How to return an object when using GROUP BY in HQL?

Question

I have a table of messages where where I have the columns ID , FROM_ID , TO_ID , DATE , and MESSAGE , with usual entity bean defined. I am trying to write a query where, given a recipient (aka TO_ID ) return the most recent message from each user (ie for each unique FROM_ID , return the record with the greatest DATE ).

The query I came up with is:

SELECT                           
   m.id, m.fromId, m.toId, m.message, max(m.sharedDate),
FROM                             
   Messages m                       
WHERE                            
   m.toId = ?           
GROUP BY                         
   m.fromId    

Now, I can take those columns back and populate a bean with them, but is there a way to have Hibernate do it?

Answer 1

wrap the selected columns in a constructor call:

select new WrapperBean(m.id, m.fromId, m.toId, m.message, max(m.sharedDate))...

where WrapperBean has a constructor with those args.