How to determine the last event in a stream or projection

EventStoreDB
1

Hi,

I wanted to add a quick way to check for staleness in a aggregate without attempting a write operation so I added a couple of methods to the

GetEventStoreRepository

class.

So is there a better way to do this? Is there anything I’m missing here?

Thanks,

Chris

public bool IsStreamAt(string streamName, int version)
{
try {
var currentSlice = _eventStoreConnection.ReadStreamEventsForward(streamName, version, 1, false);
if (currentSlice.Status == SliceReadStatus.StreamNotFound) return false;
if (currentSlice.Status == SliceReadStatus.StreamDeleted) return false;
return currentSlice.IsEndOfStream;
}
catch (Exception ex) { return false; }
}

public bool TryGetstreamVersion(string streamName, out int version)
{
version = 0;
try {
var currentSlice = _eventStoreConnection.ReadStreamEventsBackward(streamName, StreamPosition.End, 1, false);
if (currentSlice.Status == SliceReadStatus.StreamNotFound) return false;
if (currentSlice.Status == SliceReadStatus.StreamDeleted) return false;
version = currentSlice.LastEventNumber;
return true;
}
catch (Exception ex) { return false; }
}

public bool IsCurrent(IAggregate aggregate)
{
if (aggregate.GetUncommittedEvents().Cast().Any()) return false;
if (aggregate.Version < 0) return false;
var streamName = _aggregateIdToStreamName(aggregate.GetType(), aggregate.Id);
return IsStreamAt(streamName, aggregate.Version);
}

``

2

Another way of doing this would be to just read back the last event in the stream and look at its version number (eg readbackwards one event)

3

Sounds good, the I’ll just wire the first function into the second,
public bool IsStreamAt(string streamName, int version)

{

int position;

return (TryGetstreamVersion(streamName, out position)) && position == version;

}

``

Thanks!

4

Actually the fastest way would be to use single event read instead of stream read. Just ReadEvent(stream, -1).