Is there any built in mechanism to do a HQL query and return a List of partially populated object instances?

For example, say if I have a Person class with firstName, lastName, dob, sex, height attributes.

There may be a case where I only want to return the firstName and lastName fields for every Person, i.e. at this point in time I am not interested in retrieving Person instances with every attribute populated.

If I issue a query like this:



...if I understand this correctly this will return to me a List of Object arrays, one Object array for each row returned, where each Object in the array represents the selected data from the query.

I think overall this makes sense, as HQL queries objects, not actual database columns right? If I select an attribute on my Person class which is say of a PersonName type, then I would retrieve PersonName instances right?

So my original question, is there any way in which I can retrieve partially populated instances from a query?

Thanks,
Kevin Hooke

you can use "select new Person(person.name, person.firstname) from Person person" probably, if you have an appropriate constructor.

Hi,

In most cases the performance hit (in terms of the database) for accessing the tuple for multiple columns as opposed to a single column in the same table is negligible. One of the exceptions is when you have (binary/character) large objects in the db which you need to stream.

On the vm side the picture is slightly different: are you concerned about creating large java objects which may consume a larger amount of memory?

A pattern that may be of interest to you is the Lightweight class: http://hibernate.org/41.html

Otherwise gloeglm's suggestion may be a simpler solution.

Regards