Hi,

Currently I'm working on a project where I decided to use NHibernate for building the persistence layer, basically things are working quite well, and I think it is saving lots of work already :). Because NHibernate does not have native support for generic collections yet I’m using ayende's add-on as a workaround.

The problem is that while using ayende's add-on, the Session.Filter() on persistent collections doesn't seem to work (throwing an NHibernate.QueryException "the collection was unreferenced"). Probably this is because the real persistent collection is wrapped by an NHibernate.generics.EntitySet. Without ayende's add-on the filter is working perfectly.


The code I’m using is:
(NHibernateSessionManager is just an IHttpModule for controlling the hibernate session to make sure only one session is opened, and is properly closed)


Do I miss something? Or is there something I could do about this like implementing an specific interface or something?

Thanks in advance,
Patrick

I am also Looking at Something Similar but Getting some Exceptions. Could u plz let me Know if ur Solution Worked...


Thanking You

Prasanth

Hi Prasanth,

actually I didn't found a real satisfactory solution yet. I'm now doing queries using a Criteria object, which is also working well, but just not really what I was looking for.

Thus now using something like.

I posted the same problem before realising that you'd already started discussing the issue (http://forum.hibernate.org/viewtopic.php?t=954292).

It seems to be because Ayende's method involves wrapping the ISet and NHibernate doesn't know how to pass through the EntitySet<T> to get to it.

Exactly same bug with new NHibernate 1.2 beta 1. Very annoying.

You dont need Ayende's method with 1.2 beta. The built-in generic support works well.

I'm not using Ayende's NHibernate.Generics with 1.2b. Here is simple testcase, that fails with NHibernate.QueryException: the collection was unreferenced.

[TestMethod]
public void TestHibernateFiltering() {
Configuration cfg = new Configuration();
cfg.AddAssembly("Tests");
ISessionFactory factory = cfg.BuildSessionFactory();
ISession s = factory.OpenSession();
try {
IQuery q = s.CreateQuery("from BusinessEntity");
IList<BusinessEntity> list = q.List<BusinessEntity>();
Console.WriteLine(list.Count);
q = s.CreateFilter(list, "where this.IsArchived = false");
// this line fails
Console.WriteLine(q.List<BusinessEntity>().Count);
} finally {
s.Close();
}
}

// the class is trivial

public class BusinessEntity {
private Guid id;
private bool isArchived;

public BusinessEntity() {}

public virtual Guid ID {
get { return id; }
set { id= value; }
}

public virtual bool IsArchived {
get { return isArchived; }
set { isArchived = value; }
}
}

Stack trace is:
at NHibernate.Impl.SessionImpl.GetFilterTranslator(Object collection, String filter, QueryParameters parameters, Boolean scalar)
at NHibernate.Impl.SessionImpl.Filter(Object collection, String filter, QueryParameters parameters, IList results)
at NHibernate.Impl.SessionImpl.Filter[T](Object collection, String filter, QueryParameters parameters)
at NHibernate.Impl.QueryFilterImpl.List[T]()

Any help with it is really appreciated )

BTW: it fails even when using non-generic IQuery.List() method.

You can't use CreateFilter on arbitrary collections, only on those that belong to entities (persistent collections).

What are you talking about? I'm getting some entities to persistent collection, then filtering it. Or I've missed something? Please, explain.

Persistent collections are those collections that NHibernate tracks changes made to. They always belong to an entity, like LineItems collection of Order.

ILists and IList<T>'s returned from queries are not persistent collections.

Thanks, Sergey, that's explains all )