If I recall, JDO is picky when it comes to being aware of changes made
to a persisted object. For example, changing fields directly
(object.field = newValue;) doesn't work - you need to use a getter/
setter (object.setField(newValue);). Perhaps you are encountering the
same issue here? Does the following type of thing work?
LIst<SubEntity> list = e.getMyList();
SubEntity first = list.remove(0);
list.add(first);
e.setMyList(list);
pm.makePersistent(e);
tx.commit();
Jake
On Feb 28, 11:05 am, Gunnar <gunnar....@gmail.com> wrote:
> Hi,
> John and Karel, you are right about the placement of the commit
> statement.
> It worked in the test example because I only had one instance of
> MyEntity.
> I don't get any exception at all in the Eclipse console!
> When I add a second instance of MyEntity if fails with "Transaction is
> not active" as expected.
>
> Now I've changed the code in the try statement like this, but still
> the first sub entity is lost and no exception is thrown!
> (Of cause it would fail it the list is empty.)
>
> List<MyEntity> results = (List<MyEntity>) query.execute();
> if (results.iterator().hasNext()) {
> tx.begin();
> MyEntity e = results.iterator().next();
> List<SubEntity> list = e.getMyList();
> SubEntity first = list.remove(0);
> boolean ok = list.add(first);
> if (!ok) {
> System.err.println("could not add first");
> }
> System.out.println(list);
> pm.makePersistent(e);
> tx.commit();
> }
>
> On 28 Feb, 02:51, John Patterson <jdpatter...@gmail.com> wrote:
>
> > This should be throwing an exception. The JavaDocs for
> > Transaction.commit() say
> > Commits the transaction. Whether this call succeeds or fails, all
> > subsequent method invocations on this object will throw
> > IllegalStateException.
>
> > When something does not work as you expect the first place to look is
> > the logs under your application console.
>
> > On 28 Feb 2010, at 05:25, Karel Alvarez wrote:
>
> > > dont you get any exceptions stacktrace in the server console? it
> > > would help... also you are calling commit() inside the for loop,
> > > although the transactions is started only once... that would crash
> > > in the second iteration in a normal db server, I am not sure what
> > > GAE does with it, in any case I dont think it is what you intended...
>
> > > On Sat, Feb 27, 2010 at 2:52 PM, Gunnar <gunnar....@gmail.com> wrote:
> > > Hi,
> > > I have problem with reordering a List.
> > > I created a test with an entity called MyEntity which have a
> > > List<SubEntity>.
> > > First I persist one instance of MyEntity with a list containing 3
> > > SubEntity.
> > > This works fine. Then I call a reorder servlet that moves the first
> > > SubEntity to the last position in the list.
> > > The result is that the first SubEntity is lost and the datastore only
> > > contains 2 SubEntity instances.
> > > What can be wrong?
> > > Here is the reorder code:
>
> > > package com.google.appengine.demo;
>
> > > import java.io.IOException;
> > > import java.util.List;
>
> > > import javax.jdo.PersistenceManager;
> > > import javax.jdo.Query;
> > > import javax.jdo.Transaction;
> > > import javax.servlet.http.HttpServlet;
> > > import javax.servlet.http.HttpServletRequest;
> > > import javax.servlet.http.HttpServletResponse;
>
> > > @SuppressWarnings("serial")
> > > public class ReorderServlet extends HttpServlet {
> > > �...@suppresswarnings("unchecked")
> > > public void doGet(HttpServletRequest req, HttpServletResponse
> > > resp)
> > > throws IOException {
> > > PersistenceManager pm =
> > > PMF.get().getPersistenceManager();
> > > Query query = pm.newQuery(MyEntity.class);
> > > Transaction tx = pm.currentTransaction();
> > > try {
> > > tx.begin();
> > > List<MyEntity> results = (List<MyEntity>)
> > > query.execute();
> > > if (results.iterator().hasNext()) {
> > > for (MyEntity e : results) {
> > > List<SubEntity> list =
> > > e.getMyList();
> > > SubEntity first =
> > > list.remove(0);
> > > boolean ok = list.add(first);
> > > if (!ok) {
>
> > > System.err.println("could not add first");
> > > }
> > > System.out.println(list);
> > > pm.makePersistent(e);
> > > tx.commit();
> > > }
> > > }
> > > } catch (Exception e) {
> > > e.printStackTrace();
> > > } finally {
> > > if (tx.isActive())
> > > tx.rollback();
> > > query.closeAll();
> > > pm.close();
> > > }
> > > resp.setContentType("text/plain");
> > > resp.getWriter().println("reordered");
> > > }
> > > }
>
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