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Subject: Re: NullPointerException when ObjectContext.commitChanges() called
From: Andrus Adamchik <andrus@objectstyle.org>
In-Reply-To: 
 <CAFtSvbE-DOU1eTxudSJprGCNzm9kOPGfJUCiePsQg8=o7O4AkQ@mail.gmail.com>
Date: Fri, 26 Aug 2011 18:36:38 +0300
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Message-Id: <00660D31-3A10-4AB0-B257-24B2B86D5481@objectstyle.org>
References: 
 <CAFtSvbE-DOU1eTxudSJprGCNzm9kOPGfJUCiePsQg8=o7O4AkQ@mail.gmail.com>
To: user@cayenne.apache.org

I think the reason is that you haven't mapped and DataNodes (at least =
cayenne.xml doesn't have any). DataNode is an abstraction of a DB =
connection pool. E.g. see

=
http://cayenne.apache.org/doc30/tutorial-starting-project.data/base-datano=
de.png

which is a part of the Cayenne tutorial at =
http://cayenne.apache.org/doc30/tutorial-starting-project.html

Andrus

On Aug 26, 2011, at 6:32 PM, Joel Becker wrote:

> Hello. In my app I create an ObjectContext, create some domain =
objects, and call commitChanges(), which causes a NullPointerException =
with the following stack trace:
>=20
> Exception in thread "main" org.apache.cayenne.CayenneRuntimeException: =
[v.3.0.1 Sep 06 2010 15:09:38] Commit Exception
>         at =
org.apache.cayenne.access.DataContext.flushToParent(DataContext.java:1134)=

>         at =
org.apache.cayenne.access.DataContext.commitChanges(DataContext.java:1045)=

>         at net.joelbecker.exercise.App.main(App.java:50)
> Caused by: java.lang.NullPointerException
>         at =
org.apache.cayenne.access.DataDomainInsertBucket.createPermIds(DataDomainI=
nsertBucket.java:101)
>         at =
org.apache.cayenne.access.DataDomainInsertBucket.appendQueriesInternal(Dat=
aDomainInsertBucket.java:76)
>         at =
org.apache.cayenne.access.DataDomainSyncBucket.appendQueries(DataDomainSyn=
cBucket.java:79)
>         at =
org.apache.cayenne.access.DataDomainFlushAction.preprocess(DataDomainFlush=
Action.java:182)
>         at =
org.apache.cayenne.access.DataDomainFlushAction.flush(DataDomainFlushActio=
n.java:134)
>         at =
org.apache.cayenne.access.DataDomain.onSyncFlush(DataDomain.java:824)
>         at =
org.apache.cayenne.access.DataDomain$2.transform(DataDomain.java:791)
>         at =
org.apache.cayenne.access.DataDomain.runInTransaction(DataDomain.java:850)=

>         at =
org.apache.cayenne.access.DataDomain.onSync(DataDomain.java:788)
>         at =
org.apache.cayenne.access.DataContext.flushToParent(DataContext.java:1106)=

>         ... 2 more
>=20
> I created from scratch a data model in Cayenne Modeler, and generated =
the java files from there into a maven project which also includes the =
cayenne.xml and map files in src/main/resources, and App.java in =
src/main/java/<package>. I attached all of my files. I'm using modeller =
3.0.2 and library version 3.0.1.
>=20
> I debugged into the Cayenne code for a while and found that the reason =
the NPE occurs at DataDomainInsertBucket:101 because node is null =
because parent.getDomain().lookupDataNode("Exercise") returns null =
because DataDomain.nodesByDataMapName is empty. I traced the map file =
loading code for a while but haven't figured out where =
nodesByDataMapName is populated and why it is not being populated (my =
breakpoint at the first line of DataDomain.addNode() never hits). Has =
anyone seen this before, or has an idea why it occurs?
>=20
> Thanks.
> -Joel
> <cayenne.xml><Exercise.map.xml>