public async Task <IActionResult> TeacherEdit(int id, TeacherNameDegreeViewModel teacher)
        {
            if (id != teacher.TeacherVMs[0].Id)
            {
                return(NotFound());
            }

            if (ModelState.IsValid)
            {
                try
                {
                    _context.Update(teacher);
                    await _context.SaveChangesAsync();
                }
                catch (DbUpdateConcurrencyException)
                {
                    if (!TeacherExists(teacher.TeacherVMs[0].Id))
                    {
                        return(NotFound());
                    }
                    else
                    {
                        throw;
                    }
                }
                return(RedirectToAction(nameof(TeacherIndex)));
            }
            return(View(teacher));
        }
        public async Task <IActionResult> TeacherIndex(string TeacherRank, string TeacherDegree, string TeacherName)
        {
            IQueryable <Teacher> teachers    = _context.Teacher.AsQueryable();
            IQueryable <string>  RankQuery   = _context.Teacher.OrderBy(m => m.AcademicRank).Select(m => m.AcademicRank).Distinct();
            IQueryable <string>  DegreeQuery = _context.Teacher.OrderBy(m => m.Degree).Select(m => m.Degree).Distinct();

            if (!string.IsNullOrEmpty(TeacherName))
            {
                teachers = teachers.Where(s => s.FirstName.Contains(TeacherName) || s.LastName.Contains(TeacherName));
            }
            if (!string.IsNullOrEmpty(TeacherDegree))
            {
                teachers = teachers.Where(x => x.Degree == TeacherDegree);
            }
            if (!string.IsNullOrEmpty(TeacherRank))
            {
                teachers = teachers.Where(x => x.AcademicRank == TeacherRank);
            }

            teachers = teachers.Include(t => t.FTCourses)
                       .Include(t => t.STCourses);
            var teachernameVM = new TeacherNameDegreeViewModel
            {
                Degrees  = new SelectList(await DegreeQuery.ToListAsync()),
                Ranks    = new SelectList(await RankQuery.ToListAsync()),
                Teachers = await teachers.ToListAsync()
            };

            return(View(teachernameVM));
        }