I'm not entirely sure it's a problem with "your spring transaction usage".
I have the exact same problem although I'm also using springs
transactions, I'm using the spring annotated transactions.
I find that if I just call entityManager.find() on an object that once the
transaction completes it calls @PreUpdate even if I haven't modified any
fields.
I would have assumed that a transaction.commit() would not cause
@PreUpdate to be called if no changes were made to the object. I tried
looking in the ejb-3_0 spec but it didn't seems to cleary indicate if it
should or should not be called.
I guess I'll try writing a simple test case which shows this.
> I wrote the smallest possible test case to demonstrate the problem (the
> undesired updates after the commit on a transaction that only had reads).
>
> I discovered that the way I was managing Spring Framework's transaction
> handling was causing my problem.
>
> I thought I had to supply the Spring Framework transaction manager with the
> EntityManager that I was using for a thread outside Spring. However, I
> don't need to. It's enough to give Spring the EntityManagerFactory.
>
> The call to the Spring internals with the EntityManager causes the problem,
> although I'm not likely to have time to check out why. This is how I was
> doing it:
>
> TransactionSynchronizationManager.bindResource(
> entityManagerFactory, new EntityManagerHolder(entityManager));
>
> In this way I was assuming that Spring would use this entityManager,
> however for reasons unknown Spring's JpaTransactionManager was ignoring
> this entityManager and calling the EntityManagerFactory to get another -
> the EMF is injected into JpaTransactionManager in the IoC config (from my
> ContextManager):
>
> <bean id="transactionManager"
> class="org.springframework.orm.jpa.JpaTransactionManager">
> <property name="entityManagerFactory">
> <bean class="org.permacode.patternrepo.ContextManager"
> factory-method="getEntityManagerFactory" />
> </property>
> </bean>
>
>
> So OpenJPA's EntityManagerFactory provides a single EntityManager to a
> single thread - presumably storing it in a ThreadLocal - rather than
> creating a new one with entityManagerFactory.createEntityManager().
>
> I presume this is an OpenJPA feature, because I didn't find it in the
> persistence specification.
>
> What do you OpenJPA developers think?
>
>
> thanks
> Adam
>
>
>
> Adam Hardy on 19/12/07 12:53, wrote:
> >Will an Eclipse project be fine for the OpenJPA developers? How about
> >the lib jars? Will m2eclipse and maven be acceptable (certainly would be
> >easiest)?
> >
> >Marc - are you using Spring Framework transaction management?
> >
> >regards
> >Adam
> >
> >Marc Siegel on 18/12/07 14:44, wrote:
> >>It would be worth it to some of us users. Anything that could be done
> >>to get this fixed would help many people.
> >>
> >>-Marc
> >>
> >>On Dec 17, 2007 6:34 PM, Adam Hardy <[EMAIL PROTECTED]> wrote:
> >>>>I also had a situation where OpenJPA fired updates on unchanged
> >>>>entities after
> >>>committing the transaction, for all fields all the time.
> >>>
> >>>For instance, one pojo only had 2 string fields and a Long primary
> >>>key. OpenJPA
> >>>updated both string fields after the commit.
> >>>
> >>>I'm using the extended persistence context without any versioning,
> >>>and the only
> >>>configuration I set is the JDBC connection properties.
> >>>
> >>>Unfortunately I fixed it without figuring out where exactly the
> >>>problem was.
> >>>Sorry. I think what I had done is to begin a transaction, commit it,
> >>>and then
> >>>start another and whatever I pulled into the second transaction,
> >>>OpenJPA did an
> >>>update on.
> >>>
> >>>If you think this is worth putting a test case together for, let me
> >>>know. I
> >>>wasn't quite sure whether running a second transaction after the
> >>>first on the
> >>>same entity manager was legitimate according to the JPA spec.
> >>>
> >>>
> >>>Shelley <[EMAIL PROTECTED]> writes:
> >>>>I am seeing a similar issue with OpenJPA unnecessarily calling an
> >>>>UPDATE on
> >>>>every commit.
> >>>>
> >>>>It appears that on every commit(), all of my entity's Date fields
> >>>>(TemporalType.TIMESTAMP) are being updated even though they have not
> >>>>changed.
> >>>>
> >>>>UPDATE MY_ENTITY SET timeField = ?, version = ? WHERE id = ? AND
> >>>>version = ?
> >>>>[params=(Timestamp) 2007-12-05 15:08:18.927, (int) 2, (int) 50,
> >>>>(int) 1]
> >>>>
> >>>>My current workaround is to clear the persistence context after each
> >>>>commit,
> >>>>but this obviously is not desirable and shouldn't be necessary. Any
> >>>>ideas
> >>>>as to why this might be occurring, or how to prevent it? I am using
> >>>>the
> >>>>majority of default OpenJPA properties (version LockManager, optimistic
> >>>>locking, etc), although I have attempted to modify some of these
> >>>>properties
> >>>>to prevent this problem, so far with no success.
> >
> >
>
--
Ted Leung
[EMAIL PROTECTED]
It is easier to speak wisely than to act wisely.
