JPA 2 Criteria API: why is isNull being ignored when in conjunction with equal?

Question

I have the following entity class (ID inherited from PersistentObjectSupport class):

@Entity
public class AmbulanceDeactivation extends PersistentObjectSupport implements Serializable {
    private static final long serialVersionUID = 1L;

    @Temporal(TemporalType.DATE) @NotNull
    private Date beginDate;

    @Temporal(TemporalType.DATE)
    private Date endDate;

    @Size(max = 250)
    private String reason;

    @ManyToOne @NotNull
    private Ambulance ambulance;

    /* Get/set methods, etc. */
}

If I do the following query using the Criteria API:

CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<AmbulanceDeactivation> cq = cb.createQuery(AmbulanceDeactivation.class);
Root<AmbulanceDeactivation> root = cq.from(AmbulanceDeactivation.class);
EntityType<AmbulanceDeactivation> model = root.getModel();
cq.where(cb.isNull(root.get(model.getSingularAttribute("endDate", Date.class))));
return em.createQuery(cq).getResultList();

I get the following SQL printed in the log:

FINE: SELECT ID, REASON, ENDDATE, UUID, BEGINDATE, VERSION, AMBULANCE_ID FROM AMBULANCEDEACTIVATION WHERE (ENDDATE IS NULL)

However, if I change the where() line in the previous code to this one:

cq.where(cb.isNull(root.get(model.getSingularAttribute("endDate", Date.class))),
    cb.equal(root.get(model.getSingularAttribute("ambulance", Ambulance.class)), ambulance));

I get the following SQL:

FINE: SELECT ID, REASON, ENDDATE, UUID, BEGINDATE, VERSION, AMBULANCE_ID FROM AMBULANCEDEACTIVATION WHERE (AMBULANCE_ID = ?)

That is, the isNull criterion is totally ignored. It is as if it wasn't even there (if I provide only the equal criterion to the where() method I get the same SQL printed).

Why is that? Is it a bug or am I missing something?

Answer 1

I tested your code and criteria query with EclipseLink (you're using EclipseLink, right?) and I reproduced the behavior: the isNull part is just ignored.

However, with Hibernate Entity Manager 3.5.1, the following query is generated:

select ambulanced0_.id as id7_, ambulanced0_.ambulance_id as ambulance5_7_, ambulanced0_.beginDate as beginDate7_, ambulanced0_.endDate as endDate7_, ambulanced0_.reason as reason7_ 
from AmbulanceDeactivation ambulanced0_ 
where (ambulanced0_.endDate is null) and ambulanced0_.ambulance_id=?

Which is the expected result. So I guess that we can assume this to be a bug of your JPA 2.0 provider.

Answer 2

I had the same strange behavior using Glassfish 3.0.1 which has embedded EclipseLink 2.0.

I have tried to change the embedded eclipselink libraries with the Glassfish 3.1.2 contained Eclipselink 2.3 library carefully. It solved the problem. So it is absolutely sure that the isNull check in equal condition is an eclipselink bug using criteriaBuilder.

I will upgrade soon our GlassFish environment in order to eliminate the problem.