public ActionResult Index(LoginIndexModel model)
        {
            UserInfo user = this.IUserInfoDataProvider.FindUserInfoByUserNameAndPassword(model.UserName, model.Password);

            if (user != null && user.Grade == UserGrade.Admin)
            {
                FormsAuthentication.SetAuthCookie(user.ID.ToString(), true);
                return RedirectToAction("Index", "Home", null);
            }
            else if (user != null && user.Grade != UserGrade.Admin)
            {
                ViewBag.ErrorMessage = "You not permission to login the admin system.";
                model.IsFail = true;
                return View(model);
            }
            else
            {
                ViewBag.ErrorMessage = "Please check username and password is correct.";
                model.IsFail = true;
                return View(model);
            }
        }
 // GET: Login
 public ActionResult Index()
 {
     LoginIndexModel model = new LoginIndexModel();
     return View(model);
 }