ReactiveMongo BSON Handler for scala Map

LowPriorityMapHandlers.scala

sealed trait LowPriorityMapHandlers {

  /*
  * Item => Map("A" -> "1", "B" -> "2", "C" -> "3")
  * Json => { "A": "1", "B": "2", "C": "3"}
  */
  implicit object BSONMapHandler1 extends BSONHandler[BSONDocument, Map[String, String]] {
    override def read(bson: BSONDocument): Map[String, String] = {
      bson.elements.map {
        case (key, value) => key -> value.asInstanceOf[BSONString].value
      }.toMap
    }

    override def write(t: Map[String, String]): BSONDocument = {
      val stream: Stream[Try[(String, BSONString)]] = t.map {
        case (key, value) => Try((key, BSONString(value)))
      }.toStream
      BSONDocument(stream)
    }
  }

  /*
  * Item => Map(1 -> 1.0, 2 -> 2.0, 3 -> 3.0)
  * Json => [[1,1.0], [2,2.0], [3,3.0]]
  */
  implicit object BSONMapHandler2 extends BSONHandler[BSONValue, Map[Int, Double]] {
    override def read(bson: BSONValue): Map[Int, Double] = {
      val t = bson.seeAsTry[BSONArray] map { arr =>
        arr.values.map { tuple =>
          val tuple2 = tuple.asInstanceOf[BSONArray]
          val k = tuple2.getAs[Int](0).get
          val v = tuple2.getAs[Double](1).get
          k -> v
        }.toMap
      }
      t.get
    }
    override def write(t: Map[Int, Double]): BSONValue = {
      val elements: List[List[BSONValue]] = t.toList.map {
        case (key, value) => List(BSONInteger(key), BSONDouble(value))
      }
      BSON.write(elements)
    }
  }

}