public ActionResult Register(RegisterModel model) { UserAccount account = Repository.GetList().FirstOrDefault(u => u.Username == model.Username); if (account != null) { ModelState.AddModelError("Username", "Username already taken."); } if (ModelState.IsValid) { Repository.Add(model.AsUserAccount()); ShowMessage("User account registered. You can login now."); } return(RedirectToAction("login")); }