LINQ to NHibernate can't get to children's children

Question

I have entity A which has an IList of B called Bs and B has an IList of C called Cs.

I want to search for all A's which have at least 5 C's in them. So I went and wrote

using (var s = this._sessionFactory.OpenSession())
{
    IQueryable<A> q = s.Linq<A>();
    // some code...
    if (range.Min.HasValue)                    
        q = q.Where(a => a.Bs.Sum(b => b.Cs.Count) >= range.Min.Value);
    // some code...
    return q.Select(b=>b).ToArray();
 }

However upon executing the code (and having Min specified in the range variable) I get the following exception :

NHibernate.QueryException : could not resolve property: Cs of: A

Why does it look for the B's property on A? The mappings seem to be right though :

The (Fluent) mapping on A says :

//...
HasMany(a => a.Bs)
 .Table("Bs")
 .KeyColumn("IdA")
 .Cascade.AllDeleteOrphan()
 .Inverse()
 .Not.LazyLoad();
//...

and on the mapping on B says :

//...
HasMany(b => b.Cs)
 .Table("Cs")
 .KeyColumn("IdB")
 .Cascade.AllDeleteOrphan()
 .Inverse()
 .Not.LazyLoad();
References(b => b.A, "IdA")
 .Not.LazyLoad();
//...

finally on the mapping on C :

References(c => c.B, "IdB").Not.LazyLoad();

Answer 1

You can't do it with LINQ to NHibernate 2.x