Play [Scala]: How to flatten a JSON object

Question

Given the following JSON...

{
  \"metadata\": {
    \"id\": \"1234\",
    \"type\": \"file\",
    \"length\": 395
  }
}

... how do I convert it

Answer 1

Based on previous solutions, have tried to simplify the code a bit

  def getNewKey(oldKey: String, newKey: String): String = {
    if (oldKey.nonEmpty) oldKey + "." + newKey else newKey
  }

  def flatten(js: JsValue, prefix: String = ""): JsObject = {
    if (!js.isInstanceOf[JsObject]) return Json.obj(prefix -> js)
    js.as[JsObject].fields.foldLeft(Json.obj()) {
      case (o, (k, value)) => {
        o.deepMerge(value match {
          case x: JsArray => x.as[Seq[JsValue]].zipWithIndex.foldLeft(o) {
            case (o, (n, i: Int)) => o.deepMerge(
              flatten(n.as[JsValue], getNewKey(prefix, k) + s"[$i]")
            )
          }
          case x: JsObject => flatten(x, getNewKey(prefix, k))
          case x => Json.obj(getNewKey(prefix, k) -> x.as[JsValue])
        })
      }
    }
  }