Hi,

I have two tables: OWNER (ownerId, name) and CAR (carId,ownerId,color,make,model).

Owner class looks like this: Owner{ownerId,name,cars}.
Car class looks like this: Car{carId,owner,color,make,model}.

As you can see, Car object has many-to-one relationship with Owner.

I create Criteria object like this:
Criteria c=session.createCriteria(Owner.class);
c.add(Expression.eq("name","John"));

And I add a filter on Car collection (name="colorFilter", param="color", condition="color=:color") like this:
session.enableFilter("colorFilter").setParameter("color","red");

As of now I have only one owner named John, so this query returns a single Owner object. John has 3 cars: red, green and blue, so Owner.cars for John contains 1 Car object (red one, according to the enabled filter).

So this works fine: Criteria are used to find top-level object (Owner), and filter is used to narrow the data in collection (Cars), since Criteria do not apply to collections.

Now I change my query like this:

Criteria c=session.createCriteria(Owner.class);
c.add(Expression.eq("name","John"));
c.createAlias("cars","crs");
c.add(Expression.eq("crs.make","Honda"));//one of John's cars is red Honda

And I set the color filter like this:
session.enableFilter("colorFilter").setParameter("color","black");

Now nothing comes back - no Owner objects are being returned at all. It's true that John has no black cars, but I would expect to get an Owner object back, with an empty collection of cars? After examining the SQL generated by Hibernate I saw that for some reason the filter condition was imported into the criteria SQL.
I'm guessing this is happening because criteria included alias to CAR table. What I don't understand is where does this dual approach come from? If Criteria is used to select the top-level object (Owner), and filters are used to control collections, then why are filters affecting the Criteria? Is this a bug of some sort?

I would appreciate it if someone could shed some light on this problem.
Thanks,

Bratek

No, that's the correct behaviour. To change the behaviour, you need to use an outer join. Do do this, you can either change your createAlias to createCriteria, or use setFetchMode(FetchMode.JOIN). (I think.. haven't tested that recently)

It's not a "dual approach". The query is asking for owners called John with black cars. It's not asking for owners called John, returning only black cars in their set. To change the question, you change the join mode.