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get original Object state from Session [message #554752]

Tue, 24 August 2010 10:46

Radu

Messages: 12
Registered: August 2010

Junior Member

Hi,

I need to get the original object state before an update() is called, by using JpaEntityManager from an EJB Interceptor.

I managed to get the original object by extending DescriptorEventAdapter, in the aboutToUpdate(DescriptorEvent event) method by using event.getOriginalObject().

The problem is that I can not inject @Resources in the DescriptorEventAdapter class and I need to perform some logic by using other helpers EJBs.

In the interceptor however, I can inject resources and get the JpaEntityManager, UnitOfWorkChangeSet and Session by using

JpaEntityManager jpaEntityManager = (JpaEntityManager)em.getDelegate();

UnitOfWorkChangeSet changeSet = (UnitOfWorkChangeSet)jpaEntityManager.getUnitOfWork().getCur rentChanges();

The QUESTION is how can I get the original object state (which is obviously stored in memory) from the current Active Session or UnitOfWork?

Any hint will be appreciated.

Thanks!

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Re: get original Object state from Session [message #555405 is a reply to message #554752]

Thu, 26 August 2010 14:09

James Sutherland

Messages: 1939
Registered: July 2009
Location: Ottawa, Canada

Senior Member

To get the object in the Session cache (current committed state, not necessarily original state), use,

session.readObject(object)

or if a UnitOfWork,

unitOfWork.getParent().readObject(object)

To get the changes for an object use,

unitOfWork.getCurrentChanges().getObjectChangeSetForClone(ob ject)

if you use deferred change tracking the UnitOfWork also stores a backup clone, which is the original state. If you use attribute change tracking (default with weaving), then there is no original state stored, only a set of changes.

James : Wiki : Book : Blog : Twitter

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Re: get original Object state from Session [message #555423 is a reply to message #555405]

Thu, 26 August 2010 14:33

Radu

Messages: 12
Registered: August 2010

Junior Member

Thanks for reply James!

There is any way to get the old value from the set of changes?
I see the method getNewValue(), but there is no getOldValue() method.

This is why I need the backup clone, so I can retrieve the original value for the changed attributes.

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Re: get original Object state from Session [message #556004 is a reply to message #554752]

Mon, 30 August 2010 14:14

James Sutherland

Messages: 1939
Registered: July 2009
Location: Ottawa, Canada

Senior Member

The change set does not currently store the old value. Please log a bug for this and vote for it.

Currently you would need to track the old value yourself, or switch to deferred change tracking to be able to access the backup clone.

James : Wiki : Book : Blog : Twitter

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