Akka persistence and deserialization

EventStoreDB
1

Hi

I am testing akka persistence with eventstore.

My problem is that i can’t seem to figure out what akka persistence saves as event data.

My events are ScalaPB classes, and should be serialized to protobuffer. But i am having difficulty deseralizing them, in my own code. Akka persistence works as it should.

It seems to be protobuffer binary format , but is my event wrapped in some other class?
I have tried:
val serializa1tion = SerializationExtension(context.system)
val event = serialization.deserialize(e.linkedEvent.data.data.value.toArray, myeventclass)
But then it tries java serialization and fails.

Some help would be great.

2

Your event is wrapped by PersistentRepr, so you need to account for that.

3

Try this:

val serialization: Serialization = SerializationExtension(context.system)

def deserialize[A](bytes: Array[Byte])(implicit ct: ClassTag[A]): Try[A] =

serialization.deserialize(bytes, ct.runtimeClass).asInstanceOf[Try[A]]

val x = for {

pr <- deserializePersistentRepr

} yield pr.payload

4

I lifted the protobuf serializer from akka-remoting and adjusted it to work with ScalaPB, see here: https://gist.github.com/ahjohannessen/ce43cf45607b9dd9050b

5

Furthermore, then you also need to instruct Akka serialization to use that serializer, like this:

akka {

actor {

serializers {

  proto = "your.namespace.ProtobufSerializer"

}

serialization-bindings {

  "com.trueaccord.scalapb.GeneratedMessage" = proto

  "java.io.Serializable"                    = none // because it is a bad default

}

}

}

Hopefully that should get you going :slight_smile:

6

Thanks this was exactly what i was looking for.