I have a domain that looks like this:
package object tryme {
type ALL = AlarmMessage :+: PassMessage :+: HeyMessage :+: CNil
}
import com.tryme._
trait PayloadKind
trait Command extends PayloadKind
trait Event extends PayloadKind
trait Message[+T <: PayloadKind] {
val id: String
val payload: T
}
case class Alarm(severity: Int) extends Event
case class Pass(reason: String) extends Event
case class Hey(order: String) extends Command
case class AlarmMessage(id: String, payload: Alarm) extends Message[Event]
case class PassMessage(id: String, payload: Pass) extends Message[Event]
case class HeyMessage(id: String, payload: Hey) extends Message[Command]
case class AvroMessage(
id: String,
cargo: ALL
)
If I create an AvroMessage with cargo = HeyMessage, I'm able to serialize/de-serialse this successfully.
When I inspect the cargo field of the deserialized AvroMessage object it looks like this:
Inr(Inr(Inl(HeyMessage(art333,Hey(wow)))))
In Shapeless, how can I unwrap/strip all the Inr/Inls? Ideally I don't want to care (post de-serialization) that the payload is a HeyMessage (or any other type) if I can avoid it. I'm going to cast the cargo to Message[PayloadKind], but first I need to unwrap it.
(I saw the answer to a similar question here, but I confess I don't understand how it works, and wasn't able to adapt it.)
You can use shapeless.ops.coproduct.Selector
val coproduct = Inr(Inr(Inl(HeyMessage(art333, Hey(wow)))))
Selector[ALL, HeyMessage].apply(coproduct).get
Result is HeyMessage(art333,Hey(wow)).