public async Task <IActionResult> Index(string searchStringName, string searchStringSurname, string searchStudentId)
        {
            //return View(await _context.Student.ToListAsync());

            IQueryable <Student> students = _context.Student.AsQueryable();

            if (!string.IsNullOrEmpty(searchStringName))
            {
                students = students.Where(s => s.FirstName.Contains(searchStringName));
            }
            if (!string.IsNullOrEmpty(searchStringSurname))
            {
                students = students.Where(s => s.LastName.Contains(searchStringSurname));
            }
            if (!string.IsNullOrEmpty(searchStudentId))
            {
                students = students.Where(s => s.StudentId.Contains(searchStudentId));
            }
            var studentNameIdVM = new StudentNameIdViewModel
            {
                Students = await students.ToListAsync()
            };

            return(View(studentNameIdVM));
        }
        public async Task <IActionResult> StudentIndex(string StudentName, string StudentIDs)
        {
            IQueryable <Student> students = _context.Student.AsQueryable();
            IQueryable <string>  IDQuery  = _context.Student.OrderBy(m => m.StudentId).Select(m => m.StudentId).Distinct();

            if (!string.IsNullOrEmpty(StudentName))
            {
                students = students.Where(s => s.FirstName.Contains(StudentName) || s.LastName.Contains(StudentName));
            }

            if (!string.IsNullOrEmpty(StudentIDs))
            {
                students = students.Where(x => x.StudentId == StudentIDs);
            }

            //students = students.Include(s => s.Courses).ThenInclude(s => s.Course);

            var studentnameVM = new StudentNameIdViewModel
            {
                IDs      = new SelectList(await IDQuery.ToListAsync()),
                Students = await students.ToListAsync()
            };

            return(View(studentnameVM));;
        }