Example Play JSON Enum reading/writing

gistfile1.scala

package enumtest


import play.api.libs.json._


object EnumUtils {
  def enumReads[E <: Enumeration](enum: E): Reads[E#Value] = new Reads[E#Value] {
    def reads(json: JsValue): JsResult[E#Value] = json match {
      case JsString(s) => {
        try {
          JsSuccess(enum.withName(s))
        } catch {
          case _: NoSuchElementException => JsError(s"Enumeration expected of type: '${enum.getClass}', but it does not appear to contain the value: '$s'")
        }
      }
      case _ => JsError("String value expected")
    }
  }

  implicit def enumWrites[E <: Enumeration]: Writes[E#Value] = new Writes[E#Value] {
    def writes(v: E#Value): JsValue = JsString(v.toString)
  }

  implicit def enumFormat[E <: Enumeration](enum: E): Format[E#Value] = {
    Format(EnumReader.enumReads(enum), EnumWriter.enumWrites)
  }
}


// Now let's test it

object EnumTest {

  object EnumA extends Enumeration {
    type EnumA = Value
    val VAL1, VAL2, VAL3 = Value
  }

  implicit val enumAFormat = EnumUtils.enumFormat(EnumA)
  val myEnumJson: JsValue = Json.toJson(EnumA.VAL1)
  val myValue: EnumA.Value = myEnumJson.asOpt[EnumA.Value].getOrElse(sys.error("Oh noes! Invalid value!"))

  def ok = EnumA.VAL1 == myValue
}

In line 26 just change the EnumReader to EnumUtils. After that you should be able to write something like this:

implicit val enumTypeFormat = EnumUtils.enumFormat(EnumClass)

At least for me it works.

Thanks, worked for me.