Json データの変換 (on Play framework 2.0.2)

test_play_json.scala

/*
  ↓こんな JSON データの変換 (Play framework 2.0.2)
  {
    "users": [
      { "name" : "krdlab", "point": 12345 },
      { "name" : "hoge",   "point":  2000 },
      ...
    ]
  }
*/

// ↓こんな感じで用意して
import play.api.libs.json.{ JsValue, JsString, JsNumber, JsObject, Format }

case class User(name: String, point: Int)

object User {
  implicit object UserFormat extends Format[User] {
    def reads(json: JsValue): User = User(
      (json \ "name").as[String],
      (json \ "point").as[Int])

    def writes(user: User): JsValue = JsObject(Seq(
      "name" -> JsString(user.name),
      "point" -> JsNumber(user.point)))
  }
}

// ↓こんな感じで呼び出す
// ----
// scala> val json = Json.parse("{\"users\":[{\"name\":\"krdlab\",\"point\":12345},{\"name\":\"hoge\",\"point\":2000}]}")
// json: play.api.libs.json.JsValue = {"users":[{"name":"krdlab","point":12345},{"name":"hoge","point":2000}]}
// 
// scala> (json \ "users").as[Array[JsObject]].map(_.as[User]).toList
// res0: List[User] = List(User(krdlab,12345), User(hoge,2000))
// ----

// [参考]
// Format:
//    http://stackoverflow.com/questions/10488950/play2-does-not-find-my-implicit-reads-or-format-for-json
// Array の読み込み:
//    https://groups.google.com/forum/?fromgroups#!topic/play-framework/BsG1tnpYgm4