public IActionResult Edit(int id, [Bind("GradeId,StudentId,CourseId,Value")] GradeViewModel gradeViewModel)
        {
            if (id != gradeViewModel.GradeId)
            {
                return(NotFound());
            }

            if (ModelState.IsValid)
            {
                try
                {
                    _classroomService.UpdateGrade(gradeViewModel);
                }
                catch (DbUpdateConcurrencyException)
                {
                    if (!_classroomService.GradeExists(gradeViewModel.GradeId))
                    {
                        return(NotFound());
                    }
                    else
                    {
                        throw;
                    }
                }
                return(RedirectToAction(nameof(List), new { id = gradeViewModel.StudentId }));
            }

            gradeViewModel = _classroomService.GetGradeById(id);

            return(View(gradeViewModel));
        }