Hibernate version: 3.0beta4

Hi,

i'm using Criteria to easily search some data. I'm setting firstResult and maxResults to paginate the data, but i'd like too have the 'count' of my request without this pagination.

For now i'm using this way :


Is there a better way ?

Hibernate3

Yes, that what i'm using.... but apparently i missed some documentation :-/

Have a look at http://javablogs.com/Jump.action?id=198498 i posted some examples for the new criteria api there. Also look at the source in org.hibernate.test.criteria

Thanks a lot, i missed Projections... great thing :)

An other question.. is there an easy way to duplicate a criteria (clone doesn't seems implemented according to javadoc) ?

I'd like build a criteria with restriction, then duplicate to have two criteria objects: one to get result list (with pagination) and one to project the rowCount.

Anybody have any ideas? I'm trying to do the same as magic. I have a detached criteria that defines the objects I want returned. Then I want to run several queries based on that defined criteria. One such query would be a count using projection. Another would be doing pagination. Unfortunately, when I set the projection to do the count (even though it seems done on seperate executable criteria), now the projection always applies to anything based on my original criteria. Is there any way around this?

So, reset to a different Projection ... ?

I can't figure out what other Projection I can set it to. Setting it to null or an empty projectionList() prevents it from knowing what class the criteria was supposed to be selecting (I get back Objects instead of the class I was expecting and hence get ClassCastExceptions).

Is there some sort of empty projection I'm missing that would be the equivalent of removing the count projection?

Thanks for you help.

I have posted some sample code to assist with solving this problem

http://forum.hibernate.org/viewtopic.ph ... 54#2234254

Yes - the default projection is the class that the criteria is created from in the first place.

I found this out the hard way.

i.e.

Criteria c = session.createCritera(Order.class);

Criteria c = c.createCriteria("customer");

Integer count = (Integer)c.setProjection(Projections.rowCount()).uniqueResult()

c.setProjection(null)

will return a List of Object[] {Order, Customer}

I guess you can set it back with

c.setProjection(Projections.someMethod(Order.class));

Cameron.

I posted some code at http://forum.hibernate.org/viewtopic.php?t=939781 which clones a detached criteria using serialization. I did this so I could copy the criteria and modify the copy for rowCount, setFirstResult, etc. at different times for pagination. I would be curious to know if this solution is crazier than any others.

:)

-gabe

Guys

You dont need to do the "double criteria" hacking.

After you get the row count, just do this (on the same Criteria):



.. and hey presto you can re-use the same criteria object.

HTH,
Ben

Actually, it's the other way arround:


setProjection sets the ResultTransformer to PROJECTION.

Uhmm, it seems a good idea to automate this: what about changing the setProjection to reset the result transformer back to default if invoked with null attribute ?

Does it make sense to use a PassThroughResultTransfomer with no projection ?

I was using a 2.x patched version of hibernate because I needed a count method.
I was adding a bunch of Criterion to a criteria, getting the list and getting the count. I thought it was going to be incorporated into version 3 (bug was closed on beta 3) but, I was wrong.
It used to be so simple:
List results = criteria.list();
long total = criteria.list();

Looking at forums related to this feature, it looks like the patch maintainer got fustrated and decided to just use his own custom code.

Now I'm trying to upgrade to Hibernate 3. And the code is looking worse. And type safety is reduced.
So now from what I get from the new docs:
long total = criteria.list();
becomes:
Integer count = (Integer)c.setProjection(Projections.rowCount()).uniqueResult();
int total = count.intValue();
Besides more code to do the same thing, we have to cast it to an Integer (lack of type safety) and the criteria object gets modified in the process. And from the debate in previous posts, its unclear how to restore the criteria to its unmodified previous state.

I understand the concern over interface bloat and that this was never an *official* feature but, it looks like it is a very useful and needed feature. This moving over to *Projections* looks like a lot of neat esoteric stuff that I'll never actually use. Most discussion around it seems to indicate that its being added in response to other vendors rather than the needs of the users.

I apologize for ranting and gettng a bit off topic. I just can't understand being offered a clean method and dropping it for a convoluted one. If we are going to cast all of our objects and have no type safety then we should just start using Perl.