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From Andy Jefferson <a...@jpox.org>
Subject Re: 2.1 Spec: detached-dirty parameters to makePersistent() when DetachAllOnCommit=true
Date Tue, 07 Aug 2007 19:11:28 GMT
> With this restriction in place, however, would I be able to do the 
> following? 

> // fetch a detched object
> Query q = pm.newQuery(Foo.class);
> q.setUnique(true);
> Foo foo = (Foo) q.execute();

"detachAllOnCommit" will transition instances to detached *at commit*. You 
have no commit here (using nontransactionalRead ?). If you have tx.begin(), 
tx.commit() around it then its definitely fine. Nothing in the spec 
definition of "detachAllOnCommit" implies (to me) that queries run with 
non-tx read will do the detach.

> // make it dirty:
> foo.setBar("bar");

"foo" : detached-clean -> detached-dirty

> // attach
> pm.currentTransaction().begin();
> pm.makePersistent(foo);

"foo" : detached-dirty -> persistent-clean

> pm.currentTransaction().commit();

"foo" : persistent-clean -> detached-clean

> // dirty it once more
> foo.addBaz("baz");

"foo" : detached-clean -> detached-dirty

> // and attach it a second time

"foo" : detached-dirty -> persistence-clean

> - wouldn't this cause the  JDOUserException you mention above? 

No. If referring to the same PM, the object would have been removed from L1 
cache at detach. The exception I was referring to was if you did a separate 
PM.detachCopy() or detached it from a different PM and *then* tried to attach 
to the same PM as one that already had it.

Andy  (Java Persistent Objects - http://www.jpox.org)

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