Return multiple values from a C# asynchronous method

Kushan Randima picture Kushan Randima · Sep 20, 2018 · Viewed 16.1k times · Source

I have worked with asynchronous methods and the methods which return multiple values, separately. In this specific situation, following "GetTaskTypeAndId()" method should be asynchronous and should return multiple values at the same time. How should I make this method asynchronous?

        public async Task DeleteSchoolTask(int schoolNumber, int taskDetailId)
        {  
            var result = GetTaskTypeAndId(taskDetailId); // This should be called asynchronously
            int taskId = result.Item1;
            string taskType = result.Item2;

            // step 1: delete attachment physically from server
            var fileService = new FileService(Logger, CurrentUser);
            var relativeFilePath = $"{schoolNumber}\\{Consts.RM_SCHOOL}\\{taskDetailId}";
            fileService.DeleteAttachmentFolderFromServer(Consts.CONFIG_SMP_UPLOADFILE_ROOTPATH, relativeFilePath);

            // step 2: delete records from database
            await _routineMaintenanceRepo.Value.DeleteSchoolTask(taskDetailId);
        }


        public (int, string) GetTaskTypeAndId(int taskDetailId) // How should I write this line using 'async Task'?
        {
            var detailRecord = await _routineMaintenanceRepo.Value.GetDetailRecord(taskDetailId);

            int taskId = 0;
            string taskType = "";

            switch (detailRecord.TaskType)
            {
                case 1:
                    taskId = (int)detailRecord.RoutineMaintenanceTaskId;
                    taskType = Consts.RM_DEFAULT;
                    break;
                case 2:
                    taskId = (int)detailRecord.RoutineMaintenanceTaskDuplicateId;
                    taskType = Consts.RM_DUPLICATE;
                    break;
                case 3:
                    taskId = (int)detailRecord.RoutineMaintenanceTaskSchoolId;
                    taskType = Consts.RM_SCHOOL;
                    break;
                default:
                    break;
            }
            return (taskId, taskType);
        }

Answer

Kushan Randima picture Kushan Randima · Sep 20, 2018

After playing with the code I was able to figure it out. Here is the solution.

        public async Task DeleteSchoolTask(int schoolNumber, int taskDetailId)
        {  
            var result = await GetTaskTypeAndId(taskDetailId);
            int taskId = result.Item1;
            string taskType = result.Item2;

            // step 1: delete attachment physically from server
            var fileService = new FileService(Logger, CurrentUser);
            var relativeFilePath = $"{schoolNumber}\\{Consts.RM_SCHOOL}\\{taskDetailId}";
            fileService.DeleteAttachmentFolderFromServer(Consts.CONFIG_SMP_UPLOADFILE_ROOTPATH, relativeFilePath);

            // step 2: delete records from database
            await _routineMaintenanceRepo.Value.DeleteSchoolTask(taskDetailId);
        }

        public async Task<(int, string)> GetTaskTypeAndId(int taskDetailId)
        {
            var detailRecord = await _routineMaintenanceRepo.Value.GetDetailRecord(taskDetailId);

            int taskId = 0;
            string taskType = "";

            switch (detailRecord.TaskType)
            {
                case 1:
                    taskId = (int)detailRecord.RoutineMaintenanceTaskId;
                    taskType = Consts.RM_DEFAULT;
                    break;
                case 2:
                    taskId = (int)detailRecord.RoutineMaintenanceTaskDuplicateId;
                    taskType = Consts.RM_DUPLICATE;
                    break;
                case 3:
                    taskId = (int)detailRecord.RoutineMaintenanceTaskSchoolId;
                    taskType = Consts.RM_SCHOOL;
                    break;
                default:
                    break;
            }
            return (taskId, taskType);
        }