Question

I have this registration in StructureMap

ObjectFactory.Initialize(x => {
    x.For<IPageModel>().UseSpecial(y => y.ConstructedBy( r => ((MvcHandler) HttpContext.Current.Handler).RequestContext.RouteData.GetCurrentModel<IPageModel>()));
});

And then I access this object in my constructor like this

public HomeController(IPageModel model) {}

Now I would like to register all concrete types that implements the interface IPageModel and when asked for I want to use the same For<> statement to get the correct instance.

It seems like i could use Scan together with my own convention to do this but I can’t figure out exactly how to do it.

This is some example code

x.Scan(scanner =>
{
    scanner.AssembliesFromApplicationBaseDirectory();
    scanner.Convention<MySpecialConvetion>();
});

public class MySpecialConvetion : IRegistrationConvention {
    public void Process(Type type, Registry registry) {
        if(type.IsAssignableFrom(typeof(IPageModel))) {
            registry.For<CONCRETE IMPLEMENTATION>().UseSpecial(y => y.ConstructedBy( r => ((MvcHandler) HttpContext.Current.Handler).RequestContext.RouteData.GetCurrentModel<CONCRETE IMPLEMENTATION>()));
        }
    }
}

Edit: It seems like I need to use the non-generic For, but how can I handle the construction my self using the non-generic For?

Answer 1

I got this working by creating a generic method definition, and used reflection to populate the types. Easier to show than explain:

    public class MySpecialConvetion : IRegistrationConvention
    {
        public static readonly MethodInfo RegisterMethod = typeof (MySpecialConvetion)
            .GetMethod("Register", BindingFlags.NonPublic | BindingFlags.Static)
            .GetGenericMethodDefinition();

        public void Process(Type type, Registry registry)
        {
            if (type.IsAssignableFrom(typeof (IPageModel)))
            {
                var specificRegisterMethod = RegisterMethod.MakeGenericMethod(new[] { type });
                specificRegisterMethod.Invoke(null, new object[] { registry });
            }
        }

        static private void Register<T>(Registry registry)
            where T : IPageModel
        {
            registry
                .For<T>()
                .UseSpecial(y => y.ConstructedBy(r => GetCurrentPageModel<T>()));
        }

        static private T GetCurrentPageModel<T>()
            where T : IPageModel
        {
            var handler = (MvcHandler) HttpContext.Current.Handler;
            if (handler == null)
                return default(T);
            return handler.RequestContext.RouteData.GetCurrentModel<T>();
        }
    }

I added an intermediate step and checked for a null handler since I didn’t have one in my site. But this should get you the missing piece you needed.