c# - Autofac 无法在运行时解析来自某些程序集的类型，在调试器中工作

Question

在我的解决方案中，我有更多的程序集。其中一些包含一个 Autofac 模块，其中包含来自程序集的注册。我在启动后立即将所有注册连接在一起。到目前为止一切正常，我通过构造函数注入(inject)创建了依赖项，Autofac 帮助我解决了依赖项。

(在这个项目中，我在控制台应用程序中托管 SignalR 和 WebApi 功能。我也使用 OWIN。)

在添加 WebApi 并使用 DI 创建我的第一个 Controller 后，我遇到了一个问题。在 MyController 的构造函数中我依赖 MyInterface .当我尝试在我的 Controller 上调用任何方法时，我得到了普通的

None of the constructors found with 'Autofac.Core.Activators.Reflection.DefaultConstructorFinder' on type 'MyController' can be invoked with the available services and parameters: Cannot resolve parameter 'MyInterface myInt' of constructor 'Void .ctor(MyInterface)'.

异常。我注意到了什么:

• 如果我替换MyInterface与另一个组件中的另一个一起加载 Controller 。
• MyInterface可以在我的代码中的另一个地方解决(在另一个程序集中)

我继续进行一些调试。我试图在我的 OWIN 启动类中的启动时解决一些类。我现在看到的是

• 我无法解析 MyAssembly1 中的任何类型, MyAssembly2
• 我可以解析 MyAssembly3 中的所有类型, MyAssembly4
• container.Resolve<MyInterface> 从代码中抛出异常
• container.Resolve<MyInterface>如果我在调试期间通过 Visual Studio 中的监 window 口解析它，则返回已解析的类
• 我在container.ComponentRegistry.Registrations 中看到所有 注册

你能告诉我，我做错了什么吗？

更新

我尽量提供所有必要的信息，请让我知道，如果我仍然忘记了什么。

这是 AssemblyA 中的 Autofac 模块定义

public class AutofacModuleConfig : Module, IAutofacModuleConfig
{
    protected override void Load(ContainerBuilder builder)
    {
        builder.RegisterType<MyWorkingImplementation>().As<IMyWorkingInterface>();

        base.Load(builder);
    }

这是 AssemblyB 中的 Autofac 模块定义

public class AutofacModuleConfig : Module, IAutofacModuleConfig
{
    protected override void Load(ContainerBuilder builder)
    {
        builder.RegisterType<MyNotWorkingImplementation>().As<IMyNotWorkingInterface>();

        base.Load(builder);
    }
}

在设置 WebHost 的程序集中有 Controller 的注册(与以前的结构相同)

builder.RegisterApiControllers(System.Reflection.Assembly.GetExecutingAssembly());

这就是我在应用程序启动时注册东西的方式

private void RegisterModuleDependencies()
{
    var builder = new ContainerBuilder();
    builder.RegisterType<Core.Logger.Log4NetLogger>().As<ILogger>();

    var moduleConfigs = GetModuleConfigurations();
    foreach (var module in moduleConfigs)
        builder.RegisterModule(module);

    container = builder.Build();
}

private List<Autofac.Module> GetModuleConfigurations()
{
    var type = typeof(IAutofacModuleConfig);
    var types = AppDomain.CurrentDomain.GetAssemblies()
        .SelectMany(s => s.GetTypes())
        .Where(p => type.IsAssignableFrom(p) && p.GetConstructor(Type.EmptyTypes) != null);
    return types.Select(t => (Autofac.Module)Activator.CreateInstance(t)).ToList();
}

这是SignalR和WebApi的启动方法

private void Startup(IAppBuilder app)
{
    IDependencyResolver resolver = new AutofacDependencyResolver(container);
    GlobalHost.DependencyResolver = resolver;

    ...

    ConfigureOAuth(app, resolver.Resolve<IAuthorizationService>());

    app.UseCors(CorsOptions.AllowAll);
    app.MapSignalR(new HubConfiguration
    {
        Resolver = resolver,
        EnableDetailedErrors = true,
        EnableJavaScriptProxies = false
    });

    //Host WebApi
    HttpConfiguration webApiConfiguration = new HttpConfiguration();
    webApiConfiguration.MapHttpAttributeRoutes();
    webApiConfiguration.Routes.MapHttpRoute("DefaultWebApi", "api/{controller}/{id}", new { id = RouteParameter.Optional });
    webApiConfiguration.Services.Add(typeof(System.Web.Http.ExceptionHandling.IExceptionLogger), new WebApiExceptionLogger());
    webApiConfiguration.DependencyResolver = new AutofacWebApiDependencyResolver(container);
    app.UseWebApi(webApiConfiguration);
}

出于测试目的，我包含了常见示例中使用的 ValuesController。使用默认构造函数，它自然可以正常工作。如果我用 IMyWorkingInterface 添加构造函数然后，正如其名称所暗示的那样，它可以完美运行。但是，如果我将构造函数包含在 IMyNotWorkingInterface 中而不是工作的然后我得到了异常。

public class ValuesController : ApiController
{
    //private readonly TestNamespaceInAssemblyB.IMyNotWorkingInterface notWorkingInstance;

