[hibernate-issues] [Hibernate-JIRA] Created: (EJB-362) JPA Max/Min aggregate functions do not return same state-field type when argument is a java.sql.Timestamp

[josef (JIRA)]

JPA Max/Min aggregate functions do not return same state-field type when argument is a java.sql.Timestamp
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                 Key: EJB-362
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/EJB-362
             Project: Hibernate Entity Manager
          Issue Type: Bug
          Components: EntityManager
    Affects Versions: 3.3.2.GA
         Environment: JDK 1.6, Postgres 8.2, JDBC 4
            Reporter: josef


According the JPQL specification, MAX and MIN aggregate functions should return the type of the state-field to which they are applied. However, if one tries to query MAX or MIN on a java.sql.Timestamp entity field and tries to populate a class which expects a java.sql.Timestamp in the constructor with the result of MAX or MIN, Hibernate fails with javax.persistence.PersistenceException. The result of MAX or MIN in this case are being java.util.Date instead.

The error result in type mismatch should ideally also be more helpful, because it is very difficult to understand what and where the problem is, unless you know about it beforehand.

Here is an example Entity, with the aggregate class and query, together with the exception that occurs:


... 
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; 
... 
}

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; 
    } 
... 
}

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



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)




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