CODEWITHSUNDEEP
jsonscalaplayframeworkwebsocket
SamWiicks
SamWiicks

Reputation: 95

Scala pattern match json

im trying to use the Anonymous chat app provided by the Activator for my own purpose .i need to fire a case depending on a json field value. i have a code like this.

 def receive = LoggingReceive {
 case js: JsValue => {
  (js \ "status").validate[String] map {
    Utility.escape(_)
  }map {
    board ! Message(uid, _)
  }

i want to match the status field with string values. i tried this approach

 (js \ "status").validate[String] map {
    Utility.escape(_)
  }toString match {
    case "play" =>
      board ! Message(uid, "play")
    case "stop" =>
      board ! Message(uid, "stop")
  }

but im getting an java.nio.channels.ClosedChannelException im coming from java background and a total newbie to Scala any help would be much appriciated

Upvotes: 0

Views: 1812

Answers (1)

Mikesname
Mikesname

Reputation: 8901

You're matching against the result of validate[String], which is either JsSuccess or JsError, so I would do something like this:

(js \ "status").validate[String] match {
  case JsSuccess("play", _) => board ! Message(uid, "play")
  case JsSuccess("stop", _) => board ! Message(uid, "stop")
  case _ => // something else!
}

If "play" and "stop" are the only values you expecting you could simplify that by binding the command in the extractor directly:

(js \ "status").validate[String] match {
  case JsSuccess(cmd, _) => board ! Message(uid, cmd)
}

If you really don't care about the value of status if it doesn't exist or is something else, using asOpt instead of validate might be easier:

(js \ "status").asOpt[String].map { cmd =>
  board ! Message(uid, cmd)
}

Upvotes: 2

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