Autofac WithKey Attribute not working as expected (multiple implementations) - autofac

Question

I tried to reconstruct the problem in LinqPad:
/*
“Named and Keyed Services”
http://autofac.readthedocs.org/en/latest/advanced/keyed-services.html
*/
const string A = "a";
const string B = "b";
const string MyApp = "MyApp";
void Main()
{
var builder = new ContainerBuilder();
builder
.RegisterType<MyClassA>()
.As<IMyInterface>()
.InstancePerLifetimeScope()
.Keyed<IMyInterface>(A);
builder
.RegisterType<MyClassB>()
.As<IMyInterface>()
.InstancePerLifetimeScope()
.Keyed<IMyInterface>(B);
builder
.RegisterType<MyAppDomain>()
.Named<MyAppDomain>(MyApp);
var container = builder.Build();
var instance = container.ResolveKeyed<IMyInterface>(A);
instance.AddTheNumbers().Dump();
var myApp = container.ResolveNamed<MyAppDomain>(MyApp);
myApp.Dump();
}
interface IMyInterface
{
int AddTheNumbers();
}
class MyClassA : IMyInterface
{
public int AddTheNumbers() { return 1 + 2; }
}
class MyClassB : IMyInterface
{
public int AddTheNumbers() { return 3 + 4; }
}
class MyAppDomain
{
public MyAppDomain([WithKey(A)]IMyInterface aInstance, [WithKey(B)]IMyInterface bInstance)
{
this.ANumber = aInstance.AddTheNumbers();
this.BNumber = bInstance.AddTheNumbers();
}
public int ANumber { get; private set; }
public int BNumber { get; private set; }
public override string ToString()
{
var sb = new StringBuilder();
sb.AppendFormat("ANumber: {0}", this.ANumber);
sb.AppendFormat(", BNumber: {0}", this.BNumber);
return sb.ToString();
}
}
when MyApp is “dumped” I am seeing ANumber: 7, BNumber: 7 which tells me that WithKey(A) is not returning the expected instance. What am I doing wrong here?

Answer 1

Looks like you forgot to register the consumers using WithAttributeFilter which is what allows this to work. Like:
builder.RegisterType<ArtDisplay>().As<IDisplay>().WithAttributeFilter();