Description Michael OBrien 2007-07-09 16:58:10 EDT

When generating an entity from a table with automatic id generation for the primary key ID, the generated entity lacks the @GeneratedValue(strategy=GenerationType.IDENTITY) annotation.
The result of this is that the id returned to the persisted entity is not updated (via a select last_insert_id()) and defaults to 0.  Any use of this id by a child entity (via a foreign key mapping) will fail.

Workaround:
After generation, manually add @GeneratedValue annotation to all parent entities.

code:
public static void main(String[] args) {
		em.getTransaction().begin();
		aSite = dao.createSite("aSite");
		em.getTransaction().commit();
		System.out.println("Site id: " + aSite.getId());
}

DAO.java
	public Site createSite(String name) {
		Site aSite = new Site();
		aSite.setName(name);
		em.persist(aSite);		
		return aSite;		
	}


Schema:
create table job (ID integer(19) AUTO_INCREMENT,PRIMARY KEY (ID));

Generated Entity:
@Entity
public class Site implements Serializable {
	@Id
	private int id;
	private String name;
	.....

should be:

@Entity
public class Site implements Serializable {
	@Id @GeneratedValue(strategy=GenerationType.IDENTITY)
	private int id;
	private String name;
	.....

or we will get the following:

[TopLink Fine]: Connection(8140933)--INSERT INTO SITE (ID) VALUES (?)
	bind => [0]
Site id: 0

and an SQL error for any child of [Site] like Site<-Job where the fk is 0 instead of the generated Site id:

Internal Exception: com.mysql.jdbc.exceptions.MySQLIntegrityConstraintViolationException: Cannot add or update a child row: a foreign key constraint fails (`jpa/job`, CONSTRAINT `fk_site_job_id` FOREIGN KEY (`job_site`) REFERENCES `site` (`ID`))Error Code: 1452
Call:INSERT INTO JOB (ID, job_site) VALUES (?, ?)
	bind => [0, 0]
Query:InsertObjectQuery(com.ejb4.business.entity.Job@134ce4a)
	at oracle.toplink.essentials.exceptions.DatabaseException.sqlException(DatabaseException.java:295)

With the @GeneratedValue annotation (see ch4 p.88 of Pro EJB 3 JPA book by Mike Keith) we get back a populated ID field on the persisted Site:
[TopLink Fine]: Connection(3299256)--INSERT INTO SITE (NAME) VALUES (?)
	bind => [aSite]
[TopLink Fine]: Connection(3299256)--SELECT LAST_INSERT_ID()
Site id: 45

WindowsXPSP2
Dali 0.5.0.20060621 
This may be an underlying essentials generation problem if dali defers annotation generation to toplink - which i understant it does not.