The thread
http://groups.google.com/group/google-appengine-java/browse_thread/thread/2acea43161d8ac5/96c77de6c686526d?lnk=gst
is dealing with the same kind of problem. Basically it's not possible
to filter on the name property. So I guess I have two ways of doing
it.
1/ Creating the key by hand bu I have to know the parent key.
Key key = new KeyFactory.Builder("A", "A").addChild("B",
"B").getKey();
B bp = pm.getObjectById(B.class, key);
2/ Using an extent and filter the name property if I don't know the
parent key
B bp = null;
Extent<B> e = pm.getExtent(B.class);
Iterator<B> it = e.iterator();
while (it.hasNext()) {
B rsb = it.next();
if ("B".equals(rsb.getName())) {
bp = rsb;
break;
}
}
e.closeAll();
On Jan 27, 11:47 pm, Rusty Wright <[email protected]> wrote:
> Yes, as you can surmise, I'm guessing.
>
> What's this annotation on the name property for?
>
> @Extension(vendorName="datanucleus", key="gae.pk-name", value="true")
>
>
>
>
>
> Sydneywrote:
> > Since I declared the parameter with query.declareParameters("String
> > nameParam");, the colon is not valid. As expected I got an exception
> > org.datanucleus.store.query.QueryCompilerSyntaxException: Explicit
> > parameters defined for query, yet implicit parameter syntax
> > (":nameParam") found
>
> > On Jan 27, 4:39 pm, Rusty Wright <[email protected]> wrote:
> >> Do you need a colon in front of nameParam?
>
> >> query.setFilter("name == :nameParam");
>
> >> Sydneywrote:
> >>> The query returns no result.
> >>> ApiProxy.setEnvironmentForCurrentThread(new TestEnvironment
> >>> ());
> >>> ApiProxy.setDelegate(new ApiProxyLocalImpl(new File("."))
> >>> {
> >>> });
> >>> A a = new A("A");
> >>> B b = new B("B");
> >>> a.getBs().add(b);
> >>> PersistenceManagerFactory pmf =
> >>> JDOHelper.getPersistenceManagerFactory("transactions-optional");
> >>> PersistenceManager pm = pmf.getPersistenceManager();
> >>> Transaction tx = pm.currentTransaction();
> >>> try {
> >>> tx.begin();
> >>> pm.makePersistent(a);
> >>> tx.commit();
> >>> } finally {
> >>> if (tx.isActive()) {
> >>> tx.rollback();
> >>> }
> >>> }
> >>> System.out.println(a.getKey());
> >>> A ap = pm.getObjectById(A.class, "A");
> >>> System.out.println(ap.getKey());
> >>> Query query = pm.newQuery(B.class);
> >>> query.setFilter("name == nameParam");
> >>> query.declareParameters("String nameParam");
> >>> List<B> rs = (List<B>) query.execute("B");
> >>> System.out.println(rs.size());
> >>> On Jan 23, 12:20 am, John Patterson <[email protected]> wrote:
> >>>> Execute a query on the name property of B rather than loading it by
> >>>> key. If the name is unique the result should only contain one B.
> >>>> On 23 Jan 2010, at 11:41,Sydneywrote:
> >>>>> I have a one to many relationship. There is a problem in the way I
> >>>>> query for a B object. I was wondering what is the best way (most
> >>>>> efficient) to do that.
> >>>>> A a = new A("A");
> >>>>> B b = new B("B");
> >>>>> a.getBs().add(b);
> >>>>> pm.makePersistent(a); // it's done inside a transaction
> >>>>> A ap = pm.getObjectById(A.class, "A"); // FINE
> >>>>> B bp = pm.getObjectById(B.class, "B"); // NOT FOUND Exception
> >>>>> I guess B is not found because the real key is not B but B + A key.
> >>>>> How do you get the B object when you don't know nothing about A?
> >>>>> public class A {
> >>>>> �...@primarykey
> >>>>> �...@persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
> >>>>> �...@extension(vendorName = "datanucleus", key = "gae.encoded-pk",
> >>>>> value = "true")
> >>>>> private String key;
> >>>>> �...@persistent
> >>>>> �...@extension(vendorName = "datanucleus", key = "gae.pk-name", value
> >>>>> = "true")
> >>>>> private String name;
> >>>>> �...@persistent(mappedBy = "a")
> >>>>> private List<B> bs;
> >>>>> public A(String name) {
> >>>>> this.name = name;
> >>>>> bs = new ArrayList<B>();
> >>>>> }
> >>>>> ... Getter/Setter
> >>>>> }
> >>>>> @PersistenceCapable(identityType =
> >>>>> javax.jdo.annotations.IdentityType.APPLICATION)
> >>>>> public class B {
> >>>>> �...@primarykey
> >>>>> �...@persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
> >>>>> �...@extension(vendorName = "datanucleus", key = "gae.encoded-pk",
> >>>>> value = "true")
> >>>>> private String key;
> >>>>> �...@persistent
> >>>>> �...@extension(vendorName = "datanucleus", key = "gae.pk-name", value
> >>>>> = "true")
> >>>>> private String name;
> >>>>> �...@persistent
> >>>>> private A a;
> >>>>> public B(String name) {
> >>>>> this.name = name;
> >>>>> }
> >>>>> ... Getter/Setter
> >>>>> }
> >>>>> --
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>
> --
> 0x2B | ~0x2b -- Hamlet
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