MVC 5仍需要System.Web.Helpers嗎？

Question

按照此處給出的說明將MVC 4應用程序升級到MVC 5后，嘗試登錄時出現以下異常：

Could not load file or assembly 'System.Web.Helpers, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'

錯誤的來源如下：

Line 77:         public ActionResult Login(RegisterLoginModel model, string returnUrl)
Line 78:         {
Line 79:             if (ModelState.IsValid && WebSecurity.Login(model.Login.UserName, model.Login.Password, persistCookie: model.Login.RememberMe))
Line 80:             {
Line 81:                 return Redirect(returnUrl);

這是程序集負載跟蹤：

=== Pre-bind state information ===
LOG: DisplayName = System.Web.Helpers, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35
 (Fully-specified)
LOG: Appbase = file:///D:/Users/Bruce/Documents/Projects/Pace/CourseChooser/trunk/CourseChooser.Web/
LOG: Initial PrivatePath = D:\Users\Bruce\Documents\Projects\Pace\CourseChooser\trunk\CourseChooser.Web\bin
Calling assembly : WebMatrix.WebData, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35.
===
LOG: This bind starts in default load context.
LOG: Using application configuration file: D:\Users\Bruce\Documents\Projects\Pace\CourseChooser\trunk\CourseChooser.Web\web.config
LOG: Using host configuration file: D:\Users\Bruce\Documents\IISExpress\config\aspnet.config
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\v4.0.30319\config\machine.config.
LOG: Post-policy reference: System.Web.Helpers, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35

這是堆棧跟蹤：

[FileNotFoundException: Could not load file or assembly 'System.Web.Helpers, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.]
   WebMatrix.WebData.SimpleMembershipProvider.CheckPassword(IDatabase db, Int32 userId, String password) +0
   WebMatrix.WebData.SimpleMembershipProvider.ValidateUser(String username, String password) +171
   System.Web.Security.Membership.ValidateUser(String username, String password) +26
   WebMatrix.WebData.WebSecurity.Login(String userName, String password, Boolean persistCookie) +42
   Selector.Controllers.AccountController.Login(RegisterLoginModel model, String returnUrl) in D:\Users\Bruce\Documents\Projects\Pace\CourseChooser\trunk\CourseChooser.Web\Controllers\Account\AccountController.cs:79
   lambda_method(Closure , ControllerBase , Object[] ) +146
   System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) +30
   System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +197
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +46
   System.Web.Mvc.Async.ActionInvocation.InvokeSynchronousActionMethod() +37
   System.Web.Mvc.Async.AsyncControllerActionInvoker.<BeginInvokeSynchronousActionMethod>b__39(IAsyncResult asyncResult, ActionInvocation innerInvokeState) +24
   System.Web.Mvc.Async.WrappedAsyncResult`2.CallEndDelegate(IAsyncResult asyncResult) +43
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +58
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +68
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) +34
   System.Web.Mvc.Async.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3d() +69
   System.Web.Mvc.Async.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() +230
   System.Web.Mvc.Async.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() +230
   System.Web.Mvc.Async.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() +230
   System.Web.Mvc.Async.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() +230
   System.Web.Mvc.Async.<>c__DisplayClass33.<BeginInvokeActionMethodWithFilters>b__32(IAsyncResult asyncResult) +27
   System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +27
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +58
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +68
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) +34
   System.Web.Mvc.Async.<>c__DisplayClass2b.<BeginInvokeAction>b__1c() +42
   System.Web.Mvc.Async.<>c__DisplayClass21.<BeginInvokeAction>b__1e(IAsyncResult asyncResult) +124
   System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +27
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +58
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +30
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +29
   System.Web.Mvc.Controller.<BeginExecuteCore>b__1d(IAsyncResult asyncResult, ExecuteCoreState innerState) +27
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +48
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +58
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +30
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +21
   System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +32
   System.Web.Mvc.Controller.<BeginExecute>b__15(IAsyncResult asyncResult, Controller controller) +26
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +40
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +58
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +30
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +21
   System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +29
   System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +24
   System.Web.Mvc.MvcHandler.<BeginProcessRequest>b__5(IAsyncResult asyncResult, ProcessRequestState innerState) +27
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +48
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +58
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +30
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +21
   System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +29
   System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +23
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9744373
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155

誰能在這里幫助您確定問題以及我該如何解決？

更新：

我在NuGet Package Manager Console運行以下命令：

update-package -reinstall

運行此命令后，將對System.Web.Helpers的引用添加回我的項目引用中，盡管以上引用的指南指出已對其進行了更名並應將其刪除。 有了System.Web.Helpers的引用，該項目現在可以正確運行。 因此，現在的問題是：在更新到MVC 5之后是否仍然需要引用System.Web.Helpers ，並且如果回答為“否”，那么為什么我的項目仍需要該引用？

Answer 1

不，通常不需要。

您的項目仍然需要引用，因為您正在使用WebMatrix.WebData （特別是在代碼段WebSecurity.Login ），它依賴於System.Web.Helpers 。