我一直在这里关注本教程http://www.dotnetfunda.com/articles/show/2898/working-with-roles-in-aspnet-identity-for-mvc
我已经实现了所有代码和我的项目构建。但是，当我尝试将用户添加到角色，为用户获取角色或从角色中删除用户时，我收到以下错误;
Microsoft.Owin.Host.SystemWeb.dll中出现“System.NullReferenceException”类型的异常，但未在用户代码中处理 附加信息：对象引用未设置为对象的实例。
这似乎是在我的AccountController
中的UserManager中引用第47行这是我的AccountController类
[Authorize]
public class AccountController : Controller
{
private ApplicationSignInManager _signInManager;
private ApplicationUserManager _userManager;
public AccountController()
{
}
public AccountController(ApplicationUserManager userManager, ApplicationSignInManager signInManager )
{
UserManager = userManager;
SignInManager = signInManager;
}
public ApplicationSignInManager SignInManager
{
get
{
return _signInManager ?? HttpContext.GetOwinContext().Get<ApplicationSignInManager>();
}
private set
{
_signInManager = value;
}
}
public ApplicationUserManager UserManager
{
get
{
return _userManager ?? HttpContext.GetOwinContext().GetUserManager<ApplicationUserManager>();
}
private set
{
_userManager = value;
}
}
// GET: /Account/Login
[AllowAnonymous]
public ActionResult Login(string returnUrl)
{
ViewBag.ReturnUrl = returnUrl;
return View();
}
//
// POST: /Account/Login
[HttpPost]
[AllowAnonymous]
[ValidateAntiForgeryToken]
public async Task<ActionResult> Login(LoginViewModel model, string returnUrl)
{
if (!ModelState.IsValid)
{
return View(model);
}
// This doesn't count login failures towards account lockout
// To enable password failures to trigger account lockout, change to shouldLockout: true
var result = await SignInManager.PasswordSignInAsync(model.Email, model.Password, model.RememberMe, shouldLockout: false);
switch (result)
{
case SignInStatus.Success:
return RedirectToLocal(returnUrl);
case SignInStatus.LockedOut:
return View("Lockout");
case SignInStatus.RequiresVerification:
return RedirectToAction("SendCode", new { ReturnUrl = returnUrl, RememberMe = model.RememberMe });
case SignInStatus.Failure:
default:
ModelState.AddModelError("", "Invalid login attempt.");
return View(model);
}
}
//
// GET: /Account/Register
[AllowAnonymous]
public ActionResult Register()
{
return View();
}
//
// 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 };
var result = await UserManager.CreateAsync(user, model.Password);
if (result.Succeeded)
{
// comment the following line to prevent login until user confirmed
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>");
return RedirectToAction("Index", "Home");
}
AddErrors(result);
}
// If we got this far, something failed, redisplay form
return View(model);
}
// POST: /Account/LogOff
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult LogOff()
{
AuthenticationManager.SignOut(DefaultAuthenticationTypes.ApplicationCookie);
return RedirectToAction("Index", "Home");
}
//
// GET: /Account/ExternalLoginFailure
[AllowAnonymous]
public ActionResult ExternalLoginFailure()
{
return View();
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
if (_userManager != null)
{
_userManager.Dispose();
_userManager = null;
}
if (_signInManager != null)
{
_signInManager.Dispose();
_signInManager = null;
}
}
base.Dispose(disposing);
}
#region Helpers
// Used for XSRF protection when adding external logins
private const string XsrfKey = "XsrfId";
private IAuthenticationManager AuthenticationManager
{
get
{
return HttpContext.GetOwinContext().Authentication;
}
}
private void AddErrors(IdentityResult result)
{
foreach (var error in result.Errors)
{
ModelState.AddModelError("", error);
}
}
private ActionResult RedirectToLocal(string returnUrl)
{
if (Url.IsLocalUrl(returnUrl))
{
return Redirect(returnUrl);
}
return RedirectToAction("Index", "Home");
}
internal class ChallengeResult : HttpUnauthorizedResult
{
public ChallengeResult(string provider, string redirectUri)
: this(provider, redirectUri, null)
{
}
public ChallengeResult(string provider, string redirectUri, string userId)
{
LoginProvider = provider;
RedirectUri = redirectUri;
UserId = userId;
}
public string LoginProvider { get; set; }
public string RedirectUri { get; set; }
public string UserId { get; set; }
public override void ExecuteResult(ControllerContext context)
{
var properties = new AuthenticationProperties { RedirectUri = RedirectUri };
if (UserId != null)
{
properties.Dictionary[XsrfKey] = UserId;
}
context.HttpContext.GetOwinContext().Authentication.Challenge(properties, LoginProvider);
}
}
#endregion
}
}
这是我的ManageController
public class ManageController : Controller
{
private ApplicationSignInManager _signInManager;
private ApplicationUserManager _userManager;
public ManageController()
{
}
public ManageController(ApplicationUserManager userManager, ApplicationSignInManager signInManager)
{
UserManager = userManager;
SignInManager = signInManager;
}
public ApplicationSignInManager SignInManager
{
get
{
return _signInManager ?? HttpContext.GetOwinContext().Get<ApplicationSignInManager>();
}
private set
{
_signInManager = value;
}
}
public ApplicationUserManager UserManager
{
get
{
return _userManager ?? HttpContext.GetOwinContext().GetUserManager<ApplicationUserManager>();
}
private set
{
_userManager = value;
}
}
//
// GET: /Manage/Index
public async Task<ActionResult> Index(ManageMessageId? message)
{
ViewBag.StatusMessage =
message == ManageMessageId.ChangePasswordSuccess ? "Your password has been changed."
