Akka Projection EventSourcedProvider event-adapters

Akka
1

Hello!

I have recently tried out Akka Projection’s EventSourcedProvider and stumbled into some problems with typing the underlying event in the EventEnvelope. E.g. as per the documentation it is SourceProvider[Offset, EventEnvelope[ShoppingCart.Event]].

I have been trying it out in combination with akka-persistence-jdbc and typing it like that doesn’t work if I configure an event adapter for my persistence query stream.

The problem is that the EventAdapter’s fromJournal method returns an akka.persistence.journal.EventSeq which in the end is the type that I receive in the journal’s eventsByTag query and not a ShoppingCart.Event.

So instead of having EventSourcedProvider.eventsByTag[ShoppingCart.Event](..) my stream is EventSourcedProvider.eventsByTag[EventSeq](...). I wonder if there is a better way to solve this or if I am overseeing something in general.

Additionally, if this actually seems to be a problem I wonder if it would make sense to allow the configuration of a typed “EventAdapter” per EventSourcedProvider, similar as to how you configure it on an akka typed event sourced behavior:

  EventSourcedBehavior
    .apply[?, ?, ?](...)
    .eventAdapter(eventAdapter)

If the issue is unclear, I can also provide a sample project on github.

Thanks a lot!

1 Like
2

Nevermind, I saw it’s working with having an event adapter configured. I am still wondering if a typed event adapter would make sense as well, especially if you are using akka persistence typed and don’t really need the event adapter in the configuration. But this question should most likely go to the Github repository itself.