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https://issues.apache.org/jira/browse/OPENJPA-722?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12632708#action_12632708
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Jeremy Bauer commented on OPENJPA-722:
--------------------------------------
I conversed with a couple of the committers and the consensus was that we
should not be storing persistence context-type state in the detached entities.
Instead, the detached entity should only manage information about the state of
its persistent fields.
So, when we re-merge entities we should not depend on the "NEW" state in a
detached object. The entity could have been inserted into the database outside
of the application, in which case we'd fail trying to do an insert (which
should not happen on a merge). I think the ideal solution is to re-query for
the entity and then perform the insert or update based on whether the entity
was or was not found - similar to merging an actual new entity.
One additional item: The test code has a query immediately following the clear:
em.clear();
assertEquals(1, query("select x from Item x "
+ "where x.itemName = 'cup'").
getResultList().size());
This essentially loads the returned item in the L1 cache, changing the behavior
of the internal merge processing (the corresponding merge finds the item in
the L1). While this is a good scenario to test, we should also test the
scenario where the item isn't cached before the merge.
> persist - clear - merge scenario doesn't work
> ---------------------------------------------
>
> Key: OPENJPA-722
> URL: https://issues.apache.org/jira/browse/OPENJPA-722
> Project: OpenJPA
> Issue Type: Sub-task
> Components: kernel
> Affects Versions: 1.0.3, 1.1.0, 1.2.0
> Reporter: Xiaoqin Feng
> Assignee: Jeremy Bauer
> Attachments: openjpa-722-fromQin.patch,
> TestEntityManagerClear-V2.java, TestEntityManagerClear.java
>
>
> EntityManager.clear() now don't flush new object but only detach it.
> But DetachManager still flush dirty object and assume detached objects are in
> clean state.
> When the "new" object is merged back and transaction commit, because the
> object state lost its original state PNEW, it will not be added to insert
> list and not flushed to DB.
> According to the EntityManager.clear() API, changes made to entities that
> have not been flushed to the database will not be persisted. When they
> merges back to persistent context, they all should kept there original state.
> I added the following test to
> org.apache.openjpa.persistence.simple.TestEntityManagerClear.
> public void testClearMerge() {
> // Create EntityManager and Start a transaction (1)
> begin();
> // Insert a new object then clear persistent context
> AllFieldTypes testObject1 = new AllFieldTypes();
> testObject1.setStringField("my test object1");
> persist(testObject1);
> //Object1 is not flushed to DB but only detached by clear().
> em.clear();
> em.merge(testObject1);
> //expect the PCState is same as before detached,
> //so it is PNew instead of PCLEAN and is add to insert list.
> commit();
>
> //Start a new transaction
> begin();
>
> // Attempt retrieve of Object1 from previous PC (should exist)
> assertEquals(1, query("select x from AllFieldTypes x "
> + "where x.stringField = 'my test object1'").
> getResultList().size());
>
> // Rollback the transaction and close everything
> rollback();
> }
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