Hi,

Should eager loading of a collection within an object cause the object to be loaded multiple times?

Example: Should this query return multiple cars if there is only 1 car in the database (that has 2 doors)?
Dim criteria As ICriteria = SessionHandler.CurrentSession.CreateCriteria(GetType(Car)).Add(Expression.Eq("CarId", 1).SetFetchMode("Doors", NHibernate.FetchMode.Eager).List(Of Car)()


In my query, it returns a list of 2 cars (the same cars)...am I misunderstanding the use of fetchmodes? Shouldn't the fetch modes just fetch the Door objects of the Car? Is there an other way to do this?

Regards

Hmm...I found this: .SetResultTransformer(CriteriaUtil.DistinctRootEntity)
and find it pretty awkward that it should be used...
What if I need fetchmodes in collections of collections, will NHibernate also load duplicate objects? Eg, will there be 4 door objects in the car if each door has 2 windows (and the windows of the doors are eagerly loaded)?

It's by design, have a look here:

http://www.hibernate.org/117.html#A12

and

http://jira.nhibernate.org/browse/NH-748

It's a faq for hibernate, but it's the same in nhibernate. Btw. the duplicates are all references to the same object instance. Hibernate does not instantiate the object more than ones.

Thanks. Nice response.

"It should be also obvious why resultset row-based "limit" operations, such as setFirstResult(5) and setMaxResults(10) do not work with these kind of eager fetch queries. If you limit the resultset to a certain number of rows, you cut off data randomly. One day Hibernate might be smart enough to know that if you call setFirstResult() or setMaxResults() it should not use a join, but a second SQL SELECT. "

Do you know if nhibernate already supports the "firstresult" and "maxresults" with eager loading at this moment?

Sorry, I don't know ...