: message == ManageMessageId.SetPasswordSuccess ? "Your password has been set."
: message == ManageMessageId.SetTwoFactorSuccess ? "Your two-factor authentication provider has been set."
: message == ManageMessageId.Error ? "An error has occurred."
: message == ManageMessageId.AddPhoneSuccess ? "Your phone number was added."
: message == ManageMessageId.RemovePhoneSuccess ? "Your phone number was removed."
: "";
var userId = User.Identity.GetUserId();
var model = new IndexViewModel
{
HasPassword = HasPassword(),
PhoneNumber = await UserManager.GetPhoneNumberAsync(userId),
TwoFactor = await UserManager.GetTwoFactorEnabledAsync(userId),
Logins = await UserManager.GetLoginsAsync(userId),
BrowserRemembered = await AuthenticationManager.TwoFactorBrowserRememberedAsync(userId)
};
return View(model);
}
// GET: /Manage/ManageLogins
public async Task<ActionResult> ManageLogins(ManageMessageId? message)
{
ViewBag.StatusMessage =
message == ManageMessageId.RemoveLoginSuccess ? "The external login was removed."
: message == ManageMessageId.Error ? "An error has occurred."
: "";
var user = await UserManager.FindByIdAsync(User.Identity.GetUserId());
if (user == null)
{
return View("Error");
}
var userLogins = await UserManager.GetLoginsAsync(User.Identity.GetUserId());
var otherLogins = AuthenticationManager.GetExternalAuthenticationTypes().Where(auth => userLogins.All(ul => auth.AuthenticationType != ul.LoginProvider)).ToList();
ViewBag.ShowRemoveButton = user.PasswordHash != null || userLogins.Count > 1;
return View(new ManageLoginsViewModel
{
CurrentLogins = userLogins,
OtherLogins = otherLogins
});
}
protected override void Dispose(bool disposing)
{
if (disposing && _userManager != null)
{
_userManager.Dispose();
_userManager = null;
}
base.Dispose(disposing);
}
#region Helpers
// Used for XSRF protection when adding external logins
private const string XsrfKey = "XsrfId";
private IAuthenticationManager AuthenticationManager
{
get
{
return HttpContext.GetOwinContext().Authentication;
}
}
private void AddErrors(IdentityResult result)
{
foreach (var error in result.Errors)
{
ModelState.AddModelError("", error);
}
}
private bool HasPassword()
{
var user = UserManager.FindById(User.Identity.GetUserId());
if (user != null)
{
return user.PasswordHash != null;
}
return false;
}
private bool HasPhoneNumber()
{
var user = UserManager.FindById(User.Identity.GetUserId());
if (user != null)
{
return user.PhoneNumber != null;
}
return false;
}
public enum ManageMessageId
{
AddPhoneSuccess,
ChangePasswordSuccess,
SetTwoFactorSuccess,
SetPasswordSuccess,
RemoveLoginSuccess,
RemovePhoneSuccess,
Error
}
#endregion
}
}
然后这是我的RolesController
public class RolesController : Controller
{
ApplicationDbContext context = new ApplicationDbContext();
//
// GET: /Roles/
//[Authorize(Roles = "canEdit")]
[AllowAnonymous]
public ActionResult Index()
{
var roles = context.Roles.ToList();
return View(roles);
}
//
// GET: /Roles/Create
//[Authorize(Roles = "canEdit")]
[AllowAnonymous]
public ActionResult Create()
{
return View();
}
//
// POST: /Roles/Create
[HttpPost]
//[Authorize(Roles = "canEdit")]
[AllowAnonymous]
public ActionResult Create(FormCollection collection)
{
try
{
context.Roles.Add(new Microsoft.AspNet.Identity.EntityFramework.IdentityRole()
{
Name = collection["RoleName"]
});
context.SaveChanges();
ViewBag.ResultMessage = "Role created successfully !";
return RedirectToAction("Index");
}
catch
{
return View();
}
}
//
// GET: /Roles/Edit/5
//[Authorize(Roles = "canEdit")]
