如何将Autofac的DependencyResolutionException在ASP.NET的Owin、SignalR和集线器MVC中实现长尾词？

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在配置ASP.NET MVC 5.2、SignalR 2.1、MS Owin（Katana）3.0以及Autofac 3.5时，以下是一个简洁的示例：

csharp// 配置Autofacvar builder=new ContainerBuilder();

// 注册依赖builder.RegisterType().As().InstancePerRequest();

// 解析器builder.RegisterAssemblyTypes(typeof(Program).Assembly).Where(t=> t.IsClass && t.Name.EndsWith(Controller)) .AsSelf() .InstancePerRequest();

// 使用ILifetimeScopevar container=builder.Build();var scope=container.BeginLifetimeScope();var controller=scope.Resolve();

注意：Autofac解析器的配置可能不复杂，但确保正确使用。`ILifetimeScope`对于依赖注入是必需的，如果不可见，可能是配置或引用错误。

什么应该是 Asp.net Mvc 5.2,SignalR 2.1,MS Owin(Katana)3.0的Autofac 3.5配置？注册Autofac解析器的方法是否不那么复杂(现在有两个)？或者为什么ILifetimeScope对我的集线器不可见？

例外：

Autofac.Core.DependencyResolutionException: An exception was thrown
while invoking the constructor ‘Void .ctor(Autofac.ILifetimeScope)’ on
type ‘OperatorHub’. —>

No scope with a Tag matching
‘AutofacWebRequest’ is visible from the scope in which the instance
was requested. This generally indicates that a component registered as
per-HTTP request is being requested by a SingleInstance() component
(or a similar scenario.) Under the web integration always request
dependencies from the DependencyResolver.Current or
ILifetimeScopeProvider.RequestLifetime, never from the container
itself. (See inner exception for details.) —>

Autofac.Core.DependencyResolutionException: No scope with a Tag
matching ‘AutofacWebRequest’ is visible from the scope in which the
instance was requested. This generally indicates that a component
registered as per-HTTP request is being requested by a
SingleInstance() component (or a similar scenario.) Under the web
integration always request dependencies from the
DependencyResolver.Current or ILifetimeScopeProvider.RequestLifetime,
never from the container itself.

在我的OwinStartup中(见autofac + mvc owin和autofac + signalr in owin)：

public void Configuration(IAppBuilder app) { var builder = new ContainerBuilder(); // ... registration. There is .InstancePerRequest() and .SingleInstance() Autofac.Integration.Mvc.RegistrationExtensions.RegisterControllers(builder,typeof(MvcApplication).Assembly); Autofac.Integration.SignalR.RegistrationExtensions.RegisterHubs(builder, Assembly.GetExecutingAssembly()); var container = builder.Build(); // 1st resolver DependencyResolver.SetResolver(new AutofacDependencyResolver(container)); app.UseAutofacMiddleware(container); app.UseAutofacMvc(); // yet the 2nd resolver! app.MapSignalR(new HubConfiguration { Resolver = new Autofac.Integration.SignalR.AutofacDependencyResolver(container) }); }

枢纽：

public class OperatorHub : Hub { public OperatorHub(ILifetimeScope hubLifetimeScope) { hubLifetimeScope.BeginLifetimeScope(); // ... // HERE IT FALLS. The IMyService relates to MyDbContext (see below) var myservice = hubLifetimeScope.Resolve<IMyService>(); } }

UPDATE

破坏组件注册(EF上下文：

builder.RegisterType<MyDbContext>().AsSelf().As<DbContext>().InstancePerRequest("OwinLifetimeScope");

简而言之,错误是MyDbContext不在’root’生命周期范围内,该范围被传递给OperatorHub构造函数.

更新2

在@TravisIllig的帮助下,解决方案是使用.InstancePerLifetimeScope()注册MyDbContext服务,并在集线器中创建一个.将在asp mvc中为http请求创建另一个生命周期范围.在Sharing Dependencies Across Apps Without Requests创建帮助.

集线器也不应该处理给定的作用域,因为它是在第二次运行时导致ObjectDisposedException的根作用域.

There is an FAQ on handling this exact exception on the Autofac doc site.问题源于您将InstancePerRequest与SignalR结合使用的事实,其中, also per the documentation：

Due to SignalR internals, there is no support in SignalR for per-request lifetime dependencies.

您似乎已经查看了the Autofac SignalR docs,因为我看到您注入了一个生命周期范围来帮助您管理实例生命周期,但这并没有为您提供每个请求的生命周期范围,它只是为您提供了一个集线器生命周期范围.我可能会建议重新访问该文档以进行复习.

The FAQ I mentioned与SignalR集成文档一起,应该为您的应用指出正确的解决方案.许多人只是简单地将他们的注册从InstancePerRequest切换到InstancePerLifetimeScope,但我强烈建议您在跳转到该决定之前阅读常见问题并查看您的选项.它可能是正确的选择,但可能不是 – 这取决于您的应用程序在内部的工作方式.