WebApi 2、OWIN 和 AutoFac - 更改 HttpContextBase 依赖项答案

【问题标题】：WebApi 2, OWIN and AutoFac - change HttpContextBase dependencyWebApi 2、OWIN 和 AutoFac - 更改 HttpContextBase 依赖项
【发布时间】：2015-09-12 08:59:08
【问题描述】：

最近我决定要集成测试我的 WebApi 2 应用程序。我决定将我的应用程序转换为符合 OWIN 标准。我已经包含了所有的 NuGet 包并将其与 AutoFac 中间件等连接起来。

但是，当我尝试在示例程序的 Main 方法中使用 HttpClient 测试应用程序时，出现错误：

{
  "Message":"An error has occurred.",
  "ExceptionMessage":"An error occurred when trying to create a controller of type 'DinnerListController'. Make sure that the controller has a parameterless public constructor.",
  "ExceptionType":"System.InvalidOperationException",
  "StackTrace":"   at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)\r\n   at System.Web.Http.Controllers.HttpControllerDescriptor.CreateController(HttpRequestMessage request)\r\n   at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__1.MoveNext()",
  "InnerException":{
    "Message":"An error has occurred.",
    "ExceptionMessage":"An exception was thrown while executing a resolve operation. See the InnerException for details. ---> Value cannot be null.\r\nParameter name: httpContext (See inner exception for details.)",
    "ExceptionType":"Autofac.Core.DependencyResolutionException",
    "StackTrace":"   at Autofac.Core.Resolving.ResolveOperation.Execute(IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Lifetime.LifetimeScope.ResolveComponent(IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.ResolutionExtensions.TryResolveService(IComponentContext context, Service service, IEnumerable`1 parameters, Object& instance)\r\n   at Autofac.ResolutionExtensions.ResolveOptionalService(IComponentContext context, Service service, IEnumerable`1 parameters)\r\n   at Autofac.Integration.WebApi.AutofacWebApiDependencyScope.GetService(Type serviceType)\r\n   at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.GetInstanceOrActivator(HttpRequestMessage request, Type controllerType, Func`1& activator)\r\n   at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)",
    "InnerException":{
      "Message":"An error has occurred.",
      "ExceptionMessage":"Value cannot be null.\r\nParameter name: httpContext",
      "ExceptionType":"System.ArgumentNullException",
      "StackTrace":"   at System.Web.HttpContextWrapper..ctor(HttpContext httpContext)\r\n   at Autofac.Integration.Mvc.AutofacWebTypesModule.<Load>b__0(IComponentContext c)\r\n   at Autofac.RegistrationExtensions.<>c__DisplayClass10`1.<Register>b__f(IComponentContext c, IEnumerable`1 p)\r\n   at Autofac.Builder.RegistrationBuilder.<>c__DisplayClass1`1.<ForDelegate>b__0(IComponentContext c, IEnumerable`1 p)\r\n   at Autofac.Core.Activators.Delegate.DelegateActivator.ActivateInstance(IComponentContext context, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.<Execute>b__0()\r\n   at Autofac.Core.Lifetime.LifetimeScope.GetOrCreateAndShare(Guid id, Func`1 creator)\r\n   at Autofac.Core.Resolving.InstanceLookup.Execute()\r\n   at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.ResolveComponent(IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Registration.ExternalRegistrySource.<>c__DisplayClass8.<RegistrationsFor>b__3(IComponentContext c, IEnumerable`1 p)\r\n   at Autofac.Core.Activators.Delegate.DelegateActivator.ActivateInstance(IComponentContext context, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.Execute()\r\n   at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.ResolveComponent(IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Activators.Reflection.AutowiringParameter.<>c__DisplayClass2.<CanSupplyValue>b__0()\r\n   at Autofac.Core.Activators.Reflection.ConstructorParameterBinding.Instantiate()\r\n   at Autofac.Core.Activators.Reflection.ReflectionActivator.ActivateInstance(IComponentContext context, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.<Execute>b__0()\r\n   at Autofac.Core.Lifetime.LifetimeScope.GetOrCreateAndShare(Guid id, Func`1 creator)\r\n   at Autofac.Core.Resolving.InstanceLookup.Execute()\r\n   at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.ResolveComponent(IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Registration.ExternalRegistrySource.<>c__DisplayClass8.<RegistrationsFor>b__3(IComponentContext c, IEnumerable`1 p)\r\n   at Autofac.Core.Activators.Delegate.DelegateActivator.ActivateInstance(IComponentContext context, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.Execute()\r\n   at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.ResolveComponent(IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Activators.Reflection.AutowiringParameter.<>c__DisplayClass2.<CanSupplyValue>b__0()\r\n   at Autofac.Core.Activators.Reflection.ConstructorParameterBinding.Instantiate()\r\n   at Autofac.Core.Activators.Reflection.ReflectionActivator.ActivateInstance(IComponentContext context, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.<Execute>b__0()\r\n   at Autofac.Core.Lifetime.LifetimeScope.GetOrCreateAndShare(Guid id, Func`1 creator)\r\n   at Autofac.Core.Resolving.InstanceLookup.Execute()\r\n   at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.ResolveComponent(IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Registration.ExternalRegistrySource.<>c__DisplayClass8.<RegistrationsFor>b__3(IComponentContext c, IEnumerable`1 p)\r\n   at Autofac.Core.Activators.Delegate.DelegateActivator.ActivateInstance(IComponentContext context, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.Execute()\r\n   at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.ResolveOperation.Execute(IComponentRegistration registration, IEnumerable`1 parameters)"
    }
  }
}

