// GET: Chapter
        public ActionResult Index(int?subjectId, int?classId)
        {
            ViewBag.ClassList = (from c in _classService.GetClasses()
                                 select new SelectListItem
            {
                Value = c.ClassId.ToString(),
                Text = c.Name
            }).ToList();

            ViewBag.ClassId   = classId;
            ViewBag.SubjectId = subjectId;
            var chapters      = (classId == null && subjectId == null) ? _chapterService.GetAllChapters().ToList() : _chapterService.GetChapters((int)subjectId, (int)classId).ToList();
            var viewModelList = AutoMapper.Mapper.Map <List <ChapterProjection>, ChapterViewModel[]>(chapters);

            return(View(viewModelList));
        }