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https://issues.apache.org/jira/browse/OPENJPA-1873?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13166110#comment-13166110
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Mark Struberg commented on OPENJPA-1873:
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Thanks for the review Kevin!
Indeed, the problem I faced for a long time was that PostLoad was pretty much
broken, because the payload entity you get into this event was always
different, depending on the situation.
I agree with what Rick and Pinaki pointed out above, that the spec is not
really clear if PostLoad should get fired for a merge at all. But OpenJPA
actually _did_ fire it in _some_ cases, and the entity which got handed to the
event was a mixture between the entity in memory, the state on the database and
the lazy-loaded delta. Again: it was not _one_ of those 3, but it was a weird
mixture with some fields nulled out, etc. And it was depending on _loaded,
_dirty and the detached state. So basically the PostLoad event was not usable
for users once the entity got detached.
Because of that, I would be in favour to even make PostLoadOnMerge enabled by
default - but that's a policy decision which is not up to me to decide. Please
note that the behaviour only got changed if there is any PostLoad lifecycle
listener registered on the entity at all!
With the PostLoadOnMerge flag enabled, OpenJPA now behaves the same way as I
saw with latest Hibernate and EclipseLink - I actually don't care much about
those other impls, but I think it's at least not a bad thing ;)
I was not really sure about the String property based configuration, so I
decided to go full route. If you say this is not supported anymore in
openjpa-2.x, then we should think about Deprecating those parts at all?
Regarding the documentation - thanks for the pointer! I thought those get
generated out from the JavaDoc. Will fix those parts in the doc by adding the
property.
> EntityManager#merge sometimes passes wrong entity values to @PostLoad
> EntityListeners
> --------------------------------------------------------------------------------------
>
> Key: OPENJPA-1873
> URL: https://issues.apache.org/jira/browse/OPENJPA-1873
> Project: OpenJPA
> Issue Type: Bug
> Components: kernel
> Affects Versions: 2.0.0, 2.0.1, 2.0.2
> Reporter: Mark Struberg
> Assignee: Mark Struberg
> Fix For: 2.2.0
>
> Attachments: OPENJPA-1873-fix1.patch, OPENJPA-1873-fix2.patch,
> OPENJPA-1873-fix3.patch, OPENJPA-1873-unittest.patch,
> openjpa-1873-hack-1.patch, postloadtest.zip
>
>
> I've tested this with the latest from branches/2.0.x.
> My entity has an @EntityListeners which observes the @PostLoad lifecycle
> event. This listener stores the 'old' values from the database for later use
> (see http://struberg.wordpress.com/2010/07/31/howto-changelog-with-jpa/ for
> the intention behind). All works well if the table has only a few rows. But
> if you add more rows, OpenJPA tries to optimize the access and only loads the
> @Version field + the dirty fields. In this case the merging seems to be
> wrong, because I get the NEW values from the dirty fields instead of the
> original values from the database passed to my @PostLoad method.
> Did cost me a few grey hairs to track down the differences between the
> working and the broken scenarios here ;) But finally I was able to creat a
> unit test showing the problem
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