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From "Willis Blackburn (JIRA)" <>
Subject [jira] Created: (OPENJPA-1804) NPE in line 1514
Date Sat, 18 Sep 2010 19:54:33 GMT
NPE in line 1514

                 Key: OPENJPA-1804
             Project: OpenJPA
          Issue Type: Bug
    Affects Versions: 2.0.1
            Reporter: Willis Blackburn

I am encountering a NPE at line 1514.  I'm sorry I don't have time to prepare
a test case right now.  I'm not even 100% sure what is causing the problem, but it seems to
be something like this:

I have classes Organization, Group, User, and AddressBook.

Group has a reference (many-to-one) to Organization.

I'm using field-level access and the Java 6 runtime enhancer.  (NOT the build-time enhancer
or the agent.)

In ManagedClassSubclasser.prepareUnenhancedClasses, the code receives a list of Class objects--the
ones in persistence.xml.  They are not in the same order as they are in persistence.xml, but
I don't know if that's important.  The first one is Group.  During the processing of Group,
the code invokes ClassMapping.setTable to set the table name, which is "group_table."  This
comes from the @Table annotation of Group.  So far, so good.  Then the code does some additional
processing on the relationship mappings of Group, which include the reference to Organization.
 During the processing of that relationship, the code calls MappingInfo.mergeJoinColumn. 
On line 1367, the method calls rel.getTable.  The "rel" variable points to the ClassMapping
for Organization.  Remember that prepareUnenhancedClasses hasn't gotten to Organization yet--it's
still working on Group--and so I assume that this Organization mapping was created on-demand.
 However, rel.getTable returns null.  The Organization class has a @Table attribute, and I
can see that the table name has been loaded in the ClassMappingInfo instance attached to the
ClassMapping for Organization, however the table name has not yet been copied from ClassMappingInfo
to ClassMapping.  Later, the mergeJoinColumn method attempts to dereference the null table
name and generates the NPE.

Bottom line:  When using the Java 6, runtime enhancer, if class A has a reference to class
B, and both classes have @Table annotations (at least), and class A is processed first, then
it produces a NPE.

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