public async Task LoadAsync(CourseArgs args)
        {
            ViewModelArgs = args ?? CourseArgs.CreateDefault();

            if (ViewModelArgs.IsNew)
            {
                Item = null;
            }
            else
            {
                try
                {
                    Item = await StudentScoreService.GetCourseAsync(ViewModelArgs.CourseId);
                }
                catch (Exception e)
                {
                    await DialogService.ShowAsync("载入失败", e.InnerException?.Message ?? e.Message);
                }
            }
        }
 public StudentCourseRecordListViewModel(IDialogService dialogService, IStudentScoreService studentScoreService) : base(dialogService)
 {
     StudentScoreService    = studentScoreService;
     CourseDetailsViewModel = new CourseDetailsViewModel(dialogService, studentScoreService);
     Args = new CourseArgs();
 }