c# - MVC 5 仍然需要 System.Web.Helpers 吗？

Question

按照指令 given here 将 MVC 4 应用程序升级到 MVC 5 之后，当我尝试登录时出现以下异常:

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

错误来源如下:

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);

这是程序集加载轨迹:

=== 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

这是堆栈跟踪:

[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

任何人都可以帮助确定这里的问题以及我如何解决它吗？

更新:

我在 NuGet 包管理器控制台 中运行了以下命令:

update-package -reinstall

运行后，对 System.Web.Helpers 的引用被添加回我的项目引用，尽管上面引用的指南说它已经更名并且应该被删除。在引用中返回 System.Web.Helpers 后，项目现在可以正常运行。所以现在的问题是:在更新到 MVC 5 之后是否仍然需要对 System.Web.Helpers 的引用，如果答案是“否”，那么为什么我的项目仍然需要这个引用？

Answer 1

不，一般不需要。

您的项目仍然需要引用，因为您正在使用 WebMatrix.WebData(特别是在您的代码段中，WebSecurity.Login)，它依赖于 System .Web.Helpers.