EntityHome + nested persist = FK constraint violation

[damianharvey]

Hi,

I have an Entity USER that can be in many GROUPs. This relationship is held in the USERGROUP entity. I have a page where a new User can be created and their groups selected.

When I go to persist these using the following code I get a Foreign Key Constraint Violation from mySQL as the USER doesn't yet exist in the database.

public String add() {

 //Persist the user
 String status = userHome.persist();
 log.info("Persisted User");

 userHome.getEntityManager().flush();
 log.info("Flushed User");

 //Process the groups
 Iterator groupIter = groups.iterator();
 while(groupIter.hasNext()) {
 Groups group = (Groups)groupIter.next();

 //Use the EntityHome object to persist
 userGroupListHome.create();
 userGroupListHome.getInstance().setUser(userHome.getInstance());
 userGroupListHome.getInstance().setGroups(group);

 userGroupListHome.persist();
 }
}

My understanding was that the flush() would actually force the transient object to be saved to the database. If I look in the DB it isn't there.

Would appreciate any advice as this has driven me nuts once before.

Thanks,

Damian.

[damianharvey]

Additionally Hibernate is logging the insert:

[STDOUT] Hibernate: insert into USER (...etc etc

[damianharvey]

This was caused by my Entities not having their auto-incrementing IDs annotated with @GeneratedValue.

It makes sense in hindsight, but the symptoms were odd. I'm still not sure why the flush() didn't work.

I had changed my method to have the FlushModeType.MANUAL but the entityManager.flush() was still not hitting the database. The flush() method must have an active transaction otherwise it will be ignored. If using a POJO what is the reccommended way to get this working? Is the Seam Managed Transaction sufficient for the flush (ie. so it's not ignored)?