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From Michael Gentry <>
Subject Re: DataObject as Beans possible?
Date Thu, 31 Dec 2009 22:39:55 GMT
Keep in mind Cayenne objects are designed to work in a DataContext as
it tracks changes, etc.  It is best to create them in the DC even if
you never persist them later (you can throw the DC away if you want).
Cayenne creates temporary IDs for objects and because you didn't
create it in the DC, the ID is probably null and that's why you are
getting the NPE.  (At least that is my first guess.)

I use my Cayenne objects (the non-underscore) ones as beans,
essentially, often.  Works just fine, but I always create them in the
DC, too.  I also put my business logic in the non-underscore classes,
too.  No issues with that.


On Thu, Dec 31, 2009 at 5:26 PM, Marek Šabo <> wrote:
> Hi,
> another thing, I was thinking whether it is possible or not to use generated
> dataObjects (not the underscored ones) as beans. I defined a constructor and
> filled in all attributes but when I tried to fill foreign key attribue (a
> user in reservation object) stack run into null pointer exception in
> setToOneTarget method on line getObjectContext().propertyChanged(this,
> relationshipName, oldTarget, value);
> It is logicall that datacontext is null as I didn't want any persistance
> (and didn't create this object with newObject method) just models, the
> question is why the holdup on foreign key? Other attributes were passed just
> fine. Or how it is generally done -- e.g. there is another subset of beans
> same as dataObjects for business logic purposes or can it be done the way I
> see it? Frankly, that was the first thing that I got on my mind when I saw
> that dataObjects extending _autoClasses.
> Regards
> --
> Marek Šabo
> Chief Server Manager
> Club SU CVUT Buben
> Bubenečská Kolej
> Terronská 28, Prague 16000

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