Autofac 无法解析 class

Question

我正在为后端构建一个使用 ASP.Net MVC 的应用程序。 Autofac 被用于依赖注入。几个 components/classes 注册为 InstancePerRequest。 Entity Framework 上下文和工作单元（只是一个调用 context.SaveChanges() 的包装器）被注册为 InstancePerLifetimeScope。示例代码：

builder.RegisterAssemblyTypes(Assembly.GetAssembly(typeof(DomainModule)))
    .Where(t => t.IsClosedTypeOf(typeof(IFooService<>)))
    .AsImplementedInterfaces()
    .AsClosedTypesOf(typeof(IFoo<>))
    .InstancePerRequest();

builder.RegisterType<FooContext>()
    .AsSelf()
    .As<IObjectContextAdapter>()
    .InstancePerLifetimeScope();

builder.RegisterType<UnitOfWork>()
    .AsImplementedInterfaces()
    .AsSelf()
    .InstancePerLifetimeScope();

使用显式范围从容器解析 class 会引发以下异常：

{"No scope with a Tag matching 'AutofacWebRequest' is visible from the scopein 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."}

触发上述异常的代码：

using (var scope = _lifetimeScope.BeginLifetimeScope())
{
    var authOrchestration = scope.Resolve<IAuthOrchestration>();
    apiClient = authOrchestration.GetApiClient(context.ClientId);
}

请注意，IAuthOrchestration 并未注册 InstancePerRequest 之类的内容，因此应该默认为 InstancePerDependency。

几个小时以来，我一直在努力思考这个问题。我读过 these two articles. From what I've read, I guess the exception is being thrown due to the scopes that do not match (as described here)。如果有人能够解释为什么我会收到此错误，我将不胜感激。

非常感谢。

Answer 1

IAuthOrchestration 对注册为 InstancePerHttpRequest 的 IFoo 具有间接依赖性。要（直接或间接）解决 IFoo 你必须使用 request ILifetimeScope

您创建了一个 ILifetimeScope 而不是 RequestLifetimeScope。要创建这样的 ILifetimeScope，您可以使用 MatchingScopeLifetimeTags.RequestLifetimeScope` 标签。

using (var scope = _lifetimeScope
                    .BeginLifetimeScope(MatchingScopeLifetimeTags.RequestLifetimeScopeTag))
{
    var authOrchestration = scope.Resolve<IAuthOrchestration>();
    apiClient = authOrchestration.GetApiClient(context.ClientId);                
}

Autofac 无法解析 class

Autofac cannot resolve class

c#

asp.net-mvc

entity-framework

autofac