Finally fixed after a tip from DataNucleus over on stackoverflow...
pm.getFetchPlan().setGroup("decks");
pm.getFetchPlan().setGroup("cards");
should actually be
pm.getFetchPlan().addGroup("decks");
pm.getFetchPlan().addGroup("cards");
The setgroup methods overwrite whatever groups are already there, and
the addgroup methods just add them. Lesson learned the hard way.
On Mar 9, 12:07 am, tempy <[email protected]> wrote:
> All sorts of permutations have still failed to do this for me. From
> searching this group and stackoverflow, I'm starting to wonder if many
> people actually use JDO attach/detach in any significant way.
> Anyone??
>
> On Mar 8, 12:29 am, tempy <[email protected]> wrote:
>
>
>
> > I am trying to load the full object graph for User, which contains a
> > collection of decks, which then contains a collection of cards, as
> > such:
>
> > User:
> > @PersistenceCapable(detachable = "true")
> > @Inheritance(strategy = InheritanceStrategy.SUBCLASS_TABLE)
> > @FetchGroup(name = "decks", members = { @Persistent(name =
> > "_Decks") })
> > public abstract class User {
> > @PrimaryKey
> > @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
> > protected Key _ID;
> > @Persistent
> > protected String _UniqueIdentifier;
> > @Persistent(mappedBy = "_Owner")
> > @Element(dependent = "true")
> > protected Set<Deck> _Decks;
> > protected User()
> > {
> > }
>
> > }
>
> > Each Deck has a collection of Cards, as such:
> > @PersistenceCapable(detachable = "true")
> > @FetchGroup(name = "cards", members = { @Persistent(name =
> > "_Cards") })
> > public class Deck {
> > @PrimaryKey
> > @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
> > private Key _ID;
> > @Persistent
> > String _Name;
> > @Persistent(mappedBy = "_Parent")
> > @Element(dependent = "true")
> > private Set<Card> _Cards = new HashSet<Card>();
> > @Persistent
> > private Set<String> _Tags = new HashSet<String>();
> > @Persistent
> > private User _Owner;
>
> > }
>
> > And finally, each card:
> > @PersistenceCapable
> > public class Card {
> > @PrimaryKey
> > @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
> > private Key _ID;
> > �...@persistent
> > private Text _Question;
> > @Persistent
> > private Text _Answer;
> > @Persistent
> > private Deck _Parent;
>
> > }
>
> > I am trying to retrieve and then detach the entire object graph. I
> > can see in the debugger that it loads fine, but then when I get to
> > detaching, I can't make anything beyond the User object load. (No
> > Decks, no Cards). At first I tried without a transaction to simply
> > "touch" all the fields on the attached object before detaching, but
> > that didn't help. Then I tried adding everything to the default fetch
> > group, but that just generated warnings about GAE not supporting
> > joins. I tried setting the fetch plan's max fetch depth to -1, but
> > that didn't do it. Finally, I tried using FetchGroups as you can see
> > above, and then retrieving with the following code:
>
> > PersistenceManager pm = _pmf.getPersistenceManager();
> > pm.setDetachAllOnCommit(true);
>
> > pm.getFetchPlan().setGroup("decks");
> > pm.getFetchPlan().setGroup("cards");
>
> > Transaction tx = pm.currentTransaction();
>
> > Query query = null;
> > try {
> > tx.begin();
>
> > query = pm.newQuery(GoogleAccountsUser.class);
> > //Subclass of User
> > query.setFilter("_UniqueIdentifier == TheUser");
> > query.declareParameters("String TheUser");
>
> > List<User> results = (List<User>)query.execute(ID);
> > //ID = Supplied
> > parameter
>
> > //TODO: Test for more than one result and throw
> > if(results.size() == 0)
> > {
> > tx.commit();
> > return null;
> > }
> > else
> > {
> > User usr = (User)results.get(0);
>
> > //usr = pm.detachCopy(usr);
> > tx.commit();
> > return usr;
> > }
>
> > } finally {
> > query.closeAll();
> > if (tx.isActive())
> > {
> > tx.rollback();
> > }
> > pm.close();
> > }
>
> > This also doesn't work, and I'm running out of ideas. I'm new to GAE/
> > JDO, so go easy please. =)
>
> > Thanks,
> > Mike
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