英文:
Why cannot I resolve keyed registrations from lifetime scope?
问题
我正在尝试从生命周期范围解析带键的服务。以下代码呈现了问题：
public class Service1 : IService1 { }
public interface IService1 { }
public class Service2 : IService2
{
public Service2([KeyFilter("Test")] IService1 service1) { }
}
public class IService2 { }
public static class Program
{
public static void Main(string[] args)
{
var builder = new ContainerBuilder();
builder.RegisterType<Service1>().Named<IService1>("Test");
builder.RegisterType<Service2>().As<IService2>();
var container = builder.Build();
using (var scope = container.BeginLifetimeScope())
{
var service2 = scope.Resolve<IService2>();
}
}
}
我的意图是为特定的其他服务创建多个Service1注册。我需要使用范围，因为我已将DbContext注册为范围，服务需要它才能正常工作。
在启动演示代码后，我遇到了异常：
Autofac.Core.DependencyResolutionException: '在激活 ManagedConsoleSketchbook.Service2 时抛出了异常。'
内部异常
DependencyResolutionException: 无法使用可用的服务和参数调用类型 'ManagedConsoleSketchbook.Service2' 上找到的任何构造函数：
无法解析参数 'ManagedConsoleSketchbook.IService1 service1' 的构造函数 'Void .ctor(ManagedConsoleSketchbook.IService1)'。
我做错了什么吗？为什么无法从生命周期范围中解析具有名称/键的服务？
英文:
I'm trying to resolve keyed service from a lifetime scope. The following code presents the issue:
public class Service1 : IService1 { }
public interface IService1 { }
public class Service2 : IService2
{
public Service2([KeyFilter("Test")] IService1 service1) { }
}
public class IService2 { }
public static class Program
{
public static void Main(string[] args)
{
var builder = new ContainerBuilder();
builder.RegisterType<Service1>().Named<IService1>("Test");
builder.RegisterType<Service2>().As<IService2>();
var container = builder.Build();
using (var scope = container.BeginLifetimeScope())
{
var service2 = scope.Resolve<IService2>();
}
}
}
My intention is to create multiple Service1s registrations per specific other services. I need scopes, because I have registered DbContext as scoped and services needs it to work properly.
After starting the demo code, I'm getting the exception:
Autofac.Core.DepencencyResolutionException: 'An exception was thrown while activating ManagedConsoleSketchbook.Service2.'
Inner Exception
DependencyResolutionException: None of the constructors found on type 'ManagedConsoleSketchbook.Service2' can be invoked with the available services and parameters:
Cannot resolve parameter 'ManagedConsoleSketchbook.IService1 service1' of constructor 'Void .ctor(ManagedConsoleSketchbook.IService1)'.
Am I doing something wrong? Why cannot I resolve named/keyed service from a lifetime scope?
答案1
得分: 1
如果您阅读了 KeyFilterAttribute 上的文档，您会注意到您忘记将 .WithAttributeFiltering() 添加到 Service2 的注册中。属性过滤会影响性能，因此它是选择性的。
英文:
If you read the docs on the KeyFilterAttribute you'll notice you forgot to add .WithAttributeFiltering() to the Service2 registration. Attribute filtering is a perf hit so it's opt-in.
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