Play2.1 JSON API: Reads a JsArray and then map on its elements applying Reads (cumulating errors)

gistfile1.scala

// maybe we could add this one into Play...
// Reads a JsArray and then map on its elements applying Reads (cumulating errors)
def readJsArrayMap[A <: JsValue](transformEach: Reads[A]): Reads[JsArray] = Reads { js => js match {
  case arr: JsArray =>
    arr.value.foldLeft(JsSuccess(Seq[JsValue]()): JsResult[Seq[JsValue]]) { (acc, e) => 
      acc.flatMap{ seq => 
        e.transform(transformEach).map( v => seq :+ v )
      }
    }.map(JsArray(_))
  case _ => JsError("expected JsArray")
}}

// yours specific reader
val myReads = (__ \ "key1").json.pickBranch(
  readJsArrayFoldLeft(
    (__ \ "key2").json.pickBranch(
      readJsArrayFoldLeft(
        (__ \ "id").json.copyFrom(__.json.pick)
      )
    )
  )
)

I don't suppose this is any closer to making into Play, like your comments suggest? I found the helper method to be very useful for transforming a JsArray as output for my web services.

Thanks,
David P.