Autofac通用装饰器是复制组件

Question

I have found what I think may be a bug in Autofac, but I wanted to see if anybody had a possible solution or workaround so I can make this work.

Basically I have set up a generic decorator, which works fine. The problem is that as soon as I call BeginLifetimeScope() with a configuration delegate, it erroneously resolves multiple components of the same type. If I don't use a configuration delegate with BeginLifetimeScope() , then it works correctly. Unfortunately, I need to add additional dependencies to my child scope, so not using a configuration delegate is not an option.

Here is an example that demostrates the problem:

var builder = new ContainerBuilder();
builder.RegisterType<Dependency>()
    .Named<IDependency<object>>("service");
builder.RegisterGenericDecorator(
    typeof(Decorator<>), typeof(IDependency<>), "service", "decorated");
var container = builder.Build();

// Returns 1
var scope1 = container.BeginLifetimeScope();
Console.WriteLine(
    scope1.ResolveNamed<IEnumerable<IDependency<object>>>("decorated").Count());

// Returns 2 - notice the configAction doesn't even have to do anything
var scope2 = container.BeginLifetimeScope(r => { });
Console.WriteLine(
    scope2.ResolveNamed<IEnumerable<IDependency<object>>>("decorated").Count());

And here are my fake types:

interface IDependency<T> { }

class Dependency : IDependency<object> { }

class Decorator<T> : IDependency<T> {}

Any help would be greatly appreciated!

Answer 1

It does just seem like a bug. As a workaround, I ended up doing the following:

var param = new TypedParameter(typeof(IDecoratorDependency), new DecoratorDependency());
var decorated = scope.ResolveNamed<IEnumerable<IDependency<object>>>("decorated", param);

That was good enough for my use case. However, this method is inflexible because it only allows me to supply parameters to the root object, in this case Decorator<T> , but not any of its dependencies.