FormsAuthentication.SetAuthCookie在异步操作中抛出NullReferenceException

Question

我发现FormsAuthentication.SetAuthCookie抛出NullReferenceException - 对象引用未设置为azure网站上异步操作内的对象实例。

我发现了以下内容：

http://connect.microsoft.com/VisualStudio/feedback/details/743350/formsauthentication-setauthcookie-throws-nullreferenceexception-if-called-in-an-async-action-in-mvc4

但我已经

了

 <appSettings>
    <add key="aspnet:UseTaskFriendlySynchronizationContext" value="true" />

设置并且我的代码在本地工作正常我只在部署到azure时遇到问题。我正在使用Azure网站（https://www.windowsazure.com/en-us/home/scenarios/web-sites/），我的理解是它通常使用web.config？我还尝试通过Azure控制面板添加appsetting

将.ConfigureAwait(false);添加到我等待的方法中，但没有运气。

以下代码将抛出异常

public class TestController : Controller
    {
        public async Task<ActionResult> Index()
        {
            var httpResponse = await new HttpClient().GetAsync("http://www.google.com");
            FormsAuthentication.SetAuthCookie("test", true);
            return View();
        }
    }

任何人都知道如何让这个工作？

更新：

堆栈追踪：

[NullReferenceException: Object reference not set to an instance of an object.]
   System.Threading.Tasks.<>c__DisplayClass1c.<GetRethrowWithNoStackLossDelegate>b__1b(Task task) +91
   System.Threading.Tasks.TaskHelpersExtensions.ThrowIfFaulted(Task task) +15
   System.Web.Mvc.Async.TaskAsyncActionDescriptor.EndExecute(IAsyncResult asyncResult) +77
   System.Web.Mvc.Async.<>c__DisplayClass3f.<BeginInvokeAsynchronousActionMethod>b__3e(IAsyncResult asyncResult) +16
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +50
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) +29
   System.Web.Mvc.Async.<>c__DisplayClass39.<BeginInvokeActionMethodWithFilters>b__33() +59
   System.Web.Mvc.Async.<>c__DisplayClass4f.<InvokeActionMethodFilterAsynchronously>b__49() +240
   System.Web.Mvc.Async.<>c__DisplayClass37.<BeginInvokeActionMethodWithFilters>b__36(IAsyncResult asyncResult) +12
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +50
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) +31
   System.Web.Mvc.Async.<>c__DisplayClass2a.<BeginInvokeAction>b__20() +23
   System.Web.Mvc.Async.<>c__DisplayClass25.<BeginInvokeAction>b__22(IAsyncResult asyncResult) +128
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +50
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +26
   System.Web.Mvc.<>c__DisplayClass1d.<BeginExecuteCore>b__18(IAsyncResult asyncResult) +14
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +25
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +55
   System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +41
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +25
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +55
   System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +28
   System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +10
   System.Web.Mvc.<>c__DisplayClassb.<BeginProcessRequest>b__4(IAsyncResult asyncResult) +28
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +25
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +55
   System.Web.Mvc.<>c__DisplayClasse.<EndProcessRequest>b__d() +31
   System.Web.Mvc.SecurityUtil.<GetCallInAppTrustThunk>b__0(Action f) +7
   System.Web.Mvc.SecurityUtil.ProcessInApplicationTrust(Action action) +23
   System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +59
   System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9
   System.Web.CallHandlerExecutionStep.OnAsyncHandlerCompletion(IAsyncResult ar) +96

更新

如果手动设置Cookie，我发现它有效

FormsAuthenticationTicket ticket = new FormsAuthenticationTicket(1, "test", DateTime.Now, DateTime.Now.AddMinutes(30), true, null, FormsAuthentication.FormsCookiePath);
            string encTicket = FormsAuthentication.Encrypt(ticket);
            Response.Cookies.Add(new HttpCookie(FormsAuthentication.FormsCookieName, encTicket));

我不打算回答这个问题但是想知道为什么FormsAuthentication.SetAuthCookie抛出异常以及为什么它在Azure网站上表现不同

Answer 1

此问题并非特定于Azure - 在调用FormsAuthentication.SetAuthCookie之前调用await语句时，FormsAuthentication.SetAuthCookie方法将在异步操作中抛出空引用异常。

最简单的解决方案是使用以下内容：

        Response.Cookies.Add(FormsAuthentication.GetAuthCookie("user-1", true));

另一种方法是自己指定故障单创建：

        var ticket = new FormsAuthenticationTicket(
            2,
            "user-1",
            DateTime.Now,
            DateTime.Now.AddDays(2),
            true,
            String.Empty,
            "/");

        var encTicket = FormsAuthentication.Encrypt(ticket);

        Response.Cookies.Add(new HttpCookie(".AUTH", encTicket));

Answer 2

您可以根据自己的喜好更改此方式

public ActionResult Index()
{
    var t1 = Task.Run(() => HttpClient().GetAsync("http://www.google.com"));
    t1.Wait();
    FormsAuthentication.SetAuthCookie("test", true);
    return View();
}

这种方式对我有用，我从GlennMorton第一个答案中得到了想法

谢谢。

Answer 3

目前，Windows Azure网站不支持.NET 4.5。您需要将项目降级到.NET 4.0，这也意味着您需要重写代码以不使用异步。

您可以尝试bin部署应用程序所需的.NET 4.5程序集