use different marshaller

akkahttpmarshaller.scala

bject WebServer extends Json4sSupport {

  def main(args: Array[String]) {

    implicit val serialization = json4s.jackson.Serialization // or native.Serialization
    implicit val formats = DefaultFormats

    implicit val system = ActorSystem("my-system")
    implicit val materializer = ActorMaterializer()
    // needed for the future flatMap/onComplete in the end
    implicit val executionContext = system.dispatcher


    val route =
      path("hello") {
        get {
          parameter('raw.as[Boolean]) { raw: Boolean =>
            raw match {
              case true =>
                // json4s is not used here, we import the default predefined marshaller 
                import akka.http.scaladsl.marshalling.PredefinedToEntityMarshallers._
                complete(Stuff("hello").body) // this will return plain text 
              case false =>
                // json4s is user here
                complete(Stuff("hello"))
            }
          }
        }
      }

    val bindingFuture = Http().bindAndHandle(route, "localhost", 8080)

    println(s"Server online at http://localhost:8080/\nPress RETURN to stop...")
    StdIn.readLine() // let it run until user presses return
    bindingFuture
      .flatMap(_.unbind()) // trigger unbinding from the port
      .onComplete(_ => system.terminate()) // and shutdown when done
  }
}