How to describe Option[FiniteDuration] in proto with scalapb - scala

Question

I am trying to use proto3 and scalapb, but I am unable to map FiniteDuration as well as unable to use it as Option. Can anyone please advise on the same
case class Message(id:Int , interval: Option[FiniteDuration])

Answer 1

Given that you configured your scalabp in sbt as described in installation guide
You need to define a custom type for a field to be converted from int64, mapped by default as Long, into FiniteDuration
For example:
syntax="proto3";
import "scalapb/scalapb.proto";
option java_package = "my.app.proto";
message Message {
int32 id = 1;
optional int64 interval = 2 [(scalapb.field).type = "scala.concurrent.duration.FiniteDuration"];
}
This will generate a case class that looks what you need.
ScalaPB will rely on implicit resolution to compile this and apply mapping from Long to FiniteDuration. For this you need to define a scalapb.TypeMapper[Long, FiniteDuration] in package object of the same package where case class is generated, ie my.app.proto.message.
package my.app.proto
import scalapb.TypeMapper
import java.util.concurrent.TimeUnit
import scala.concurrent.duration.FiniteDuration
package object message {
implicit val finiteDuration: TypeMapper[Long, FiniteDuration] =
TypeMapper[Long, FiniteDuration](s => FiniteDuration.apply(s, TimeUnit.MILLISECONDS))(_.toMillis)
}