public async Task One_stream_can_transparently_delegate_to_another()
{
var upstream = NEventStoreStream.AllEvents(store);
store.WriteEvents(i => new AccountOpened(), 100);
var projection = new Projection <int, string>();
var dependentStream = Stream.Create <int, string>(
async q =>
{
var mapped = upstream.Map(e => new[] { e.Count() });
var batch = await mapped.Fetch(q);
return(batch);
});
var catchup = StreamCatchup.Create(dependentStream, batchSize: 50);
FetchAndSaveProjection <Projection <int, string> > manageProjection = async(id, aggregate) =>
{
await aggregate(projection);
};
catchup.Subscribe(async(p, b) =>
{
p.Value += b.Sum();
return(p);
}, manageProjection);
await catchup.RunSingleBatch();
Console.WriteLine(projection.ToLogString());
projection.Value.Should().Be(50);
projection.CursorPosition.Should().Be("50");
}
public async Task One_stream_can_use_anothers_cursor_to_limit_how_far_ahead_it_looks()
{
var aggregateId = Guid.NewGuid().ToString();
Console.WriteLine(new { aggregateId });
var upstream = NEventStoreStream.AggregateIds(store);
store.WriteEvents(i => new AccountOpened
{
AggregateId = aggregateId
}, 50);
var streamPerAggregate = upstream.IntoMany(
async(streamId, fromCursor, toCursor) =>
{
var stream = NEventStoreStream.AllEvents(store);
var cursor = Cursor.New(fromCursor);
var events = await stream.CreateQuery(cursor, int.Parse(toCursor)).NextBatch();
var s = events.Select(e => e.Body)
.Cast <IDomainEvent>()
.GroupBy(e => e.AggregateId)
.Select(group => @group.AsStream(cursorPosition: i => i.CheckpointToken));
return(s);
});
var streams = await streamPerAggregate.CreateQuery(batchSize : 25).NextBatch();
var count = 0;
foreach (var stream in streams.SelectMany(s => s))
{
count++;
var batch = await stream.CreateQuery().NextBatch();
batch.Count.Should().Be(25);
}
}
public IStream <IStream <IDomainEvent, int>, string> StreamPerAggregate()
{
return(StreamUpdates()
.IntoMany(
async(streamUpdate, fromCursor, toCursor) =>
{
var allEvents = NEventStoreStream.AllEvents(store);
var cursor = Cursor.New(fromCursor);
var batch = await allEvents.CreateQuery(cursor, int.Parse(toCursor))
.NextBatch();
var aggregate = batch.Select(e => e.Body)
.Cast <IDomainEvent>()
.Where(e => e.AggregateId == streamUpdate.StreamId);
IStream <IDomainEvent, int> stream = aggregate.AsStream(
id: streamUpdate.StreamId,
cursorPosition: e => e.StreamRevision);
return stream;
}));
}