public async Task <TEventSourcedAggregate?> GetAsync(TId id, CancellationToken token = default)
{
var streamName = GetStreamName(id);
var readStreamResult = _client.ReadStreamAsync(Direction.Forwards, streamName, StreamPosition.Start, cancellationToken: token);
if (await readStreamResult.ReadState is ReadState.StreamNotFound)
{
return(null);
}
TEventSourcedAggregate?aggregate = null;
await foreach (var resolvedEvent in readStreamResult)
{
var(@event, metadata) = EventStoreSerializer.Deserialize(resolvedEvent.Event);
if (RequestContext.RequestId is not null && RequestContext.RequestId == metadata.CausationId)
{
throw new DuplicateRequestException(RequestContext.RequestId);
}
aggregate ??= (TEventSourcedAggregate)Activator.CreateInstance(typeof(TEventSourcedAggregate), true) !;
aggregate.ApplyEvent(@event);
}
return(aggregate);
}
public async Task SaveAsync(TEventSourcedAggregate aggregate, CancellationToken token = default)
{
if (!aggregate.UncommittedEvents.Any())
{
return;
}
var streamName = GetStreamName(aggregate.Id);
var originalAggregateVersion = aggregate.Version - aggregate.UncommittedEvents.Count;
var expectedStreamRevision = originalAggregateVersion is 0
? StreamRevision.None
: new StreamRevision((ulong)originalAggregateVersion - 1);
var metadata = new EventMetadata(
CausationId: RequestContext.RequestId,
CorrelationId: RequestContext.CorrelationId);
var eventsToSave = aggregate.UncommittedEvents.Select(@event => EventStoreSerializer.Serialize(@event, metadata));
try
{
await _client.AppendToStreamAsync(streamName, expectedStreamRevision, eventsToSave, cancellationToken : token);
}
catch (WrongExpectedVersionException e)
when(e.ExpectedStreamRevision == StreamRevision.None)
{
throw new Exceptions.DuplicateKeyException(aggregate.Id);
}
aggregate.MarkEventsAsCommitted();
}
