public ActionResult Login2(Authentification lg)
        {
            if (ModelState.IsValid)
            {
                using (Manage_BooksEntities conex = new Manage_BooksEntities())
                {
                    var mk = conex.Authentifications.Where(a => a.User_Name.Equals(lg.User_Name) && a.Password_cle.Equals(lg.Password_cle)).FirstOrDefault();
                    if (mk != null)
                    {
                        Session["UserId"] = mk.User_Name.ToString();


                        return(RedirectToAction("mapage"));
                    }
                }
            }
            return(View(lg));
        }