;

    public function aggregateRootId(): string
    {
        return $this->id->toString();
    }

    public function id(): ProfileId 
    {
        return $this->id;
    }

    public function name(): string 
    {
        return $this->name;
    }

    public static function create(string $name): self
    {
        $id = ProfileId::generate();

        $self = new self();
        $self->recordThat(new ProfileCreated($id, $name));

        return $self;
    }

    #[Apply]
    protected function applyProfileCreated(ProfileCreated $event): void 
    {
        $this->id = $event->profileId();
        $this->name = $event->name();
    }
}

Note

If you want to use snapshots, then you have to make sure that the value objects are normalized. You can find how to do this here.