Marcus Christie created AIRAVATA-2872:
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Summary: registry-refactoring: OpenJPA doesn't persist setting a
field to null
Key: AIRAVATA-2872
URL: https://issues.apache.org/jira/browse/AIRAVATA-2872
Project: Airavata
Issue Type: Bug
Components: Registry API
Reporter: Marcus Christie
Assignee: Marcus Christie
In OpenJPA, the default handling of null values on detached instances is to
treat them as "unloaded" meaning it treats them as if they are simply missing
instead of treating them as having been set to null.
See https://stackoverflow.com/a/2569417/1419499
See also official docs:
http://openjpa.apache.org/builds/2.4.3/apache-openjpa/docs/ref_guide_remote.html#ref_guide_detach,
however it's hard to understand how to make use of this in our context.
See also this discussion
http://openjpa.208410.n2.nabble.com/null-values-not-updating-td3224059.html
I traced the OpenJPA code to these lines in VersionAttachStrategy:
{code:java}
int detach = (isNew) ? DETACH_ALL : broker.getDetachState();
FetchConfiguration fetch = broker.getFetchConfiguration();
try {
FieldMetaData[] fmds = sm.getMetaData().getFields();
for (int i = 0; i < fmds.length; i++) {
switch (detach) {
case DETACH_ALL:
attachField(manager, toAttach, sm, fmds[i], true);
break;
case DETACH_FETCH_GROUPS:
if (fetch.requiresFetch(fmds[i])
!= FetchConfiguration.FETCH_NONE)
attachField(manager, toAttach, sm, fmds[i], true);
break;
case DETACH_LOADED:
attachField(manager, toAttach, sm, fmds[i], false);
break;
}
}
} finally {
{code}
The detach state is {{DETACH_LOADED}} which causes OpenJPA to treat nulls as
unloaded and thus it skips merging those values in.
I think with a configuration change we can get this to work, but it's not
obvious what all the flags mean, so this will take some research.
One other question I have, is how did this work before. It would be worth
checking to see how the old registry code had configured OpenJPA.
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