Resolving IDbSet<T> from AutoFac - entity-framework

Question

I would like to implement generic repository pattern with IDbSet<> interface of Entity Framework.
When i ask IDbSet<T> from Autofac, It should resolve IDbContext then call its Set<T> method to return the concrete type of IDbSet<T>
As an example, it should be doing something like this:
builder.Register<IDbSet<T>>(context => context.Resolve<IDbContext>().Set<T>());
How can i achive this with Autofac?

Answer 1

It seems based on this answer: https://stackoverflow.com/a/7997162/872395
that the only solution is to create a custom IRegistrationSource where you create the closed registrations:
public class DbSetRegistrationSource : IRegistrationSource
{
public bool IsAdapterForIndividualComponents
{
get { return true; }
}
public IEnumerable<IComponentRegistration> RegistrationsFor(
Service service,
Func<Service, IEnumerable<IComponentRegistration>> registrationAccessor)
{
var swt = service as IServiceWithType;
if (swt == null || !swt.ServiceType.IsGenericType)
yield break;
var def = swt.ServiceType.GetGenericTypeDefinition();
if (def != typeof(IDbSet<>))
yield break;
// if you have one `IDBContext` registeration you don't need the
// foreach over the registrationAccessor(dbContextServices)
yield return RegistrationBuilder.ForDelegate((c, p) =>
{
var dBContext = c.Resolve<IDBContext>();
var m = dBContext.GetType().GetMethod("Set", new Type[] {});
var method =
m.MakeGenericMethod(swt.ServiceType.GetGenericArguments());
return method.Invoke(dBContext, null);
})
.As(service)
.CreateRegistration();
}
}
The usage is very simple:
var containerBuilder = new ContainerBuilder();
containerBuilder.RegisterSource(new DbSetRegistrationSource());
containerBuilder.RegisterType<DbContext>().As<IDBContext>();
var container = containerBuilder.Build();