Hi, Entities that you persist in the datastore are grouped in so called entity groups for reason of scalability and transactionality
That means that the ds groups your entities on various data servers according to their keys: this mechanism is not transparent -> it generates the exception that you encounter when you touch entities belonging to more than 1 group in a single transaction. This mechanism is specific to GAE: it means that it is not transparent when you migrate the source code an already existing JPA app. You may have to rethink your data architecture and modify code accordingly. You should read the dev docs and articles: 1) http://code.google.com/appengine/docs/python/datastore/keysandentitygroups.html#Entity_Groups_Ancestors_and_Paths 2) http://code.google.com/appengine/docs/java/datastore/transactions.html 3) http://blog.dantup.com/2010/01/app-engine-entity-groups-contention-and-transactions 4) http://hoangle.info/2010/08/01/datastore-in-google-app-engine-entity-groups/ hope it helps On Nov 10, 10:37 am, lp <lucio.picc...@gmail.com> wrote: > hi all, > > i have been attempting to convert my existing JPA code over to GAE. > > All is working so far except for the unit tests. > > i read > code.google.com/appengine/docs/java/tools/localunittesting.html > > but it doesnt describe how to get an entityManager involved in usefull > unit tests. > > so this is my test. please advise how to achieve the functionality in > this test. > > @Test > public void findFriendsSimple() { > > PositionUser user1 = new PositionUser(); > user1.setFirstName("john"); > user1.setLastName("smith"); > > PositionUser user2 = new PositionUser(); > user2.setFirstName("mary"); > user2.setLastName("smith"); > > PositionUser user3 = new PositionUser(); > user3.setFirstName("barney"); > user3.setLastName("smith"); > > em.persist(user2); > em.persist(user3); > //em.flush(); <--- can use flush for non transaction test > > user1.getFriends().add(user2.getKey()); > user1.getFriends().add(user3.getKey()); > > em.persist(user1); > //em.flush(); <--- can use flush for non transaction test > > Query query = em.createNamedQuery(PositionUser.FIND_FRIENDS); > query.setParameter("userKey", user1.getKey()); > List resultList = query.getResultList(); > assertEquals( 2, resultList.size() ); > > } > > the assert is triggered > java.lang.AssertionError: expected:<2> but was:<0> > > this is because the entitymanager wont detect the persisted entities > that arent in a transaction. > > ok no problem, i will add transactions. > > But when i do it complains that i am adding multiple groups in a single > transaction. > > So besides the simple gae sample unit test, how are others writting > useful unit tests in gae? > > any help is most appreciated > > -lp -- 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. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
