Custom model binder for a property

Question

I have the following controller action:

[HttpPost]
public ViewResult DoSomething(MyModel model)
{
    // do something
    return View();
}

Answer 1

override BindProperty and if the property is "PropertyB" bind the property with my custom binder

That's a good solution, though instead of checking "is PropertyB" you better check for your own custom attributes that define property-level binders, like

[PropertyBinder(typeof(PropertyBBinder))]
public IList PropertyB {get; set;}

You can see an example of BindProperty override here.