json - Play Framework : How to serialize/deserialize an enumeration to/from JSON

Question

鉴于以下枚举...

object MyEnum extends Enumeration {

  type MyEnum = Value

  val Val1 = Value("val1")
  val Val2 = Value("val2")
  val ValN = Value("valN")

  implicit val myEnumFormat = new Format[MyEnum] {
    def reads(json: JsValue) = MyEnum.withName(json.as[String].value) // doesn't compile
    def writes(myEnum: MyEnum) = JsString(myEnum.toString)
  }
}

...我需要将其序列化/反序列化到 JSON 或从 JSON 序列化/反序列化。 myEnumFormat 无法编译，我总是收到以下错误消息:

type mismatch;
[error]  found   : models.MyEnum.Value
[error]  required: play.api.libs.json.JsResult[models.MyEnumValue]
[error]  Note: implicit value myEnumFormat is not applicable here because it comes after the application point and it lacks an explicit result type
[error]     def reads(json: JsValue) = MyEnum.withName(json.as[JsString].value)

我错过了什么吗？

Answer 1

implicit val genderReads = Reads.enumNameReads(Gender) 对我来说工作正常。玩 Scala 2.4.2