I've created an HQL statement to get a specific class and some of its one to many amd many to one properties. I also have filters in my "where" clause to only get some of the elements in its one to many collections.

I discovered that NHibernate disregrads these filters and gives me all the elements in the collections!!

My NHibernate session persists for the entire life of the asp.net session. Perhaps NHibernate is getting the values from the cache without realizing that I am doing a filter in my HQL and do not want all the values from the cache.

This is by design, NHibernate won't load a persistent collection with less elements than it truly has. Try using ISession.CreateFilter instead.

This is not good design. HQL should always return what you expect it to, wether it has a where clause or not. I shouldn't have to use a different API if I want to filter.

Suppose I start out with an HQL statement that does not have filters and some time later I need to add a filter to it. Now I have to rewrite my code to use a different API. This is not good design.

Well, I myself believe the design is right, useful to prevent strange bugs later. If you have a Customer, then Customer.Orders are all Customer's orders, no matter where you got it from and what query you used. If you only want some of the orders, you filter the collection.

Another reason why we won't change it is that Hibernate does things this way.

Think of objects, not database rows.

If you have "FROM Customer", you are selecting a customer, the whole customer. Even if it is "customers with an order over $300" you are going to get all the orders when you reference customer.Orders.

And like sergey said, Hibernate does it, so NHibernate does it.

you could do: "SELECT c, o FROM Customer c INNER JOIN c.Orders o WHERE o.Amount > $300" and get back a list of 2 element arrays, a customer and a matching order. Not sure if this is what you want.