Question

This is my Cout object:

case class Cout (idCout:Int, cout:String)

object Cout{

  implicit object CoutFormat extends Format[Cout] {
    def reads(json: JsValue): Cout = Cout(
      (json \ "idCout").as[Int],
      (json \ "cout").as[String]
    )

    def writes(s: Cout): JsValue = JsObject(Seq(
      "id" -> JsNumber(s.idCout),
      "cout" -> JsString(s.cout)
    ))
  }
}

I’m trying to use this class when calling a webservice using WS:

val cout = response.json.as[Cout]

But the scala compiler keeps complaining:

[RuntimeException: Int expected]

on the line (json \ "idCout").as[Int],

Could anybody tell me what I’m doing wrong?

• got the example from https://sites.google.com/site/play20zh/scala-developers/working-with-json

Answer 1

You have a typo in your Format instance: you’re writing an "id" field but trying to read one named "idCout". Change one of them:

case class Cout (idCout: Int, cout: String)

object Cout {
  implicit object CoutFormat extends Format[Cout] {
    def reads(json: JsValue): Cout = Cout(
      (json \ "idCout").as[Int],
      (json \ "cout").as[String]
    )

    def writes(s: Cout): JsValue = JsObject(Seq(
      "idCout" -> JsNumber(s.idCout),
      "cout" -> JsString(s.cout)
    ))
  }
}

And it works:

scala> Json.toJson(Cout(1, "test")).as[Cout]
res0: Cout = Cout(1,test)