Question

I’ve been trying to work out why this query asking for a manager and his or her team only returns the first entry for the Team collection. Apparently, it’s because I had FirstOrDefault at the end of the query. I was under the impression the FirstOrDefault would apply to the query as a whole, but it seems it’s being applied to the Team collection as well.

Original query (shows only 1st member in Team):

  session.Query<IEmployee>()
                .Where(p => p.PersonalNumber == PersonalNumber)
                .Fetch(p => p.Team)
                .Fetch(p => p.Manager)
                .FirstOrDefault();

New query which returns full team:

  session.Query<IEmployee>()
                .Where(p => p.PersonalNumber == PersonalNumber)
                .Fetch(p => p.Team)
                .Fetch(p => p.Manager)
                .ToList().FirstOrDefault();

What would be the correct way to formulate this query? My need for a workaround implies I’m not doing this properly.

Background – mappings:

This is a basic hierarchical relationship with Manager being an IEmployee and Team being an IList of IEmployee.

References(x => x.Manager).Column("ManagerId");
HasMany(x => x.Team)
                .AsList(index => index.Column("TeamIndex"))
                .KeyColumn("ManagerId");

Answer 1

I have been struggling with the same problem. For me, this occurred when upgrading from NH 3.1 -> 3.3. The problem is that with Linq, NHibernate 3.3 generates a SQL query that has a “Top(1)” statement in it, effectively killing the “Fetch”-part of the query. I solved it by switching from Linq to QueryOver. I believe this will work:

  session.QueryOver<IEmployee>()
                .Where(p => p.PersonalNumber == PersonalNumber)
                .Fetch(p => p.Team)
                .Fetch(p => p.Manager)
                .SingleOrDefault();