public ActionResult Index(User obj1)
        {
            if (ModelState.IsValid)
            {
                using (StudentMSEntities db = new StudentMSEntities())
                {
                    var obj = db.Users.Where(a => a.Username.Equals(obj1.Username) && a.Password.Equals(obj1.Password)).FirstOrDefault();
                    if (obj != null)
                    {
                        Session["UserId"]   = obj.Id.ToString();
                        Session["Username"] = obj.Username.ToString();
                        return(RedirectToAction("Index", "Home"));
                    }
                    else
                    {
                        ModelState.AddModelError("", "The username or password is incorrect");
                    }
                }
            }

            return(View(obj1));
        }