Scala MultipartFormData to Json String

multipartformtojson.scala

def multipartToJsonString(req: Option[MultipartFormData[Files.TemporaryFile]]): String = {
  val jsFields = req.head.dataParts.flatMap {
    case (key, values) => values.map { value =>
      if (key == "product_id" || !isAllDigits(value)) s"""  "$key": "$value" """ // treat product_id as a string
      else s"""  "$key": ${value.toInt} """
    }
  }
  s"{${jsFields.mkString(",")}}"
}

private def isAllDigits(x: String): Boolean = x forall Character.isDigit