Re: Problem by Updating an Object

From: Andrus Adamchik (andru..bjectstyle.org)
Date: Mon Feb 16 2004 - 11:22:17 EST

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    Hi Kai,

    I am glad you solved the problem. Now that you've fully described your
    setup, I do understand why it happens.

    > Maybe it is helpful to put a hint in the Installation section of the
    > user
    > guide, which will be intent to this problem.

    We have this advise in the user guide already... Kind of. See a
    "jre/lib/ext" warning and the paragraph below it on this page:
    http://objectstyle.org/cayenne/userguide/install/postinstall.html . I
    guess we can add an Eclipse-specific piece too.

    Andrus

    On Feb 16, 2004, at 5:43 AM, Kai Michael Bodach wrote:

    > Hi Andrus,
    >
    > finally I (and a high qualified co-worker) have solved the problem
    > with my
    > strange environment and cayenne. First I would like to point to an
    > other
    > list thread, which seems describe the same problem and which point us
    > to the
    > real cause of our problem -->
    > http://objectstyle.org/cayenne/lists/cayenne-user/2004/01/0082.html
    > Ok, the reason for the problem is the special way in which we launch
    > the
    > server and load the corresponding classes. In my environment, I load
    > all
    > related projects, like Cayenne or Tapestry as support projects and
    > load the
    > extended jar's via the launch process of Http Server(Jetty) directly
    > out of
    > Eclipse.
    > The problem by this way is, that the classes of the related projects
    > (like
    > cayenne), will be load via the BootstrapClassLoader, but the custom
    > classes
    > of my project, which are located in the WEB-INF/classes folder, will
    > be load
    > with ContextClassLoader of my webapp. Here is a little documentation
    > from
    > Tomcat, which described the classloading way of Tomcat -->
    > http://jakarta.apache.org/tomcat/tomcat-5.0-doc/class-loader-howto.html
    > The different classloaders are the reason, why cayenne won't be able
    > to find
    > the ObjEntity, because Cayenne use a different loaded class as key in
    > some
    > Map's and if I use my class as parameter in a query, then this is not
    > the
    > same which use cayenne and so the right Exception will be thrown -->
    > org.objectstyle.cayenne.CayenneRuntimeException
    > [v.1.0.6 January 26 2004] Class 'MyClass' does not map to an ObjEntity
    > and
    > is therefore not persistent. Can't commit changes
    >
    > Ok I hope everybody can understand my damn bad english. And finally I
    > have
    > to thank you Andrus, for your fast support.
    > Maybe it is helpful to put a hint in the Installation section of the
    > user
    > guide, which will be intent to this problem.
    >
    > Thanks a lot.
    >
    > -kai



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