Eager loading in Entity Framework fails on complex query

Question

The following query fails to load the tables when I execute it:

IEnumerable<Bookmark> tempBookmarks = ListBookmarksByUserID(userID);
IEnumerable<CandidateWithBookmarks> results = (from c in _internshipEntities.CandidateSet
                                            .Include("education")
                                            .Include("progress")
                                            .Include("contacts")
                                            .Include("availability")
                                            .Include("hosttypes")
                                            .Include("hostsizes")
                                            .Include("hostcapacities")
                                            .Include("hoststates")
                                            .Include("users")
                       join b in tempBookmarks on c.ID equals b.candidates.ID
                       select new CandidateWithBookmarks()
                                  {CandidateObject = c, BookmarkObject = b});
return results;

I have found some articles related to the problem, namely Alex James' article "How to make Include really Include". The solution comes with one caveat:

For this to work your final select must be entities, i.e. select post rather than select new {…}

Which is obviously an issue for the above block of code. Are there any other known work-arounds for this issue that won't break eager loading?

Answer 1

I think I solved this but it might only work for this specific instance, by moving the includes after the join, the query appears to work:

IEnumerable<CandidateWithBookmarks> results = (
    from b in tempBookmarks
    join c in _internshipEntities.CandidateSet
                                 .Include("education")
                                 .Include("progress")
                                 .Include("contacts")
                                 .Include("availability")
                                 .Include("hosttypes")
                                 .Include("hostsizes")
                                 .Include("hostcapacities")
                                 .Include("hoststates")
                                 .Include("users")
    on b.candidates.ID equals c.ID
    select new CandidateWithBookmarks(){CandidateObject = c, BookmarkObject = b});

Edit: Another query I have similar to this requires an outer join as well, which creates some issues since it then matters what you join to what, unlike this example, but it's still doable.