How to describe Option[FiniteDuration] in proto with scalapb

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)
}