Hello Payam Thanks for looking into this. Please see inline On Sun, Feb 21, 2010 at 3:25 PM, Payam <pmoghad...@gmail.com> wrote:
> Hello Aswath, > > What you are doing seems really odd to me. From my understanding a > Datastore Key consists of multiple components. > "A complete key includes several pieces of information, including the > application ID, the kind, and an entity ID" - GAE Docs > > If you use encoded key strings, you can get access to these other > pieces of information: > @PrimaryKey > @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) > @Extension(vendorName="datanucleus", key="gae.encoded-pk", > value="true") > private String encodedKey; > > @Persistent > @Extension(vendorName="datanucleus", key="gae.pk-name", value="true") > private String keyName; > > @Persistent > @Extension(vendorName="datanucleus", key="gae.pk-id", value="true") > private Long keyId; > > In this case, you have access to the name ID (keyName) and numeric ID > (keyID) of the encoded key. Therefore, from my understanding, you can > not change the name ID after you have persisted your first object. The > first object determines the name ID for all remaining objects (from my > understanding). This is why when you try to change it for the second > object, you get an exception. > Your understanding is not documented. Please see 'encodedStrings' in http://code.google.com/appengine/docs/java/datastore/creatinggettinganddeletingdata.html#Keys. > > Perhaps, you can better explain why you are using the "gae.pk-name" > extension for the name. The context of your code is not clear! > "When using encoded key strings, you can provide access to an object's string or numeric ID with an additional field:" I am using the gae-pk-name, so that I can identity the entity uniquely. - if it is associated with a parent, I do, KeyFactory.createKey (parentkey, kind, name) and then access the entity. - if it is not associated with the parent, I do KeyFactory.createKey(kind, name) and then access the entity. I use this entity to store default values for the entity in my application. Thanks, -Aswath Thanks! > > > On Feb 16, 11:38 pm, aswath satrasala <aswath.satras...@gmail.com> > wrote: > > any help on this please... > > > > Thanks. > > > > On Fri, Feb 12, 2010 at 3:18 PM, aswath satrasala < > > > > > > > > aswath.satras...@gmail.com> wrote: > > > Hello Ikia > > > As suggested by you in the thread 'Incorrect number of entities > returned', > > > I have attached the complete files in my previous email. > > > Please let me know, what am I doing wrong here. > > > > > Thanks > > > -Aswath > > > > > On Tue, Feb 9, 2010 at 3:06 PM, aswath satrasala < > > > aswath.satras...@gmail.com> wrote: > > > > >> Hello Ikai, > > >> Attached is the zip file that contains three files > > >> A.java > > >> B.java > > >> BTest.java > > > > >> Please load in your environment and test it. > > > > >> Thanks. > > >> -Aswath > > > > >> On Fri, Feb 5, 2010 at 4:36 PM, aswath satrasala < > > >> aswath.satras...@gmail.com> wrote: > > > > >>> B list is missing from class A in my previous posting. Here is the > > >>> complete A class... > > > > >>> @PersistenceCapable(identityType = IdentityType.APPLICATION) > > >>> public class A { > > >>> @PrimaryKey > > >>> @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) > > >>> @Extension(vendorName = "datanucleus", key="gae.encoded-pk", > > >>> value="true") > > >>> private String id; > > > > >>> @Persistent > > >>> @Extension(vendorName = "datanucleus", key="gae.pk-name", > > >>> value="true") > > >>> private String name; > > > > >>> @Persistent > > >>> private List<B> bList ; > > > > >>> } > > > > >>> On Fri, Feb 5, 2010 at 4:32 PM, aswath satrasala < > > >>> aswath.satras...@gmail.com> wrote: > > > > >>>> This is a similar posting I had posted earlier "incorrect number of > > >>>> entities returned". Hopefully, this posting may be more clean and I > will > > >>>> get some replies. > > >>>> I have two classes > > >>>> 1) A > > >>>> 2) B > > >>>> A is in 1 to many relationship with B > > >>>> @PersistenceCapable(identityType = IdentityType.APPLICATION) > > >>>> public class A { > > >>>> @PrimaryKey > > >>>> @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) > > >>>> @Extension(vendorName = "datanucleus", key="gae.encoded-pk", > > >>>> value="true") > > >>>> private String id; > > > > >>>> @Persistent > > >>>> @Extension(vendorName = "datanucleus", key="gae.pk-name", > > >>>> value="true") > > >>>> private String name; > > >>>> } > > > > >>>> @PersistenceCapable(identityType = IdentityType.APPLICATION) > > >>>> public class B { > > >>>> @PrimaryKey > > >>>> @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) > > >>>> @Extension(vendorName = "datanucleus", key = "gae.encoded-pk", > value > > >>>> = "true") > > >>>> private String id; > > > > >>>> @Persistent > > >>>> @Extension(vendorName = "datanucleus", key = "gae.pk-name", > value = > > >>>> "true") > > >>>> private String name; > > >>>> } > > > > >>>> public class BTest extends JDOTestCase { > > > > >>>> public void testB() throws Exception { > > >>>> A a = new A(); > > >>>> a.setName("a"); > > >>>> B b = new B(); > > >>>> b.setName("b"); > > >>>> a.getBList().add(b); > > > > >>>> beginTxn(); > > >>>> pm.makePersistent(a); > > >>>> a = pm.getObjectById(A.class, a.getId()); > > >>>> assertEquals(1, a.getBList().size()); > > >>>> commitTxn(); > > > > >>>> B b1 = new B(); > > >>>> b1.setName("b1"); > > >>>> beginTxn(); > > >>>> pm.makePersistent(b1); > > >>>> b1 = pm.getObjectById(B.class, b1.getId()); > > >>>> b1.getId(); > > >>>> commitTxn(); > > >>>> } > > >>>> } > > > > >>>> The test fails at the last line "b1.getId()" > > >>>> If any of B entity is in relation with A earlier, then another > entity of > > >>>> B cannot be persisted by itself. > > > > >>>> If I move the 2nd transaction to the beginning, the test passes. > > > > >>>> -Aswath > > -- > 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=en. > > -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. 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