public static string GetPlayList() //OK

        {
            DataTable dtPlayList = new SongReps().GetPlayList();

            return(CnvDataTableToJsonString(dtPlayList));
        }
        public static string GetUserLibrary(string json_userID) //OK

        {
            long userID = long.Parse(GetSingleValueFromJson(json_userID, "userID"));

            UserDataObj user = new UserDataObj();

            user.UserID = userID;

            DataTable dtSongs = new SongReps().GetUserLibrary(user);

            return(CnvDataTableToJsonString(dtSongs));
        }