Thanks you for that tip!
Do I understand you that I should only call makePersistent() if the entity
does Not exist already?
And that if I want an update to fail when the entity does not exist I should
do nothing beyond Transaction.commit()?
What I mean is:
Transaction tx = pm.currentTransaction();
try{
tx.begin();
persistme = pm.getObjectById( Thingy.class, sameKey );
if( persistme != null ) persistme.changeSomeValue(); //
persistme could have been deleted by another thread even though it is not
null
// Note: I do NOT call makePersistent();
tx.commit(); //Question: Is it true that persistme is updated
only if it exists otherwise nothing happens? (or maybe an exception)?
}
finally{
if( tx.isActive() ){
tx.rollback();
}
}
pm.close(); // Question: I know that this can recreate a previously
deleted entity. Will it do so now after I have called tx.commit(); above?
Or do I misunderstand: Is there a call like makePersistent() that will only
update the entity if it esits but fail if it does not?
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