注册 MVC5 后向用户添加角色

Question

我想将新注册的用户添加到应用程序中的"标准"角色。但是当我尝试注册一个新用户时，我得到了一个ArgumentNullException _userManager.AddToRole(user.Id, "Standard");

这是我的代码

// POST: /Account/Register
        [HttpPost]
        [AllowAnonymous]
        [ValidateAntiForgeryToken]
        public async Task<ActionResult> Register(RegisterViewModel model)
        {
            if (ModelState.IsValid)
            {
                var user = new ApplicationUser { 
                    UserName = model.Email, 
                    Email = model.Email, 
                    PostalCode = model.PostalCode };

                var result = await UserManager.CreateAsync(user, model.Password);
                if (result.Succeeded)
                {
                    await SignInManager.SignInAsync(user, isPersistent:false, rememberBrowser:false);
                    // For more information on how to enable account confirmation and password reset please visit http://go.microsoft.com/fwlink/?LinkID=320771
                    // Send an email with this link
                    // string code = await UserManager.GenerateEmailConfirmationTokenAsync(user.Id);
                    // var callbackUrl = Url.Action("ConfirmEmail", "Account", new { userId = user.Id, code = code }, protocol: Request.Url.Scheme);
                    // await UserManager.SendEmailAsync(user.Id, "Confirm your account", "Please confirm your account by clicking <a href="" + callbackUrl + "">here</a>");
                    // Gebruiker krijgt een rol toegewezen (0,4)
                    _userManager.AddToRole(user.Id, "Standard");
                    return RedirectToAction("Index", "Home");
                }
                AddErrors(result);
            }
            // If we got this far, something failed, redisplay form
            return View(model);
        }

Answer 1

不要忘记保存您的上下文，这可能是 id 尚未知的问题。

这个代码是我一直使用的代码。

_idManager.CreateUser(newUser, model.Password);
await _db.SaveChangesAsync();
_idManager.AddUserToRole(newUser.Id, "Standard");
await _db.SaveChangesAsync();