gistfile1.scala

object Protocols {
  import dispatch.json._
  trait HttpType
  implicit val HttpTypeFormat: Format[HttpType] = new Format[HttpType] {
    def reads(json: JsValue): HttpType = json match {
      case JsString("Get") => Get
      case JsString("Post") => Post
      case _ => error("Invalid HttpType")
    }
    def writes(a: HttpType): JsValue = a match {
      case Get => JsString("Get")
      case Post => JsString("Post")
    }
  }

  case object Get extends HttpType
  case object Post extends HttpType

  case class Http(url: String, t: HttpType)
  implicit val HttpFormat: Format[Http] = 
    asProduct2("url", "t")(Http)(Http.unapply(_).get)
}

// a sample test case
describe("Serialization with case objects") {
  it("should serialize") {
    import Protocols._
    val h = Http("http://www.google.com", Get)
    val h1 = fromjson[Http](tojson(h))
    h1 should equal(h)
  }
}