Hi.
I'm using 1.3.0, but further investigations shows that this might not
be related to lazy loading after all.
I don't seem to be able to save/retrieve lists of embedded objects at
all...
I wrote some test examples to show my problem. I probably do something
wrong here, but I really can't figure out what...
@PersistenceCapable(identityType = IdentityType.APPLICATION)
public class Test {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
@Extension(vendorName="datanucleus", key="gae.encoded-pk",
value="true")
private String iEncodedKey;
@Persistent(defaultFetchGroup = "true")
private List<InnerTest> innerTests;
@PersistenceCapable
@EmbeddedOnly
public static class InnerTest{
@Persistent
private String whatever;
public InnerTest(){
whatever = "whatever";
}
}
public Test(){ }
public void addSomeInnerTests(){
innerTests = new ArrayList<InnerTest>();
for(int i = 0; i < 5; ++i)
innerTests.add(new InnerTest());
}
public List<InnerTest> getInnerTests(){
return innerTests;
}
}
and then I use the following testcode to save and retrieve the objects
// For saving
Test test = new Test();
test.addSomeInnerTests();
Test saved = pm.makePersistent(test);
System.out.println("persisted Test innerTests size = " +
saved.getInnerTests().size());
System.out.println("Saved Test key = " + saved.getKey());
// For retrieving
Query query = pm.newQuery(Test.class);
List<Test> list = (List<Test>)query.execute();
System.out.println("Tests = " + list.size());
for(Test test : list){
System.out.println("Retrieved Test key = " + test.getKey());
List<InnerTest> innerTests = test.getInnerTests();
System.out.println("innerTests size = " + innerTests.size());
}
and this provides the following output
persisted Test innerTests size = 5
Saved Test key = agtib2xsdHJvbGxlbnIMCxIEVGVzdBjbsAEM
Tests = 1
Retrieved Test key = agtib2xsdHJvbGxlbnIMCxIEVGVzdBjbsAEM
innerTests size = 0
So, why is the List in the retrieved Test empty? I have tried
retrieving an object directly as well, but this naturally leads to an
IndexOutOfBounds.
In my real code, all the other variables are saved and retrieved
properly. I have Lists of Strings and such as well, and they work just
fine, so its definitely related to children/embedded objects.
Any help is appreciated.
Thanks / Andreas
On 23 Dec, 07:32, "Ikai L (Google)" <[email protected]> wrote:
> Embedded objects should be eager loaded with any SDK version 1.2.8+ and
> above. Is this the version you are on? It's only child objects that are not
> eager loaded now.
>
> On Tue, Dec 22, 2009 at 3:15 PM, andreas_b <[email protected]>wrote:
>
>
>
> > Hi all.
>
> > I'm struggling a bit with default fetch groups in one of my entities
> > here..
>
> > Basically I have something that looks like this
>
> > @PersistenceCapable(identityType = IdentityType.APPLICATION,
> > detachable="true")
> > public class A {
>
> > �...@persistent(defaultFetchGroup = "true")
> > private List<B> embeddedObjects;
>
> > �...@persistencecapable(detachable="true")
> > �...@embeddedonly
> > public static class B {
> > ....
> > }
> > }
>
> > I want the list of my B objects to be fetched automatically when I
> > retrieve A from the datastore. This does not work however. It still
> > seems to do lazy loading and I get the following warning:
>
> > 2009-dec-22 23:57:52 org.datanucleus.store.appengine.MetaDataValidator
> > warn
> > WARNING: Meta-data warning for A.embeddedObjects: The datastore does
> > not support joins and therefore cannot honor requests to place child
> > objects in the default fetch group. The field will be fetched lazily
> > on first access..."
>
> > The above works fine if I change it to just: private B object, so the
> > problem seems related to List or collections in general. I have been
> > trying to find some explanation on this both in datanucleus docs and
> > here, but have been unable to find it.
>
> > Oh, and I can't use the "touch" technique since I use generic object
> > retrieval and that code has no knowledge of what the class contains,
> > and I want to keep it that way.
>
> > Could someone explain how this works (or point me to someplace) and
> > how I can solve it?
>
> > Thanks in advance.
>
> > BR, Andreas
>
> > --
>
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> > To post to this group, send email to
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>
> --
> Ikai Lan
> Developer Programs Engineer, Google App Engine
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