Hello,

I'm using Christian Bauer's example of a GenericDAO as a base class for my own DAOs. If you're not familiar with it, here's the relevant code:



I'm looking to add a similar method that returns results as a Map<ID,T> instead of a List<T>. At first I thought projections would be the answer, something like the following:



However, this solution requires a projection that returns the entity itself, and not aggregate information or a specific property on that entity. I can't find a ResultTransformer to do this for me nor have I entered a Google query that has provided illumination.

Any suggestions?

Thanks,

Joel

Well, I'd still like to know how to use Projections to return the entity itself, but until then, here's a solution using the session object:

Set a ResultTransformer on the critera like this:


criteria.setResultTransformer(Transformers.aliasToBean(YourEntity.class));

List<YourEntity> list = criteria.list();

You had to give your projections aliases for this to work. If you don't then you'll get back a null for property in your entity.


@SuppressWarnings("unchecked")
public void test() throws Exception {
Session session = HibernateUtil.getSessionFactory().openSession();
Transaction transaction = session.beginTransaction();
Criteria criteria = session.createCriteria(Queue.class);
ProjectionList projections = Projections.projectionList().add(Projections.property("queueId"), "queueId").add(
Projections.property("configurationXml"), "configurationXml");
criteria.setProjection(projections);

criteria.setResultTransformer(Transformers.aliasToBean(Queue.class));

List<Queue> list = criteria.list();

for (Queue queue : list) {
log.debug("whee:" + queue.getQueueId() + " " + queue.getConfigurationXml());
}

transaction.commit();
session.close();
}


And my Queue Entity class has six columns in the database and I did this test to get back only two. You can use this same code and take off the alias and see you'll get nothing back but nulls. It uses the alias to find the setter method that matches the pattern *setAlias*.