That sounds like a good topic for a Snippets That Work blog post. I don't have time to construct the example for you but I'd recommend reading
http://www.datanucleus.org/products/accessplatform_1_1/jdo/fetchgroup.html If after reading this you're still not able to get your code working, please post your model objects and your code and I can take a look. Max On Fri, Nov 13, 2009 at 11:49 AM, IlyaE <ilyaelk...@gmail.com> wrote: > Max, > > Can you please provide an example of how to set the Account in a fetch > group? What about detaching the entire Project object and then saving > it in the session? > > On Nov 13, 1:50 pm, "Max Ross (Google)" > <maxr+appeng...@google.com<maxr%2bappeng...@google.com> > > > wrote: > > Presumably you have a Project in your HttpSession with a null Account. > This > > is most likely related to FetchGroups. You probably want to put your > > Project.account field in the default fetch group. That way it will > always > > be available when you close the persistence manager you used to load the > > Project. > > > > > > > > On Thu, Nov 12, 2009 at 7:29 PM, IlyaE <ilyaelk...@gmail.com> wrote: > > > I'm seeing an odd issue when loading my jsps for the first time (after > > > deployment). > > > > > I have an Account object that has many Projects > > > [Account] > > > @Persistent(mappedBy = "account") > > > private List<Key> projects; > > > > > and on the otherside > > > [Project] > > > @Persistent > > > private Key account; > > > > > Now when i first load my jsp that is forwarded from a servlet, i get a > > > NPE on the "Long id = p.getAccount().getId();" in this code > > > > > Project p = (Project) > request.getSession().getAttribute("project"); > > > Account account = null; > > > if (p != null) { > > > Long id = p.getAccount().getId(); > > > account = pm.getObjectById(Account.class, id); > > > > > I know p is not null (since this code runs) and i know that it is > > > associated with an account. > > > > > The really odd thing is... If i refresh the page, everything works as > > > expected. So this NPE only occurs after i deploy a new version of the > > > app, or certain files expire. > > > Do i need to initialize anything? > > > > > Thanks! > > > > > -- > > > > > You received this message because you are subscribed to the Google > Groups > > > "Google App Engine for Java" group. > > > To post to this group, send email to > > > google-appengine-j...@googlegroups.com. > > > To unsubscribe from this group, send email to > > > google-appengine-java+unsubscr...@googlegroups.com<google-appengine-java%2bunsubscr...@googlegroups.com><google-appengine-java%2B > unsubscr...@googlegroups.com> > > > . > > > For more options, visit this group at > > >http://groups.google.com/group/google-appengine-java?hl=. > > -- > > You received this message because you are subscribed to the Google Groups > "Google App Engine for Java" group. > To post to this group, send email to > google-appengine-j...@googlegroups.com. > To unsubscribe from this group, send email to > google-appengine-java+unsubscr...@googlegroups.com<google-appengine-java%2bunsubscr...@googlegroups.com> > . > For more options, visit this group at > http://groups.google.com/group/google-appengine-java?hl=. > > > -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=.
