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我正在尝试使用 autofac 管理我的 WCF 客户端的注册。

我需要解决Func<MachineEndpoint, IFooService>，所以我使用以下方法注册了服务：

builder.Register((c, p) => FooService(c, p.TypedAs<MachineEndpoint>())).UseWcfSafeRelease()

FooService 在哪里：

private IJobService FooService(IComponentContext c, MachineEndpoint endpoint) {...}

这工作正常，但我想添加一个装饰器来处理某些安全错误，所以我尝试了以下方法：

builder.Register((c, p) => FooService(c, p.TypedAs<MachineEndpoint>())).UseWcfSafeRelease().Named<IFooService>("simple foo service");
builder.RegisterDecorator<IFooService>((c, p, inner) => Wrap(inner, p.TypedAs<MachineEndpoint>(), c.Resolve<CertificateLookupCache>()), "simple foo service");

但我得到一个 DependecyResolutionException：

Autofac.Core.DependencyResolutionException: An exception was thrown while executing a resolve operation. See the InnerException for details. ---> System.InvalidOperationException: Sequence contains no elements
   at System.Linq.Enumerable.First[TSource](IEnumerable`1 source)
   at MyModule.<Load>b__4(IComponentContext c, IEnumerable`1 p) in MyModule.cs:line 30 (the first line above)
   at Autofac.Builder.RegistrationBuilder.<>c__DisplayClass1`1.<ForDelegate>b__0(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.Features.LightweightAdapters.LightweightAdapterRegistrationSource.<>c__DisplayClass3.<RegistrationsFor>b__1(IComponentContext c, IEnumerable`1 p)
   at Autofac.Builder.RegistrationBuilder.<>c__DisplayClass1`1.<ForDelegate>b__0(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)
   --- End of inner exception stack trace ---

Server stack trace:
   at Autofac.Core.Resolving.ResolveOperation.Execute(IComponentRegistration registration, IEnumerable`1 parameters)
   at Autofac.Core.Lifetime.LifetimeScope.ResolveComponent(IComponentRegistration registration, IEnumerable`1 parameters)
   at lambda_method(Closure , MachineEndpoint )

如何注册这些函数，以便将 MachinEndpoint 参数同时传递给 WCF 客户端对象和装饰器？

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1 回答 1

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问题是由您的参数使用引起的：p.TypedAs<MachineEndpoint>()因为目前 Autofac 有一个限制，即在创建装饰对象RegisterDecorator时不传递参数。inner

因此，当它尝试创建inner时(c, p) => FooService(c, p.TypedAs<MachineEndpoint>())将(IEnumerable<Parameter> p)是空的，因此您会遇到异常。

你基本上可以做两件事：

您可以尝试以不再使用的方式重新组织您的代码p.TypedAs<MachineEndpoint>()。

或者

因为IFooService无论如何您的 WCF 服务没有多个实现，您可以通过“手动”注册您的装饰器：

builder.Register((c, p) => FooService(c, p.TypedAs<MachineEndpoint>()))
       .UseWcfSafeRelease()
       .Named<IFooService>("simple foo service");
builder.Register<IFooService>((c, p) => 
     Wrap(c.ResolveNamed<IFooService>("simple foo service",
          TypedParameter.From(p.TypedAs<MachineEndpoint>())),
          p.TypedAs<MachineEndpoint>(),
          c.Resolve<CertificateLookupCache>()));
于 2013-03-18T21:39:54.990 回答