How to retrieve not a domain bean but some of its properties

stephaneeybert · **Joined:** Mon Apr 16, 2007 8:10 am **Posts:** 246

Hi,

I'm trying to retrieve some properties of a domain bean.

I have an HQL query with a projection as in:

Code:

   public List findCountByBrowser() {
      Query query = getSession().createQuery("select count(*) as count, visitorBrowser from StatisticsVisit group by visitorBrowser");
      return query.list();
   }

Is the List the appropriate type for it ? The compiler would like me to add a SuppressWarning directive as it lacks generic types.

How to iterate the results ? Do I need a convenience data bean with these two properties count and visitorBrowser ?

Or is there any better way to go..?

Thanks !

stephaneeybert · **Joined:** Mon Apr 16, 2007 8:10 am **Posts:** 246

Anyone ?

stephaneeybert · **Joined:** Mon Apr 16, 2007 8:10 am **Posts:** 246

No one ?

Is my issue not properly laid out or hard to understand ?

ngomo · **Joined:** Tue Sep 14, 2010 4:29 pm **Posts:** 16

Hi stephaneeybert,

in fact this is not well documented (or I haven't found the right spot yet). Judging from the behavior of SQL Scalar Queries described here: http://docs.jboss.org/hibernate/core/3.6/reference/en-US/html/querysql.html#d0e17378 I'd guess that the items in the result list are of type Object[]. Provided I am not wrong, I'd write your method as follows:

Code:

   public List<Object[]> findCountByBrowser() {
      Query query = getSession().createQuery("select count(*) as count, visitorBrowser from StatisticsVisit group by visitorBrowser");
      // We will have to do an unchecked cast here to bridge from non generic list()-method to a generic return type. We
      // can suppress warnings with annotation.
      @SuppressWarnings("unchecked")
      final List<Object[]> resultList = (List<Object[]) query.list();
      return resultList;
   }

If I guessed right, you will be fine. If I not, you will get a ClassCastException and my apologies ;-))

Cheers ngomo

stephaneeybert · **Joined:** Mon Apr 16, 2007 8:10 am **Posts:** 246

Hello !

Thanks, it was the way to go.

It's funny because my integration test, which was already coded against the Dao method, worked fine.

This is how my Dao method looks like:

Code:

   @SuppressWarnings("unchecked")
   @Override
   public List<Object[]> findCountsByBrowser() {
      Query query = getSession().createQuery("select count(*) as count, visitorBrowser from StatisticsVisit group by visitorBrowser order by visitorBrowser");
      final List<Object[]> resultList = (List<Object[]>) query.list();
      return resultList;
   }

I was almost there, I only needed to add the Object[] type to the collection.

Now the question is, is this the way to go in Hibernate when encountering this issue ?

Maybe some day some one who stumbles by will tell us :-)

Thanks for your hint anyway.