Problem with Eager Loading Nested Navigation Based on Abstract Entity (EF CTP5)

Question

I a portion of my EF model that looks like this:

Summary:

Answer 1

The new Query method might help you:

var location = context.Locations.SingleOrDefault();

context.Entry(location)
       .Collection(l => l.Posts)
       .Query()
       .OfType<Discussion>()
       .Load();

Repository Implementation:

We can add a new LoadProperty generic method to the Repository<T> class that leverages this new QUery method:

public void LoadProperty<TElement>(T entity, 
        Expression<Func<T, ICollection<TElement>>> navigationProperty,
        Expression<Func<TElement, bool>> predicate) where TElement : class
{
    _context.Set<T>().Attach(entity);

    _context.Entry(entity)         
            .Collection(navigationProperty)
            .Query()
            .Where(predicate)
            .Load();
}

Using the LoadProperty method:

Location location = _locationRepository.Find(1);
_locationRepository.LoadProperty(location, l => l.Posts, p => p is Discussion);