Current implementation of query wrappers use the default getResultStream method implementation from Query interface, which invokes getResultList. It would be better if they implemented it and invoked getResultStream of the delegate query instance.

Note that EntityManager needs to be closed when stream processing is finished.

The setup contains an inheritance hierarchy on DAO objects described below. It ends up with an exception during deployment "Bean named 'datasetSourceDao' is expected to be of type 'cz.cvut.kbss.datasetdashboard.dao.DatasetSourceDao' but was actually of type 'com.sun.proxy.$Proxy38'.

When I flatten all DAOs into a single DAO, the transactions work.

I have a REST controller that autowires a service that autowires an instance of DatasetSourceDao. This DAO inherits from a base DAO (GenericDao being a generic DAO interface)
public abstract class BaseDao implements GenericDao {
@Autowired private EntityManager em;
...
@transactional("txManager")
public T find(URI uri) {
return em.find(type, uri);
}
...
}

and an inherited DAO

@repository
public class DatasetSourceDao extends BaseDao<dataset_source> {
@Autowired private EntityManager em;
public DatasetSourceDao() { super(dataset_source.class); }

@Transactional("txManager")
public void anotherMethod() {

...
}
...
}

Support for read-only transactions should be added, so that retrieve methods can be transactional instead of running outside of transaction and closing entity manager after each operation.