我正在更改ASP.NET MVC站点的新启动文件上的某些内容，但出现空错误：
System.ArgumentNullException：值不能为null。参数名称：
语境
IdentityConfig文件：
使用-
using Microsoft.AspNet.Identity.Owin;
using Microsoft.AspNet.Identity;
...剪...
public static ApplicationUserManager Create(IdentityFactoryOptions<ApplicationUserManager> options, IOwinContext context)
{
var manager = new ApplicationUserManager(new UserStore<ApplicationUser>(context.Get<IdentityDb>()));
// Configure validation logic for usernames
manager.UserValidator = new UserValidator<ApplicationUser>(manager)
{
AllowOnlyAlphanumericUserNames = false,
RequireUniqueEmail = true
};
IdentityDb文件：
public class IdentityDb : IdentityDbContext<ApplicationUser>
{
public IdentityDb()
: base("DefaultConnection")
{
}
}
我不知道Microsoft.AspNet.Identity.Owin.IdentityFactoryProvider是否缺少某些内容？
Server Error in '/' Application.
值不能为空。
参数名称：上下文
说明：执行当前Web请求期间发生未处理的异常。请查看堆栈跟踪，以获取有关错误及其在代码中起源的更多信息。
异常详细信息：System.ArgumentNullException：值不能为null。
参数名称：上下文
全栈跟踪：
Source Error:
Line 40: public static ApplicationUserManager Create(IdentityFactoryOptions<ApplicationUserManager> options, IOwinContext context)
Line 41: {
Line 42: var manager = new ApplicationUserManager(new UserStore<ApplicationUser>(context.Get<IdentityDb>()));
Line 43: // Configure validation logic for usernames
Line 44: manager.UserValidator = new UserValidator<ApplicationUser>(manager)
Source File: c:\users\aindriu\documents\visual studio 2015\Projects\Books\Books.Web\App_Start\IdentityConfig.cs Line: 42
Stack Trace:
[ArgumentNullException: Value cannot be null.
Parameter name: context]
Microsoft.AspNet.Identity.EntityFramework.UserStore`6..ctor(DbContext context) +335
Microsoft.AspNet.Identity.EntityFramework.UserStore`1..ctor(DbContext context) +5
Books.Web.ApplicationUserManager.Create(IdentityFactoryOptions`1 options, IOwinContext context) in c:\users\aindriu\documents\visual studio 2015\Projects\Books\Books.Web\App_Start\IdentityConfig.cs:42
Microsoft.AspNet.Identity.Owin.IdentityFactoryProvider`1.Create(IdentityFactoryOptions`1 options, IOwinContext context) +14
Microsoft.AspNet.Identity.Owin.<Invoke>d__0.MoveNext() +104
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +92
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58
Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.<RunApp>d__5.MoveNext() +187
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +92
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58
Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.<DoFinalWork>d__2.MoveNext() +185
Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.StageAsyncResult.End(IAsyncResult ar) +69
Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.IntegratedPipelineContext.EndFinalWork(IAsyncResult ar) +64
System.Web.AsyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +380
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155
最佳答案
为了解决此问题，我在app.CreatePerOwinContext(ApplicationDbContext.Create);中的ConfigureAuth()中添加了Startup.Auth.cs
Startup.Auth.cs
public partial class Startup
{
// For more information on configuring authentication, please visit http://go.microsoft.com/fwlink/?LinkId=301864
public void ConfigureAuth(IAppBuilder app)
{
// Configure the db context, user manager and signin manager to use a single instance per request
app.CreatePerOwinContext(ApplicationDbContext.Create);
app.CreatePerOwinContext<ApplicationUserManager>(ApplicationUserManager.Create);
app.CreatePerOwinContext<ApplicationSignInManager>(ApplicationSignInManager.Create);
// Enable the application to use a cookie to store information for the signed in user
// and to use a cookie to temporarily store information about a user logging in with a third party login provider
// Configure the sign in cookie
app.UseCookieAuthentication(new CookieAuthenticationOptions
{
AuthenticationType = DefaultAuthenticationTypes.ApplicationCookie,
LoginPath = new PathString("/Account/Login"),
Provider = new CookieAuthenticationProvider
{
// Enables the application to validate the security stamp when the user logs in.
// This is a security feature which is used when you change a password or add an external login to your account.
OnValidateIdentity = SecurityStampValidator.OnValidateIdentity<ApplicationUserManager, ApplicationUser>(
validateInterval: TimeSpan.FromMinutes(30),
regenerateIdentity: (manager, user) => user.GenerateUserIdentityAsync(manager))
}
});
app.UseExternalSignInCookie(DefaultAuthenticationTypes.ExternalCookie);
// Enables the application to temporarily store user information when they are verifying the second factor in the two-factor authentication process.
app.UseTwoFactorSignInCookie(DefaultAuthenticationTypes.TwoFactorCookie, TimeSpan.FromMinutes(5));
// Enables the application to remember the second login verification factor such as phone or email.
// Once you check this option, your second step of verification during the login process will be remembered on the device where you logged in from.
// This is similar to the RememberMe option when you log in.
app.UseTwoFactorRememberBrowserCookie(DefaultAuthenticationTypes.TwoFactorRememberBrowserCookie);
// Uncomment the following lines to enable logging in with third party login providers
//app.UseMicrosoftAccountAuthentication(
// clientId: "",
// clientSecret: "");
//app.UseTwitterAuthentication(
// consumerKey: "",
// consumerSecret: "");
//app.UseFacebookAuthentication(
// appId: "",
// appSecret: "");
//app.UseGoogleAuthentication(new GoogleOAuth2AuthenticationOptions()
//{
// ClientId = "",
// ClientSecret = ""
//});
}
}