我隔离了原因：这是我的服务依赖于 HttpContextBase 来存储和从 cookie 中提取内容：

public CookieUserService(HttpContextBase httpContext)

并且 AutoFac 无法初始化此类。当我尝试另一个实现时，没有HttpContextBase，依赖它起作用了。

所以问题是：有没有办法在使用 OWIN 时访问 cookie，所以我可以重构服务并摆脱 HttContextBase（和 Web.dll）的依赖关系？

【问题讨论】：

能贴出方法代码吗？
你可以传入你自己的界面而不是HttpContextBase。
尝试 GetOwinContext: msdn.microsoft.com/en-us/library/dn270723(v=vs.113).aspx 并使用该上下文而不是 HttpContext 因为 OWIN 的目的是消除对主机的依赖 (HttpContext)
@KhanhTO：感谢您的链接！看起来这将是要走的路——我实际上将使用 IOwinContext 作为服务中的依赖项。第一个测试表明我可以简单地将IOwinContext 添加为依赖项，看起来 AutoFac 实际上足够聪明，可以自动解决该依赖项。
@jjczopek：如果您不向 AutoFac 注册任何内容，这怎么可能？它应该由 OWIN 框架注入。

标签： c# httprequest asp.net-web-api2 owin autofac

【解决方案1】：

切换到 OWIN 时，对 System.Web 等的所有依赖项都变得无效，因为它们将应用程序与 IIS 托管环境紧密耦合。因此 AutoFac 无法将 HttpContextBase 作为依赖项注入到我的服务中，因为它无法即时。

为了克服这个问题，服务应该依赖于 OWIN 特定的接口，而不是像 HttpContextBase 这样使用 System.Web 依赖项，这些接口提供应用程序和托管环境之间的抽象。

在我的具体情况下，我将服务更改为依赖 IOwinContext，如下所示：

public OwinCookieUserService(IOwinContext owinContext)
{
    if (owinContext == null) throw new ArgumentNullException(nameof(owinContext));  
    _owinContext = owinContext;
}

添加两个额外的 NuGet 包后：

Autofac.Owin
Autofac.WebApi2.Owin

我能够在我的 Startup 课程中将 AutoFac 和 OWIN 粘合在一起：

public class Startup
{
   public void Configuration(IAppBuilder appBuilder)
   {
       var httpConfiguration = new HttpConfiguration();
       ...
       AutoFacConfig.ConfigureAutoFac(httpConfiguration);
       appBuilder.UseAutofacMiddleware(AutoFacConfig.Container);
       appBuilder.UseAutofacWebApi(httpConfiguration);
       appBuilder.UseWebApi(httpConfiguration);
   }
}

在我的 AutoFac 映射中，我有以下例程来定义我的服务依赖项：

....
    builder.RegisterType<OwinCookieUserService>().AsImplementedInterfaces().InstancePerLifetimeScope();
....

基本上就是这样！我不必专门为 OWIN 接口和类设置映射，它就可以工作。我希望这会对你们中的一些人有所帮助。

【讨论】：