| Re: [eclipselink-users] RE: Strange issue in merging changes. |
Hello Chris,
I didn’t get the Tim’s mail you referred below. Not sure if it didn’t reach me somehow.
However what difference I find using @Transactional(readOnly=false) (this doesn’t work i.e. parent entity changes are lost) and @Transactional (readOnly=true) (This works all fine) is that the former way the early transaction is started on the UnitOfWork. The following code is getting executed in the first case. This is EL specific code which is called in the EclipseLink integration code in spring orm.
UnitOfWork uow = (UnitOfWork) getSession(entityManager);
uow.beginEarlyTransaction();
Due to beginEarlyTransaction call on the UoW I find that if a child entity is accessed meanwhile (or loaded due to EAGER fetchType set on the OneToMany relation) which has relation with parent as
ManyToOne with cascade type as REFRESH the changes are lost when the execution reaches in ObjectBuilder for merging the changes in the child entity.
I will try out your suggestion for debugging and answer your queries below and will also provide log set at Finer level in some time.
Thanks so much for your help,
Shashi
From: eclipselink-users-bounces@xxxxxxxxxxx [mailto:eclipselink-users-bounces@xxxxxxxxxxx] On Behalf Of Christopher Delahunt
Sent: Wednesday, July 28, 2010 7:31 PM
To: EclipseLink User Discussions
Subject: Re: [eclipselink-users] RE: Strange issue in merging changes.
Hello Shashi,
I'm not all that familiar with Spring, so I don't know if this could be something to do with its interactions, but you might try the suggestion Tim made about using propagation on your transaction.
Looking at EclipseLink though, it seems you are able to debug the EclipseLink-Spring integration code and the application. Are you able to see why the Child is referencing a different instance
of the Parent than is referencing it? This shouldn't happen, but depending on how you are managing your entities and setting relations though, its not disallowed. Also, are you saying that the entity
returned from em.merge doesn't have the changes that are in the entity passed in, or do the changes revert later on? Does the collection of children include new ones?
Also, what other settings are you using (customizers, event listeners, properties that change cache behavior etc)? If something you do causes a refresh on Child, this will force a refresh on the parent as well (with the cascade refresh option), causing you to loose the changes.
Can you set the eclipselink.logging.level property to Finest and show the log generated up to where you check the merged parent for the changes.
Best Regards,
Chris
On 28/07/2010 9:10 AM, Shashikant Kale wrote:Can an EL dev team member please share thought on why this would be happening. This has come as a critical issue for us and we are struggling to get an alternative to make it work.
Regards,
Shashi
From: eclipselink-users-bounces@xxxxxxxxxxx [mailto:eclipselink-users-bounces@xxxxxxxxxxx] On Behalf Of Shashikant Kale
Sent: Tuesday, July 27, 2010 4:35 PM
To: EclipseLink User Discussions
Subject: [eclipselink-users] RE: Strange issue in merging changes.
Also,
Figured out that, in spring, if a transaction is writable, i.e. readOnly=false, an early transaction is started on the current UoW. The code is
if (!definition.isReadOnly() && !this.lazyDatabaseTransaction) {
// This is the magic bit. As with the existing Spring TopLink integration,
// begin an early transaction to force EclipseLink to get a JDBC Connection
// so that Spring can manage transactions with JDBC as well as EclipseLink.
UnitOfWork uow = (UnitOfWork) getSession(entityManager);
uow.beginEarlyTransaction();
}
And it is writable, an early transaction is started and the changes done to the parent are lost during merge. I couldn’t figure out how this changes the behavior, but looks like it does.
Can somebody please throw some light on this?
Thanks,
Shashi
From: eclipselink-users-bounces@xxxxxxxxxxx [mailto:eclipselink-users-bounces@xxxxxxxxxxx] On Behalf Of Shashikant Kale
Sent: Tuesday, July 27, 2010 2:34 PM
To: EclipseLink User Discussions
Subject: [eclipselink-users] Strange issue in merging changes.
Hi,
We have been using Eclipselink 1.2.0 with Spring.
We have configured Spring transaction interceptor (Using @Transactional(readOnly=false)) to manage the transactions in our Service code.
Parent {
@OneToMany(mappedBy="parent", cascade={CascadeType.ALL}, fetch=FetchType.EAGER)
@org.eclipse.persistence.annotations.PrivateOwned
protected List<Child> children = new ArrayList<Child>();
}
Child {
@ManyToOne(cascade={CascadeType.REFRESH}) @JoinColumn(name="SOME_CHILD_ID")
protected Parent parent;
}
Service {
@Transactional (readOnly=false)
public void serviceMethod (Parent parent){
parent.setData(“data”);
……
……
Parent merged = em.merge(parent);
// Here the merged parent has lost the changes i.e. data
}
}
However I am seeing a strange issue in merging the changes for an entity which has a child entity with OneToMany relation. The changes done to the entity are getting lost. When I debugged into EL code, I went inside merge code where changes are calculated for an entity, however in org.eclipse.persistence.internal.descriptors.ObjectBuilder class I find that when the OneToMany mapping is being merged in the method while traversing through the DatabaseMapping, it calls further to merge changes in the Child, the target entity instance i.e. child entity instance doesn’t contain the latest parent entity with the changes. Hence the changes of the parent are getting lost.
public void mergeIntoObject(Object target, boolean isUnInitialized, Object source, MergeManager mergeManager, boolean cascadeOnly, boolean isTargetCloneOfOriginal)
However if I remove CascadeType.REFRESH in the ManyToOne mapping inside Child it works fine. Also if I mark the service method as @Transactional (readOnly=true) it works fine either.
Is there anything wrong in the entity relationship setup?
Kindly let me know.
TIA,
Shashi
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