public static async Task <T?> AggregateStream <T>(
this EventStoreClient eventStore,
Guid id,
CancellationToken cancellationToken,
ulong?fromVersion = null
) where T : class, IProjection
{
var readResult = eventStore.ReadStreamAsync(
Direction.Forwards,
StreamNameMapper.ToStreamId <T>(id),
fromVersion ?? StreamPosition.Start,
cancellationToken: cancellationToken
);
// TODO: consider adding extension method for the aggregation and deserialisation
var aggregate = (T)Activator.CreateInstance(typeof(T), true) !;
await foreach (var @event in readResult)
{
var eventData = @event.Deserialize();
aggregate.When(eventData !);
}
return(aggregate);
}
private async Task Store(T aggregate, CancellationToken cancellationToken)
{
var events = aggregate.DequeueUncommittedEvents();
var eventsToStore = events
.Select(EventStoreDBSerializer.ToJsonEventData).ToArray();
await eventStore.AppendToStreamAsync(
StreamNameMapper.ToStreamId <T>(aggregate.Id),
// TODO: Add proper optimistic concurrency handling
StreamState.Any,
eventsToStore,
cancellationToken : cancellationToken
);
}
