Auto flushing

[denis-karpov]

Hello.

I have conversation. And at the end of this conversation i need to apply or reject changes. But after each post the flushing occurs. And all temporary changes persist to database.

How can i switch off auto flushing?
Or may be i misunderstand samething?

Thanks. Denis.

[gavin.king]

There are two ways to achieve this. One is to use the Hibernate-specific setting FlushModel.NEVER (or FlushMode.MANUAL).

The other way is to make sure that all requests except for the last request run outside of a transaction context.

ie. use Tx.NOT_SUPPORTED

[ido_tamir]

Would it make any sense if pageflow would somehow support this?
Maybe one could add an element where the transaction should begin / commit or rollback and by default be suspended or something along these lines?

Is this a legitimate feature request?

thanks
ido

[gavin.king]

I don't see how this has anything to do with pageflow.

[ido_tamir]

Maybe I am confusing some issues, but I often have this scenario:
a pageflow with branches, where users can create things that should be available for selection within the pageflow, but it should still be possible to cancel the whole thing or submit at the end.
The pageflow exercises the methods of many beans and a central way to manage the transaction behavior would be nice, so I would not have to annotate all the beans/methods - or if their behavior should be different in a different context (i.e. no or different pageflow).

thank you very much
ido

<?xml version="1.0" encoding="UTF-8"?>

<pageflow-definition
 name="bookFlow">
 <start-state name="start" transaction="FlushMode.NEVER">
 <transition name="start" to="chooseBook" transaction="begin"></transition>
 </start-state>
 <page name="chooseBook">
 <transition name="createBook" to="createBook"></transition>
 <transition name="submit" to="submit"></transition>
 <transition name="cancel" to="cancel"></transition>
 </page>
 <page name="createBook">
 <transition name="submit" to="submitBook"></transition>
 <transition name="cancel" to="chooseBook"></transition>
 </page>
 <page name="submitBook">
 <transition name="" to="chooseBook"></transition>
 <transition name="cancel" to="chooseBook"></transition>
 <transition name="submitted" to="chooseBook"></transition>
 </page>
 <page name="submit">
 <transition name="cancel" to="cancel"></transition>
 <transition name="submit" to="submitted"></transition>
 </page>
 <page name="cancel" transaction="rollback"><end-conversation/></page>
 <page name="submitted" transaction="commit"><end-conversation/></page>
</pageflow-definition>

[denis-karpov]

Thanks for you answer.

Yes Ido. I need exactly what you have described. I think it is quite common scenario.

And how to be now?

With EntityManager.setFlushMode() we can set only

javax.persistence.FlushModeType.COMMIT

or

javax.persistence.FlushModeType.AUTO

I tried this:

 private EntityManager em;
 @PersistenceContext(type=EXTENDED)
 public void setEntityManager(EntityManager val){
 val.setFlushMode(FlushModeType.COMMIT);
 em = val;
 }

but it does not work.
I get exception:

Caused by: java.lang.NullPointerException
 at org.jboss.ejb3.entity.ExtendedEntityManager.getPersistenceContext(ExtendedEntityManager.java:59)
 at org.jboss.ejb3.entity.ExtendedEntityManager.setFlushMode(ExtendedEntityManager.java:179)
 at com.colvir.reference.action.ValutaProcAction.setEntityManager(ValutaProcAction.java:41)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:585)
 at org.jboss.ejb3.injection.JndiMethodInjector.inject(JndiMethodInjector.java:97)
 ... 59 more

Thanks. Denis.

[lcoetzee]

I had something similar where I wanted to reject (throw away changes that I have made to entities without it being flushed/commited to the db).

In the end I had to do 3 things.

1. in persistence.xml I prevented hibernate from flushing:

 <property name="hibernate.transaction.flush_before_completion" value="false"/>

2.1. I annotated my the SFSB to prevent transactional behavior on method boundaries:

@Stateful
@Name("contentManagementBean")
@Conversational(ifNotBegunOutcome = "ViewContentHomePage")
@TransactionAttribute(TransactionAttributeType.NOT_SUPPORTED)
public class ContentManagementBean implements Serializable, ContentManagement {

2.2 The method where I had to make the choice (to accept and persist or reject and throw away everything) I annotated so that it requires a new transaction (note that no flushing would occur in any other method that is not annotated with this in this bean)

 @TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)
 public String save() throws Exception {

3. When deciding that I want to reject and prevent flushing I also had to evict that specific object from the hibenate entity manager (this was the key for me ) and reload from the db (otherwise it might be flushed at a later stage)

 HibernateEntityManager hem = (HibernateEntityManager)em;
 hem.getSession().evict(metaContentInfo);
 metaContentInfo = null;
 MetaContentInfo mciOrig = em.find(
 MetaContentInfo.class, mcid);

Or something along this line.

Regards

Louis

[gavin.king]

You should definitely NOT have to do (1). The other steps should be enough.

[lcoetzee]

I will give it a try without 1.

Thanks

L

[lisaanm]

Hi.,
I was fed up with this problem of AUTO flush UPDATE and now its solved it. Thanks Icoetzee for posting the solution.