Question

以下代码正在ASP.NET MVC 5项目中使用。每次运行以下代码时，ApplicationSignInManager类始终为null，从而导致空引用异常。作为一个相当新手我不明白在AccountController类的构造函数中调用的代码是在usermanager的实例中传递并登录管理器。也许这就是我需要关注的地方，但事实是我无法找到代码的那一部分。任何人都可以寻求帮助吗？

确切地说，从HTTPost登录方法抛出了异常。 signInManager始终为空。

var result = await SignInManager.PasswordSignInAsync(model.UserName, model.Password,
                                     model.RememberMe, shouldLockout: false);

以下是急剧代码

[Authorize]
public class AccountController : Controller
{
    private ApplicationUserManager _userManager;
    private ApplicationSignInManager _signInManager;

    public AccountController()
    {
    }

    public AccountController(ApplicationUserManager userManager, ApplicationSignInManager signInManager)
    {
        UserManager = userManager;
        SignInManager = signInManager;
    }

    //
    // GET: /Account/Login
    [AllowAnonymous]
    public ActionResult Login(string returnUrl)
    {
        ViewBag.ReturnUrl = returnUrl;
        return View();
    }


    public ApplicationSignInManager SignInManager
    {
        get
        {
            return _signInManager ?? HttpContext.GetOwinContext().Get<ApplicationSignInManager>();
        }
        private set { _signInManager = value; }
    }

    //
    // 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.UserName, 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);
        }
    }
 }

IdentityConfig的代码。

// Configure the application sign-in manager which is used in this application.
public class ApplicationSignInManager : SignInManager<ApplicationUser, string>
{
    public ApplicationSignInManager(ApplicationUserManager userManager, IAuthenticationManager authenticationManager)
        : base(userManager, authenticationManager)
    {
    }

    public override Task<ClaimsIdentity> CreateUserIdentityAsync(ApplicationUser user)
    {
        return user.GenerateUserIdentityAsync((ApplicationUserManager)UserManager);
    }

    public static ApplicationSignInManager Create(IdentityFactoryOptions<ApplicationSignInManager> options, IOwinContext context)
    {
        return new ApplicationSignInManager(context.GetUserManager<ApplicationUserManager>(), context.Authentication);
    }
}

Answer 1

检查Identity.Config.cs内的以下内容：

public static void RegisterAuth(IAppBuilder app)
{
    // other code
    app.CreatePerOwinContext<ApplicationSignInManager>(ApplicationSignInManager.Create);
    // other code
}

和项目中的某个地方（可能是Startup.cs）

[assembly: OwinStartup(typeof(Startup), "Configuration")]    
namespace YourNamespace
{
    public class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            AuthConfig.RegisterAuth(app);
        }
    }
}

Answer 2

如果该变量总是为nulla，则

可能存在问题

public ApplicationSignInManager SignInManager
    {
        get
        {
            return _signInManager ?? HttpContext.GetOwinContext().Get<ApplicationSignInManager>();
        }
        private set { _signInManager = value; }
    }

第一个ime _signInManager为空，因此如果HttpContext.GetOwinContext().Get<ApplicationSignInManager>()返回null，则您的属性将为null，并且您将收到该错误。

检查HttpContext.GetOwinContext().Get<ApplicationSignInManager>()返回的内容，并确保其值不同于null

在身份验证过程中，ApplicationSignInManager类为null

2 个答案: