EntityModelBinder.cs

public class EntityModelBinder : IModelBinder
{
    private static readonly TypeConverter _converter = TypeDescriptor.GetConverter(typeof (Guid));


    public bool Matches(Type type)
    {
        return type.CanBeCastTo<DomainEntity>();
    }

    public void Bind(Type type, object instance, IBindingContext context)
    {
        throw new NotSupportedException();
    }

    public object Bind(Type type, IBindingContext context)
    {
        var rawId = context.Service<IRequestData>().Value("Id");
        var id = (Guid)_converter.ConvertFrom(rawId);

        return context.Service<IRepository>().Find(type, id) ?? Activator.CreateInstance(type);
    }
}