Transient objects question

From: Dave Lamy (davelam..mail.com)
Date: Sun Jun 21 2009 - 22:07:17 EDT

  • Next message: Michael Gentry: "Re: Transient objects question"

    Quick question/problem on transient objects:

    I've got a persistent class AppVersion, which simply tracks a version of the
    code/database values for migration purposes. I want to have a persistent
    AppVersion in the database, but then create a transient AppVersion
    representing the code version for comparison purposes.

    So I did what came naturally for the transient object (using
    Cayenne-generated _AppVersion/AppVersion classes):

    AppVersion codeVersion = new AppVersion();
    codeVersion.setMajorNumber(1);

    But I get an exception (3.0 M5):

    java.lang.NullPointerException
        at
    org.apache.cayenne.util.ObjectContextGraphAction.handlePropertyChange(ObjectContextGraphAction.java:59)
        at
    org.apache.cayenne.access.DataContext.propertyChanged(DataContext.java:1591)
        at
    org.apache.cayenne.CayenneDataObject.writeProperty(CayenneDataObject.java:226)
        ...

    The ObjectContextGraphAction is pulling the ObjectId, which is null in the
    transient object.

    What am I doing wrong here? How can I create a transient object and write
    property values without getting this NPE?

    Thanks for the help--
    Dave

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