@Override
public Room getRoomByRoomNumber(String roomNumber) {

    try {
        
        session = dataSourceFactory.getSessionFactory().openSession();
        beginTransactionIfAllowed(session);
        Query<Room> query = session.createQuery("from Room where number=:roomNumber", Room.class);
        query.setParameter("roomNumber", roomNumber);
        
        logging.setMessage("RoomDaoImpl -> fetching room by number "+roomNumber);
        return query.getSingleResult();

    } catch (NonUniqueResultException e) {
        logging.setMessage("RoomDaoImpl -> "+e.getLocalizedMessage());
        final InformationFrame frame = new InformationFrame();
        frame.setMessage("There is more than one room with this number!");
        frame.setVisible(true);
    }
    session.close();
    return null;
}
 

@Override
public Room getRoomByReservId(long id) {

    try {
        session = dataSourceFactory.getSessionFactory().openSession();
        beginTransactionIfAllowed(session);
        Query<Room> query = session.createQuery("from Room where ReservationId=:id", Room.class);
        query.setParameter("id", id);
        logging.setMessage("RoomDaoImpl -> fetching room by identity :"+id);
        return query.getSingleResult();

    } catch (NonUniqueResultException e) {
        session.getTransaction().rollback();
        logging.setMessage("RoomDaoImpl -> "+e.getLocalizedMessage());
        final InformationFrame frame = new InformationFrame();
        frame.setMessage(e.getLocalizedMessage());
        frame.setVisible(true);
    }
    session.close();
    return null;
}
 

public static DepartmentalInstructor findByPuidDepartmentId(String puid, Long deptId, org.hibernate.Session hibSession) {
	try {
	return (DepartmentalInstructor)hibSession.
		createQuery("select d from DepartmentalInstructor d where d.externalUniqueId=:puid and d.department.uniqueId=:deptId").
		setString("puid", puid).
		setLong("deptId",deptId.longValue()).
		setCacheable(true).
		setFlushMode(FlushMode.MANUAL).
		uniqueResult();
	} catch (NonUniqueResultException e) {
		Debug.warning("There are two or more instructors with puid "+puid+" for department "+deptId+" -- returning the first one.");
		return (DepartmentalInstructor)hibSession.
			createQuery("select d from DepartmentalInstructor d where d.externalUniqueId=:puid and d.department.uniqueId=:deptId").
			setString("puid", puid).
			setLong("deptId",deptId.longValue()).
			setCacheable(true).
			setFlushMode(FlushMode.MANUAL).
			list().get(0);
	}
}
 

public static <R> R uniqueElement(List<R> list) throws NonUniqueResultException {
	int size = list.size();
	if ( size == 0 ) {
		return null;
	}
	R first = list.get( 0 );
	for ( int i = 1; i < size; i++ ) {
		if ( list.get( i ) != first ) {
			throw new NonUniqueResultException( list.size() );
		}
	}
	return first;
}
 

static Object uniqueElement(List list) throws NonUniqueResultException {
	int size = list.size();
	if (size==0) return null;
	Object first = list.get(0);
	for ( int i=1; i<size; i++ ) {
		if ( list.get(i)!=first ) {
			throw new NonUniqueResultException( list.size() );
		}
	}
	return first;
}