Question

我想弄清楚为什么我会收到上述错误。 ASP.NEt框架工作给了我一个很棒的Register类，但我需要创建自己的，因为我需要一个用户注册和一个商家注册到不同的角色，这是我试图在这里设置与商家注册。

所以我只是从帐户控制器复制并粘贴了Register Action。我正确地走这条路吗？而且我无法弄清楚为什么会收到此错误。

      [Authorize(Roles = "Admin")]
    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<ActionResult> Create([Bind(Include = "MerchantID,MerchantName,State,City,StreetAddress,zip,phoneNumber,email, website, Password, ConfirmPassword")] Merchant merchant)
    {

        if (ModelState.IsValid)
        {
            var _context = new ApplicationDbContext();
            var UserManager = new UserManager<ApplicationUser>(new UserStore<ApplicationUser>(_context));
            //code that I am trying to implement to add to merhcant role
            var user = new ApplicationUser { UserName = merchant.email, Email = merchant.email };
            var result = await UserManager.CreateAsync(user, merchant.Password);
            //Above code is from Register controller


            if (result.Succeeded)
            {
                //System.NullReferenceException: Object reference not set to an instance of an object.
                //SO figure out why USerManager is empty. Likely due to MerchantID not being populated yet?
                await this.UserManager.AddToRoleAsync(user.Id, merchant.MerchantName);
                var 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 this link: <a href=\"" + callbackUrl + "\">link</a>");
                ViewBag.Link = callbackUrl;
                return View("DisplayEmail");

            }

           // AddErrors(result);

                //ASP.Net provided code, don't touch.
                db.Merchants.Add(merchant);

                db.SaveChanges();
            return RedirectToAction("Index");
        }

Answer 1

您从未初始化this.UserManager。由于它是引用类型，因此其默认值为null。

你初始化一个相同名称的局部变量（这是一个非常令人困惑的事情，例如）：

var UserManager = new UserManager<ApplicationUser>(new UserStore<ApplicationUser>(_context));

但局部变量和类级变量不是一回事。初始化（和使用）类级变量：

this.UserManager = new UserManager<ApplicationUser>(new UserStore<ApplicationUser>(_context));

或使用局部变量：

await UserManager.AddToRoleAsync(user.Id, merchant.MerchantName);

System.NullReferenceException：未将对象引用设置为对象的实例。身份角色

1 个答案: