<?php<?phpA full-blown EventStore is out of scope for Buttercup.Protects. Here you can find a very simple InMemoryEventStore
to help us to proceed to the next part. The interface consists of a commit(DomainEvents) and a
getAggregateHistoryFor($id) method.
namespace Buttercup\Protects\Tests;
use Buttercup\Protects\AggregateHistory;
use Buttercup\Protects\DomainEvent;
use Buttercup\Protects\DomainEvents;
use Buttercup\Protects\IdentifiesAggregate;
interface EventStore
{A commit is always transactional. Either the whole set of DomainEvents is persisted, or none of them are.
Usually, a commit will consist of events from a single operation on a single Aggregate.
/**
* @param DomainEvents $events
* @return void
*/
public function commit(DomainEvents $events);The only read operation we support for now, is fetching all the events that make up the complete history of a single Aggregate instance, identified by an id.
/**
* @param IdentifiesAggregate $id
* @return AggregateHistory
*/
public function getAggregateHistoryFor(IdentifiesAggregate $id);
}
final class InMemoryEventStore implements EventStore
{We will simply store all the DomainEvents chronologically in an array, instead of persisting them in a database.
private $events = [];
public function commit(DomainEvents $events)
{
foreach ($events as $event) {
$this->events[] = $event;
}
}
public function getAggregateHistoryFor(IdentifiesAggregate $id)
{In a real implementation, we would of course query the database to only return the relevant events.
return new AggregateHistory(
$id,
array_filter(
$this->events,
function (DomainEvent $event) use ($id) { return $event->getAggregateId()->equals($id); }
));
}
}