Hello Thomas, Open Session In View is the right approach to go for. Thank you for this advice! I have implemented it and it works fine now.
However, I have one question regarding OSIV-Pattern: In the Hybernate example (see link below) they *begin transaction* before doFilter() and *commit on transaction* after it. https://community.jboss.org/wiki/OpenSessionInView I am using standard GWT setting with DataNucleus. For some reason it does not let me call em.getTransaction().begin(); and em.getTransaction().commit(); within the filter. In my current implementation I can *create EntityManager* before doFilter() and *close it* afterwards (this works), but cannot commit nor rollback transaction Here is the error which I get when trying to open and commit the transaction: org.datanucleus.exceptions.NucleusFatalUserException: Illegal argument .... Caused by: java.lang.IllegalArgumentException: cross-group transaction need to be explicitly specified, see TransactionOptions.Builder.withXGfound both Element { type: "JobCategory" id: 1 } and Element { type: "JobCategory" id: 13 } Do you have any Idea what might be the reason? It must probably have something to do with my persistence.xml settings: <persistence-unit name="emajstor_persistence"> ... some Entities <exclude-unlisted-classes>true</exclude-unlisted-classes> <properties> <property name="datanucleus.NontransactionalRead" value="true"/> <property name="datanucleus.NontransactionalWrite" value="true"/> <property name="datanucleus.ConnectionURL" value="appengine"/> </properties> </persistence-unit> Thank you in advance: Nermin Am Donnerstag, 13. Juni 2013 15:05:56 UTC+2 schrieb Thomas Broyer: > > > > On Thursday, June 13, 2013 2:57:02 PM UTC+2, Nermin wrote: >> >> Hello group, >> >> Is the issue 6115 Fixed in GWT 2.5 or not?? >> http://code.google.com/p/google-web-toolkit/issues/detail?id=6115 >> >> My problem is that on a entity with recursive relation the ancestors are >> not loaded when calling with(ancestors). >> >> Here is my code: >> >> @Entity >> public class *JobCategory *{ >> // -- Recursive Relation mainCategory - SubCategories >> @*OneToMany*(mappedBy = "mainCategory", cascade = CascadeType.ALL) >> private Set<*JobCategory*> *subCategories *= new >> HashSet<JobCategory>(); >> @ManyToOne >> private *JobCategory *mainCategory; >> >> ... Getters / Setters >> >> public static List<JobCategory> findAllJobCategories() { >> EntityManager em = EMFService.get().createEntityManager(); >> try { >> Query query = em.createQuery("SELECT e FROM "+ >> JobCategory.class.getSimpleName() + " e ORDER BY i18nKey"); >> return (List<JobCategory>) query.getResultList(); >> } catch (Exception e) { >> e.printStackTrace(); >> } finally { >> em.close(); >> } >> return new ArrayList<JobCategory>(); // Return empty list. >> } >> } >> >> >> When I call: >> JobCategoryRequest jobCategoryReq = >> this.requestFactory.jobCategoryRequest(); >> Request<List<JobCategoryProxy>> req = >> jobCategoryReq.findAllJobCategories().with("*subCategories*"); >> req.fire(receiver); >> >> ... The call will return categories but without subcatgeories. (The list >> is always empty). >> I checked the DB, it is all fine there. >> >> Can it be that the Bug 6115 has not been fixed, even though its status >> says so, or am I doing something wrong here? >> > > Have you checked whether the caller is called? if it is, does it return a > populated set? > > You're supposed to use an open-session-in-view (aka session-per-request) > pattern with RequestFactory, rather than creating/closing an EntityManager > in each service method. In this simple example (a single service method > call in the RequestContext, with no shared object between the request > –arguments– and the response), it shouldn't cause any harm *except* if > you lazy-load your linked entities. > -- You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group. To unsubscribe from this group and stop receiving emails from it, send an email to google-web-toolkit+unsubscr...@googlegroups.com. To post to this group, send email to google-web-toolkit@googlegroups.com. Visit this group at http://groups.google.com/group/google-web-toolkit. For more options, visit https://groups.google.com/groups/opt_out.
