Max aggregate function not returning same type of argument

jbx1 · **Joined:** Mon May 19, 2008 1:59 pm **Posts:** 2

I am using Hibernate with the EntityManager and JPA syntax with Annotations.

I have the following named query:

Code:

SELECT NEW mt.com.jbx.EventEntry(p.sender, MAX(p.eventTime)) FROM PendingEvent p WHERE p.recipient.id=? GROUP BY p.sender ORDER BY MAX(p.eventTime) DESC

and the following entity:

Code:

...
import java.sql.Timestamp;

@Entity
@Table(name="pending_events")
public class PendingEvent implements Serializable 
{
...
    @Column(name="event_time", updatable=false, nullable=false)
    private Timestamp eventTime;
...
}

The eventTime is evidently a Timestamp, however when I try to do the max() aggregate function on it, and assign it to the constructor of the EventEntry class (which also takes a Timestamp) it is not accepting it.

Code:

import java.sql.Timestamp;

public class EventEntry 
{
    private String sender;
    private Timestamp lastEventTime;

    public EventEntry(String sender, Timestamp lastEventTime)
    {
        this.sender= sender;
        this.lastEventTime = lastEventTime;
    }
...
}

The Exception I am getting is:

Code:

java.lang.ExceptionInInitializerError
Caused by: javax.persistence.PersistenceException: [PersistenceUnit: EventsPU] Unable to build EntityManagerFactory
        at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:677)
        at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:126)
        at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:52)
        at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:34)
        at mt.com.jbx.EventHandler.<clinit>(EventHandler.java:33)
Caused by: org.hibernate.HibernateException: Errors in named queries: getEventSummary
        at org.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:365)
        at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1300)
        at org.hibernate.cfg.AnnotationConfiguration.buildSessionFactory(AnnotationConfiguration.java:859)
        at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:669)

For some reason, when I changed the lastEventTime to java.util.Date it seems to compile and work fine.

Any ideas why is this? It took me 2hrs to figure out what was happening because the error is so cryptic without any explanation.

cbredesen · **Posted:** Tue May 20, 2008 2:11 pm

Related:

http://opensource.atlassian.com/project ... e/HHH-1454

I don't have much to add, except that it seems odd to me as well...

cbredesen · **Posted:** Tue May 20, 2008 2:14 pm

And, Max's comment implies that you used the right workaround which is to use Date in your ctor. Timestamp on the db maps to Date in Java, I guess that's what he's saying. So it makes sense, kinda.

jbx1 · **Joined:** Mon May 19, 2008 1:59 pm **Posts:** 2

yes seems so...

its quite odd though, and the bug was flagged as rejected/duplicate

cbredesen · **Posted:** Tue May 20, 2008 3:10 pm

TimestampType does map to Date, though I'm not 100% sure that is what controls this, but I would think it is. You could then create a TimestampTimestampType that maps to java.sql.Timestamp. Though I'm confused b/c the javadoc states that TimestampType maps to either Date or Timestamp...

Code:

public Class getReturnedClass() {
   return java.util.Date.class;
}