object Gender extends Enumeration {
  type Gender = Value
  val Male = Value(0, "male")
  val Female = Value(1, "female")
  val Other = Value(2, "other")

  implicit val genderFormat = new PFormat[Gender.Value] {
    def reads(json: JsValue) = JsSuccess(Gender.withName(json.as[String]))
    def writes(myEnum: Gender.Value) = JsString(myEnum.toString)
  }
}

case class User(userName: String,
  firstName: Option[String] = None,
  lastName: Option[String] = None,
  gender: Option[Gender.Value] = None,
  imageUrl: Option[String] = None,
  tel: Option[String] = None,
  id: Long = 0L)

after saving the record in the DB, the `gender becomes Some(0/1/2)`