CODEWITHSUNDEEP
jsonscalaakkamarshallingspray
Lucian Enache
Lucian Enache

Reputation: 2530

Akka-Spray object marshall

I am experimenting with aka and spray, what I want to achieve is a simple object marshalling service.

When I try to compile the code I get the following error :

Error:(33, 18) could not find implicit value for parameter marshaller:
  spray.httpx.marshalling.Marshaller[ExampleApplication.Password]
  marshal(Password(randomString(8),i,0))
                   ^

Here is the code: 

import akka.actor.ActorSystem
import spray.http.HttpEntity
import spray.json.DefaultJsonProtocol
import spray.routing.SimpleRoutingApp
import spray.httpx.marshalling._
import spray.json._

object ExampleApplication extends App with SimpleRoutingApp {
  implicit val actorSystem = ActorSystem()
  implicit var i = 0;


  object MyJsonProtocol extends DefaultJsonProtocol {
    implicit val PasswordFormat = jsonFormat3(Password)
  }

  case class Password(pass: String, count: Int, complexity: Int)

  def newPass(cplx: Int):Password = {return Password(randomString(cplx),i,0)}

  startServer(interface = "localhost", port = 8080) {
    get {
      path("passgen") {
        i+=1
        complete {
          marshal(newPass(8))
        }
      }
    }
  }

  def randomString(n: Int): String = {
    n match {
      case 1 => util.Random.nextPrintableChar().toString
      case _ => util.Random.nextPrintableChar.toString ++ randomString(n - 1).toString
    }
  }
}

I'm still failing to understand what's going wrong.

Upvotes: 1

Views: 559

Answers (1)

Gangstead
Gangstead

Reputation: 4182

Two changes to fix it:

import spray.httpx.SprayJsonSupport._

Then even though you define the JsonProtocol object right in your app you must still import it's members explicitly: 

object MyJsonProtocol extends DefaultJsonProtocol {
  implicit val PasswordFormat = jsonFormat3(Password)
}
import MyJsonProtocol._

That looks a little repetitive in this case, but in most use cases you'll have it defined somewhere else.

Optional

You can complete the call without explicitly calling marshal:

complete {
  newPass(8)
}

Upvotes: 2

Related Questions