~/Resolving a list of type registrations from Autofac
26 June 2014
I needed to get all types that implemented a given interface that were registered with Autofac. Not a set of factories, that would be as simple as this:
class Consumer
{
public Consumer(IEnumerable<Func<IFoo>> fooFactories)
{
// ...
}
}
What I really need is something like Consumer(IEnumerable<Type> fooTypes) where the types are everything implementing IFoo, but of course Autofac can’t resolve that.
Inspired by this StackOverflow answer, here’s an extension method that does what I need:
public static class LifetimeScopeExtensions
{
public static IEnumerable<Type> GetImplementingTypes<T>(this ILifetimeScope scope)
{
return scope.ComponentRegistry
.RegistrationsFor(new TypedService(typeof (T)))
.Select(x => x.Activator)
.OfType<ReflectionActivator>()
.Select(x => x.LimitType);
}
}
To use it my consumer just takes an ILifetimeScope dependency:
public Consumer(ILifetimeScope scope)
{
var fooTypes = scope.GetImplementingTypes<IFoo>();
}
Note that I needed to register the types both as the base type IFoo (for the implementing type resolution) and as self, so I could later resolve using scope.Resolve(fooType). My registration looks like this:
builder.RegisterAssemblyTypes(typeof (IFoo).Assembly)
.Where(t => t.IsAssignableTo<IFoo>())
.Where(t => !t.IsAbstract)
.As<IFoo>()
.AsSelf()
.InstancePerDependency();
