greedy loading of associations

[michalbali]

Hi,

Nice piece of work!

Are you planning to support greedy loading of associations? (e.g. in the demo if I load some Address revision, the Person set is lazy loaded when I access it.)

Thank you.
Regards,
Michal

[adamw]

Hello,

that's true, all associations (except for the not-owning-side of one-to-one) are now loaded lazily.

Maybe I'll just check the value of the "fetch" attribute of the annotations and load lazily or not. You think that'd be sufficient?

Adam

[michalbali]

That sounds good to me. If I remember correctly, that's how hibernate does it. By default, it loads associations lazily, but you can override it - per property or per class.

Thanks,
Michal

[awhitford]

Just to clarify, the default fetchType varies depending on the type of association:

http://java.sun.com/javaee/5/docs/api/javax/persistence/OneToOne.html#fetch() - EAGER
http://java.sun.com/javaee/5/docs/api/javax/persistence/OneToMany.html#fetch() - LAZY
http://java.sun.com/javaee/5/docs/api/javax/persistence/ManyToOne.html#fetch() - EAGER
http://java.sun.com/javaee/5/docs/api/javax/persistence/ManyToMany.html#fetch() - LAZY

[michalbali]

Yes, that makes sense.

Thanks,
Michal

[scottr0829]

Sorry to bring this older thread back to life.

Adam, did you ever get a chance to implement the "checking of the fetch type" into the association load?

I ask because I have a many-to-one relationship that I eagerly load and I keep getting an error on the entity envers finds because the id of that object is null (optional is false too). I trace through the code and see the variables as being fetched lazily. I verified there is a valid id in the db - it just doesn't seem to be fetching the object.

[adamw]

Hello,

no, eager loading isn't yet implemented, but it shouldn't cause errors like "id is null". Can you maybe post more details or create a testcase and file a JIRA bug?

--
Adam

[scottr0829]

Hi Adam,

Thanks for your response and help.

The code for the method is below:

@SuppressWarnings("unchecked")
 public <T extends Request> String getLatestChanges(Class<T> type, T request)
 {
 LOG.trace("Starting getLatestChanges...");

 StringBuilder changes = new StringBuilder();

 if (request == null || request.getId() == null)
 {
 throw new IllegalArgumentException("invalid request passed in");
 }

 request = em.find(type, request.getId());

 Integer revNumber = (Integer) getVersionsReader().createQuery().forRevisionsOfEntity(type, false, true)
 .add(VersionsRestrictions.idEq(request.getId()))
 .addProjection(RevisionProperty.max())
 //.add(VersionsRestrictions.eq("revision_type", RevisionType.MOD))
 .getSingleResult();

 LOG.debug("Going to get revision #"+revNumber);

 T prevReq = (T) getVersionsReader().createQuery().forEntitiesAtRevision(type, revNumber)
 .add(VersionsRestrictions.idEq(request.getId()))
 .getSingleResult();

 if (prevReq == null)
 {
 LOG.debug("No changes registered.");
 }
 else
 {
 if (request instanceof ClockRequest)
 {
 changes.append(getClockChanges((ClockRequest) request, (ClockRequest) prevReq));
 }
 else if (request instanceof StudioRequest)
 {
 changes.append(getStudioChanges((StudioRequest) request, (StudioRequest) prevReq));
 }
 else
 {
 changes.append(getEventChanges((EventRequest) request, (EventRequest) prevReq));
 }

 }


 LOG.trace("Returning from getLatestChanges...");

 return changes.toString();
 }

When I run this, everything comes back fine from Envers in the prevReq object except for the eventType attribute - it stays null and the debugger says the variable handler is JavassistLazyInitializer (I found this after putting a breakpoint at the if (prevReq == null) and looking at the object). Looking at the Request object, eventType is of type EventType and is supposed to be eagerly fetched, as well as optional=false. Since there is no eventType with id null (it is required), we are getting a
javax.persistence.EntityNotFoundException: Unable to find EventType with id null error.

Any ideas why envers is not pulling back the event_type_id field from the db? I have confirmed it exists in the record.

[scottr0829]

I want to add that the eventType attribute in Request has a ManyToOne relationship and has a join column defined. There are never any issues saving and reading the current version, only the versions returned via the envers query.

[adamw]

Hello,

I tried to reproduce your issue but can't. I have a many-to-one relationship, I persist two entities and then query for the many side, and read the related reference - and it's read properly. Maybe you can create a testcase and post a JIRA bug? Or am I not reproducing the case correctly?

--
Adam