[AllowAnonymous]
public ActionResult Edit(string roleName)
{
var thisRole = context.Roles.Where(r => r.Name.Equals(roleName, StringComparison.CurrentCultureIgnoreCase)).FirstOrDefault();
return View(thisRole);
}
//
// POST: /Roles/Edit/5
//[Authorize(Roles = "canEdit")]
[AllowAnonymous]
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Edit(Microsoft.AspNet.Identity.EntityFramework.IdentityRole role)
{
try
{
context.Entry(role).State = System.Data.Entity.EntityState.Modified;
context.SaveChanges();
return RedirectToAction("Index");
}
catch
{
return View();
}
}
//
// GET: /Roles/Delete/5
//[Authorize(Roles = "canEdit")]
[AllowAnonymous]
public ActionResult Delete(string RoleName)
{
var thisRole = context.Roles.Where(r => r.Name.Equals(RoleName, StringComparison.CurrentCultureIgnoreCase)).FirstOrDefault();
context.Roles.Remove(thisRole);
context.SaveChanges();
return RedirectToAction("Index");
}
//[Authorize(Roles = "canEdit")]
[AllowAnonymous]
public ActionResult ManageUserRoles()
{
var list = context.
Roles.OrderBy(r => r.Name).ToList().Select(rr => new SelectListItem { Value = rr.Name.ToString(), Text = rr.Name }).ToList();
ViewBag.Roles = list;
return View();
}
[HttpPost]
[ValidateAntiForgeryToken]
[AllowAnonymous]
//[Authorize(Roles = "canEdit")]
public ActionResult RoleAddToUser(string UserName, string RoleName)
{
ApplicationUser user = context.Users.Where(u => u.UserName.Equals(UserName, StringComparison.CurrentCultureIgnoreCase)).FirstOrDefault();
var account = new AccountController();
account.UserManager.AddToRole(user.Id, RoleName);
ViewBag.ResultMessage = "Role created successfully !";
// prepopulat roles for the view dropdown
var list = context.Roles.OrderBy(r => r.Name).ToList().Select(rr => new SelectListItem { Value = rr.Name.ToString(), Text = rr.Name }).ToList();
ViewBag.Roles = list;
return View("ManageUserRoles");
}
[HttpPost]
[ValidateAntiForgeryToken]
//[Authorize(Roles = "canEdit")]
[AllowAnonymous]
public ActionResult GetRoles(string UserName)
{
if (!string.IsNullOrWhiteSpace(UserName))
{
ApplicationUser user = context.Users.Where(u => u.UserName.Equals(UserName, StringComparison.CurrentCultureIgnoreCase)).FirstOrDefault();
var account = new AccountController();
ViewBag.RolesForThisUser = account.UserManager.GetRoles(user.Id);
// prepopulat roles for the view dropdown
var list = context.Roles.OrderBy(r => r.Name).ToList().Select(rr => new SelectListItem { Value = rr.Name.ToString(), Text = rr.Name }).ToList();
ViewBag.Roles = list;
}
return View("ManageUserRoles");
}
[HttpPost]
[ValidateAntiForgeryToken]
// [Authorize(Roles = "canEdit")]
[AllowAnonymous]
public ActionResult DeleteRoleForUser(string UserName, string RoleName)
{
var account = new AccountController();
ApplicationUser user = context.Users.Where(u => u.UserName.Equals(UserName, StringComparison.CurrentCultureIgnoreCase)).FirstOrDefault();
if (account.UserManager.IsInRole(user.Id, RoleName))
{
account.UserManager.RemoveFromRole(user.Id, RoleName);
ViewBag.ResultMessage = "Role removed from this user successfully !";
}
else
{
ViewBag.ResultMessage = "This user doesn't belong to selected role.";
}
// pre populates roles for dropdown
var list = context.Roles.OrderBy(r => r.Name).ToList().Select(rr => new SelectListItem { Value = rr.Name.ToString(), Text = rr.Name }).ToList();
ViewBag.Roles = list;
return View("ManageUserRoles");
}
}
我相信我已经正确地跟踪了样本，并且我已经检查过我的代码与示例中显示的相同，所以我不明白为什么它不起作用。我试图创建一个ApplicationUserManager的新实例，看看是否有帮助，但这只会产生另一个错误。任何帮助解决这个问题将非常感谢！