    //public ValuesController(TestNamespaceInAssemblyB.IMyNotWorkingInterface notWorkingInstance)
    //{
    //  this.notWorkingInstance = notWorkingInstance;
    //}

    private readonly TestNamespaceInAssemblyA.IMyWorkingInterface workingInstance;

    public ValuesController(TestNamespaceInAssemblyA.IMyWorkingInterface workingInstance)
    {
        this.workingInstance = workingInstance;
    }

想在加IMyNotWorkingInterface的时候再点一下作为另一个程序集(比方说 AssemblyC)的依赖项，然后它会被 Autofac 正确解析。

在调试器中我看到了注册 MyNotWorkingImplementation在监 window 口中。更重要的是，我什至可以从调试器中解决它，正如您在图像上看到的那样。

更新2

我为 Autofac 事件创建了事件处理程序，这里的日志显示了当我尝试注入(inject) IMyNotWorkingInterface 时发生的情况。

2017-01-08 13:32:36.920753 | [0x00002acc] | DEBUG | Core        - WebHost                                   | AGENT  | Chile lifetime scope started
2017-01-08 13:32:36.934754 | [0x00002acc] | DEBUG | Core        - WebHost                                   | AGENT  | Resolve operation started
2017-01-08 13:32:36.936754 | [0x00002acc] | DEBUG | Core        - WebHost                                   | AGENT  | Instance lookup is beginning for Activator = ValuesController (DelegateActivator), Services = [API.Agent.Web.Controllers.ValuesController], Lifetime = Autofac.Core.Lifetime.CurrentScopeLifetime, Sharing = None, Ownership = ExternallyOwned
2017-01-08 13:32:36.938754 | [0x00002acc] | DEBUG | Core        - WebHost                                   | AGENT  | Instance lookup is beginning for Activator = ValuesController (ReflectionActivator), Services = [API.Agent.Web.Controllers.ValuesController], Lifetime = Autofac.Core.Lifetime.CurrentScopeLifetime, Sharing = None, Ownership = OwnedByLifetimeScope
2017-01-08 13:32:36.939754 | [0x00002acc] | DEBUG | Core        - AutofacModuleConfig                       | AGENT  | Resolve for was requested by Activator = ValuesController (ReflectionActivator), Services = [API.Agent.Web.Controllers.ValuesController], Lifetime = Autofac.Core.Lifetime.CurrentScopeLifetime, Sharing = None, Ownership = OwnedByLifetimeScope
2017-01-08 13:32:36.966757 | [0x00002acc] | DEBUG | Core        - WebHost                                   | AGENT  | Resolve operation finished
2017-01-08 13:32:36.967757 | [0x00002acc] | ERROR | Core        - WebHost                                   | AGENT  | 
Autofac.Core.DependencyResolutionException: None of the constructors found with 'Autofac.Core.Activators.Reflection.DefaultConstructorFinder' on type 'API.Agent.Web.Controllers.ValuesController' can be invoked with the available services and parameters:
Cannot resolve parameter 'TestNamespaceInAssemblyB.IMyNotWorkingInterface notWorkingInstance' of constructor 'Void .ctor(TestNamespaceInAssemblyB.IMyNotWorkingInterface)'.
   at Autofac.Core.Activators.Reflection.ReflectionActivator.ActivateInstance(IComponentContext context, IEnumerable`1 parameters)
   at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)
   at Autofac.Core.Resolving.InstanceLookup.Execute()
   at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable`1 parameters)
   at Autofac.Core.Resolving.InstanceLookup.ResolveComponent(IComponentRegistration registration, IEnumerable`1 parameters)
   at Autofac.Core.Registration.ExternalRegistrySource.<>c__DisplayClass8.<RegistrationsFor>b__3(IComponentContext c, IEnumerable`1 p)
   at Autofac.Core.Activators.Delegate.DelegateActivator.ActivateInstance(IComponentContext context, IEnumerable`1 parameters)
   at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)
   at Autofac.Core.Resolving.InstanceLookup.Execute()
   at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable`1 parameters)
   at Autofac.Core.Resolving.ResolveOperation.Execute(IComponentRegistration registration, IEnumerable`1 parameters)
2017-01-08 13:32:38.085869 | [0x000029c4] | DEBUG | Core        - WebHost                                   | AGENT  | Child lifetime scope closed

知道在哪里可以将一些调试代码粘贴到 Autofac 中吗？ (对了，我用的是Autofac 3.5.2)

Answer 1

确保注册您的 Controller 。您需要为 autofac 包含 WebApi 特定的 nuget 包，并在启动时从您的容器构建器调用以下方法:

RegisterApiControllers(Assembly.GetExecutingAssembly());