I am still a beginner and MVC entity framework when adding a user I want to check if UserName and email already exists or not. if there is a message is displayed . the addition is done correctly in database my preblème basis just to do the test on the presence of username and email ; if gasket Service class that CONTAIN the method and my controller if quelq'un peuc help me please

my class service
 
 public void Create(User item)     {         item.Password = Cryptography.HashPassword(item.Password);         var list = _userRepository.Get().ToList();         var Result = list.Where(user => user.UserName == item.UserName);
          if (Result != null)        return;         else         {             _userRepository.Create(item);         }     }
My controller

[HttpPost]     public ActionResult Create(User user, HttpPostedFileBase avatarfile, IEnumerable roles, bool? createResource)     {         if (avatarfile != null)         {             user.Avatar = Guid.NewGuid() + Path.GetExtension(avatarfile.FileName);             var filePath = Constants.PhotoFolder + user.Avatar;             avatarfile.SaveAs(Server.MapPath(filePath));         }         else         {             user.Avatar = "default-avatar.png";         }           var result = ValidationHelper.Validate(user);         if (!result.IsValid)         {             ViewBag.Result = Constants.Failure;             ViewBag.Errors = ValidationHelper.GetError(result);             return View();         }              _userService.Create(user);