AggregateRoot versioning causes ConcurrencyException about cqrslite HOT 5 CLOSED

Can you try to just add .Where(x => x.Version > fromVersion) to the bottom of your method?

from cqrslite.

OK, so IEventStore.Get, in the sample, only loads those events that haven't already been loaded?

My implementation of IEventStore.Get just now reads all events related to the stream for that aggregate:

        public async Task<IEnumerable<IEvent>> Get(Guid aggregateId, int fromVersion)
        {
            var streamEvents = new List<ResolvedEvent>();

            StreamEventsSlice currentSlice;
            var nextSliceStart = (long)StreamPosition.Start;
            do
            {
                currentSlice = await _connection.ReadStreamEventsForwardAsync(
                    StreamName($"booking-{aggregateId}"), nextSliceStart, 200, false);

                nextSliceStart = currentSlice.NextEventNumber;

                streamEvents.AddRange(currentSlice.Events);
            } while (!currentSlice.IsEndOfStream);

            return streamEvents.Select(e => (BaseEvent)RebuildEvent(e));
        }

This is pretty much just a lift and drop from the Event Store documentation (http://docs.geteventstore.com/dotnet-api/4.0.0/reading-events/).

The input for fromVersion will be 0 given that that's the expected version.

from cqrslite.

Yes I can! That fixes it.

Ok, understanding adjusted I think. IEventStore.Get MUST only return those events that have a version greater than that passed in. I was going on the assumption that I could ignore the fromVersion for the time being assuming it was just a convenience provided to improve performance, but it's actually linked to the successful saving of the new events.

Thanks for your help and the prompt replies!

from cqrslite.

What does _eventStore.Get return in the method you are asking for and what is the input? The implementation in the sample is like this events?.Where(x => x.Version > fromVersion) ?? new List<IEvent>(), so it only returns the events saved after the current version.

from cqrslite.

Yes, that's the way it is now. It could possibly be moved into the repository as well, but where put there for performance reasons, so the eventstore would not necessarily need to load all events every time.

from cqrslite.