public ActionResult AddLesson(ScheduleItem schedule)
        {
            try
            {
                // TODO: Add insert logic here
                ApplicationDbContext context = ApplicationDbContext.Create();
                if (ModelState.IsValid)
                {
                    context.ScheduleItems.Add(schedule);
                }
                context.SaveChanges();

                return RedirectToAction("Index");
            }
            catch(Exception ex)
            {
                return View();
            }
        }
        public PartialViewResult _LessonForm(int semesterId, string dayOfWeek, int lessonNumber, int groupId)
        {
            Models.ScheduleItem schedule = new ScheduleItem()
            {
                SemesterId = semesterId,
                DayOfWeek = dayOfWeek,
                LessonNumber = lessonNumber,
                GroupId = groupId
            };

            ViewBag.LessonId = GetLessons();
            ViewBag.LessonType = GetLessonTypes();
            ViewBag.TeacherId = GetTeachers();
            ViewBag.ClassroomId = GetClassrooms();

            return PartialView("_LessonFormPartial", schedule);
        }