Question

What I am trying is to load all the A entities in the database together with B entities. The relationship between them is Every A entitiy has one B entitiy.

The project I am working on has a repository pattern and it has an All() method as below.

    public class EFRepository<T> : IRepository<T> where T : class, IObjectWithChangeTracker
        {
private IObjectSet<T> objectset;

        private IObjectSet<T> ObjectSet
        {
            get
            {
                if (objectset == null)
                {
                    objectset = UnitOfWork.Context.GetObjectSet<T>();
                }
                return objectset;
            }
        }
    public virtual IQueryable<T> All()
            {
                return ObjectSet.AsQueryable();
            }
    }

Is there any way that I can force B entities to eager load. What I’ve found is there there is no Include method on the IQueryable that returns from the All() method. I am happy to add a new member to repositroy so it can allow the client to use eager loading. But how can I do it?

Answer 1

You can create your own extension method which will allow you to use Include(path) against any IQueryable<T>:

public static IQueryable<TSource> Include<TSource>
  (this IQueryable<TSource> source, string path)
{
  var objectQuery = source as ObjectQuery<TSource>;
  if (objectQuery != null)
  {
    return objectQuery.Include(path);
  }
  return source;
}

There’s a full explanation on Julie Lerman’s blog: http://thedatafarm.com/blog/data-access/agile-entity-framework-4-repository-part-5-iobjectset/