EF过滤包括 - 许多子实体

Question

Having some issues with filtering child entities. I know that EF doesn't support filtered includes but I can't get any other alternative to work either.

var q = from sWithA in
                    (from s in db.Svs
                     where s.Env.UID.Equals(env)
                     select new
                     {
                         Svs= s,
                         Cons= from c in s.Cons
                                      where c.Apps.Any(a => a.AppT.Type.Equals(appT))
                                      select c
                     }).AsEnumerable()
                select sWithA.Svs;
List<Svs> svsList = q.ToList();

This actually generates a SQL query which returns the information I need, but the child entities aren't being attached to the parent.

svsList contains two Svs objects but the child collection (Cons) is empty.

Svs < many-to-many > Cons < many to one > Apps

Any ideas?

Answer 1

The relationship fixup trick that you apparently try to exploit doesn't work for many-to-many relationships, only for one-to-one and one-to-many relationships. For many-to-many relationships you have to fixup the navigation collections manually, for example like so:

List<Svs> svsList = (from s in db.Svs
                     where s.Env.UID.Equals(env)
                     select new
                     {
                         Svs = s,
                         Cons = from c in s.Cons
                                where c.Apps.Any(a => a.AppT.Type.Equals(appT))
                                select c
                     })
                     .AsEnumerable()
                     .Select(sWithA =>
                     {
                         sWithA.Svs.Cons = sWithA.Cons.ToList();
                         return sWithA.Svs;
                     })
                     .ToList(); 

Yes, it's ugly and looking at this code one really misses the filtered Include support.