Play Framework JSON Format for Case Objects - scala

Question

I have a set of case objects that inherits from a trait as below:
sealed trait UserRole
case object SuperAdmin extends UserRole
case object Admin extends UserRole
case object User extends UserRole
I want to serialize this as JSON and I just used the Format mechanism:
implicit val userRoleFormat: Format[UserRole] = Json.format[UserRole]
But unfortunately, the compiler is not happy and it says:
No unapply or unapplySeq function found
What is wrong in my case objects?

Answer 1

Ok I figured out what has to be done!
Here it is:
implicit object UserRoleWrites extends Writes[UserRole] {
def writes(role: UserRole) = role match {
case Admin => Json.toJson("Admin")
case SuperAdmin => Json.toJson("SuperAdmin")
case User => Json.toJson("User")
}
}

Answer 2

Another option is to override def toString like this:
File: Status.scala
package models
trait Status
case object Active extends Status {
override def toString: String = this.productPrefix
}
case object InActive extends Status {
override def toString: String = this.productPrefix
}
this.productPrefix will give you case object name
File: Answer.scala
package models
import play.api.libs.json._
case class Answer(
id: Int,
label: String,
status: Status
) {
implicit val answerWrites = new Writes[Answer] {
def writes(answer: Answer): JsObject = Json.obj(
"id" -> answer.id,
"label" -> answer.label,
"status" -> answer.status.toString
)
}
def toJson = {
Json.toJson(this)
}
}
File: Controller.scala
import models._
val jsonAnswer = Answer(1, "Blue", Active).toJson
println(jsonAnswer)
you get:
{"id":1,"label":"Blue","status":"Active"}
Hope this helps!