Check out this blog post:
http://gae-java-persistence.blogspot.com/2009/10/creating-bidrectional-owned-one-to-many.html
I'm pretty sure you want to be persisting the thread and not the
comment. If you make it un-owned, you want the thread to have a key
and a user, then each comment has a key and a parent key which is the
key of the thread it belongs to. if you do a query where parent key
== thread key you should get all the comments that belong to the
thread.
On Feb 22, 7:06 pm, "Fernando O." <fot...@gmail.com> wrote:
> tried that and it's telling me
> org.datanucleus.exceptions.NucleusObjectNotFoundException: Could not
> retrieve entity of kind Thread with key Thread(51)
>
> I also tried doing a query with the Thread key and UserKey (wich is the key
> for a thread) and then I get an exception about modifying 2 entities in 1
> transaction :S
>
> On Tue, Feb 22, 2011 at 8:56 PM, Fernando O. <fot...@gmail.com> wrote:
> > Thanks! I'll try that. BTW no, addComment does not store the comment.
>
> > On Tue, Feb 22, 2011 at 8:49 PM, WillSpecht <willspe...@gmail.com> wrote:
>
> >> Don't you need to persist the thread as well as the comment? It's
> >> hard to analyze your code with such a small sample. Does addComment
> >> persist the thread? My
> >> guess is that something is making the transaction fail, probably
> >> cause you are trying to operate on two different entity groups. I
> >> would simply store the comment as it's own entity and when you want
> >> all the comments simply do a query for comments with parentKey ==
> >> ThreadKey.
>
> >> On Feb 21, 9:30 pm, "Fernando O." <fot...@gmail.com> wrote:
> >> > Hi all.
> >> > First of all I have to admit: I havent read all the docs.
>
> >> > I had a small app running, it basically has this:
> >> > A User:
> >> > @PersistenceCapable(detachable = "true")
> >> > @FetchGroup(name = "_post", members = { @Persistent(name = "posts") })
> >> > public class User implements Serializable{
> >> > @PrimaryKey
> >> > @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
> >> > private Key key;
> >> >> @Persistent(mappedBy = "user", defaultFetchGroup = "true")
> >> > @Element(dependent = "true")
> >> > private List<Post> posts;
> >> > ....}
>
> >> > A thread :
>
> >> > @PersistenceCapable(detachable = "true")
> >> > @FetchGroup(name = "_user", members = { @Persistent(name = "user")})
> >> > public class Thread implements Serializable {
> >> > @PrimaryKey
> >> > @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
> >> > private Long key;
>
> >> > @Persistent(defaultFetchGroup = "true")
> >> > @Element(dependent = "true")
> >> > private User user;
> >> > ...
>
> >> > }
>
> >> > So now I want to add comments, each comment will have: the user that
> >> made
> >> > the comment, and the thread that it belongs to, and some other fields:
> >> > @PersistenceCapable(detachable = "true")
> >> > public class ThreadComment implements Serializable{
> >> > @PrimaryKey
> >> > @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
> >> > private Key key;
>
> >> > @Persistent(defaultFetchGroup = "true")
> >> > @Element(dependent = "true")
> >> > private User user;
>
> >> > @Persistent(defaultFetchGroup = "true")
> >> > @Element(dependent = "true")
> >> > private Thread thread;
> >> > ...
>
> >> > }
>
> >> > I changed the Thread to include a list of comments:
> >> > @PersistenceCapable(detachable = "true")
> >> > @FetchGroup(name = "_user", members = { @Persistent(name =
> >> > "comments"),@Persistent(name
> >> > = "user")})
> >> > public class Thread implements Serializable {
> >> > ....
> >> > @Persistent(defaultFetchGroup = "true")
> >> > @Element(dependent = "true")
> >> > private List<ThreadComment> comments;
>
> >> > }
>
> >> > My problem is that meanwhile this works in memory when I try to persist
> >> the
> >> > ThreadComment
> >> > PersistenceManager pm = getPMF();
> >> > Transaction tx = pm.currentTransaction();
> >> > tx.begin();
> >> > thread.addComment(comment);
> >> > pm.makePersistent(comment);
> >> > tx.commit();
> >> > pm.close();
>
> >> > the code gets excecuted but I don't see the comment in the database (in
> >> fact
> >> > the logs show no db activity either)
> >> > So I don't see an exception, the code gets excecuted but I don't see the
> >> > comment in the DB.
>
> >> > I already have the db with soem threads without comments, this is a "new
> >> > feature"
>
> >> > Any idea of what I'm doing wrong? (please don't say everything :D )
>
> >> > Thanks!
>
> >> > Fernando
>
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