com.mle.play.json.JsonEnum.scala Maven / Gradle / Ivy

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package com.mle.play.json

import play.api.libs.json._
import play.api.libs.json.JsSuccess

/**
 *
 * @author mle
 */
trait JsonEnum[T] {
  def all: Seq[T]

  def resolveName(item: T): String

  def withName(name: String): Option[T] =
    all.find(i => resolveName(i).toLowerCase == name.toLowerCase)

  implicit object jsonFormat extends Format[T] {
    def allNames = all.map(resolveName).mkString(", ")

    override def reads(json: JsValue): JsResult[T] =
      json.validate[String].flatMap(n =>
        withName(n).map(tu => JsSuccess(tu))
          .getOrElse(JsError(s"Unknown name: $n. Must be one of: $allNames.")))

    override def writes(o: T): JsValue = Json.toJson(resolveName(o))
  }
}