Retrieve emebedded or component using Hibernate Criteria api

Question

I have this class mapped as a entity, lets call it Person. Person has an embedded/component relation to Address. I am having trouble using a Criteria that would return Address objects. I have tried this:

Criteria.createCriteria(Address.class)

Which does not work. I guess I need to go through the entity but then I would need some kind of projection?

Criteria.createCriteria(Person.class).<<what goes here???>>

Suggestions?

Aeromarine

Answer 1

Component's lifetime is controlled by its owner; they are NOT considered associations. You therefore cannot retrieve component by itself from a query. You can, however, use it in criteria.

Assuming your "Address" class is mapped as "address" within "Person", you could do something like:

Criteria.createCriteria(Person.class)
 .add(Restrictions.eq("address.street", street));

Cylindroid

Ok, but how come I can do a HQL and retrieve the Address directly? Why does not the same apply for queries? – Aeromarine

Because HQL has capabilities that Criteria API does not. Now, if you really want to return your Address alone at any cost, you can create a projection list for Person-based criteria that would contain every property of Address (and nothing else) and apply AliasToBeanResultTransformer to a result. But this is a lot of headache and nothing to show for it; I'd select full Person instead and extract Address (if that's what you need) in java code. Or go with HQL. – Cylindroid

Answer 2

This is how one can retrieve or refer the property of embedded object in hibernate.

Criteria criteria = sessionFactory.getCurrentSession().createCriteria(
                Parent.class,"parent");
criteria.createAlias("embeddedObjectFieldName", "parent.embeddedObjectFieldName");

criteria.setProjection(Projections.projectionList()
                .add(Projections.groupProperty("parent.propertyOne"))
                .add(Projections.max("embeddedObjectFieldName.embeddedobjectproperty")));

Hope above clarifies

Kachine