public void SetStudentList()
        {
            var stds = StudentRepo.FindByQuery(" ClassID = " + SelectedClassID);

            if (stds != null)
            {
                List<CustomDropDownValues> _list = new List<CustomDropDownValues>();
                foreach (var item in stds)
                {
                    CustomDropDownValues _temp = new CustomDropDownValues { DisplayName = item.FullName, DisplayID = item.StudentID.ToString() };
                    _list.Add(_temp);
                }
                StudentDropDown = _list;
            }
            else { StudentDropDown = null; }

        }
        public void SetSubjectList(int classID)
        {
            var subjects = ClassSubjectRepo.GetSelectedSubjects(classID);

            if (subjects != null)
            {
                List<CustomDropDownValues> _list = new List<CustomDropDownValues>();
                foreach (var item in subjects)
                {
                    CustomDropDownValues _temp = new CustomDropDownValues { DisplayName = item.Description, DisplayID = item.SubjectID.ToString() };
                    _list.Add(_temp);
                }
                SubjectDropDown = _list;
            }
            else { SubjectDropDown = null; }
        }