lazy initiallization of collections

tortenegger · **Joined:** Wed Jun 16, 2004 8:26 am **Posts:** 19

Hi all,

i have a problem working with lazy initiallization on collections.

I tried to use a proxy in my mapping file (same class) and
i tried to work with Hibernate.initialize(); at different places on my java-files.

Could someone tell me where change my source-code or mapping to get the lazy-thing working?

here my files i'm working with in a struts-web-environment.

Action_detail_isb_view.java

Code:

public class Action_detail_isb_view extends Action {

   public ActionForward execute(
      ActionMapping mapping,
      ActionForm form,
      HttpServletRequest request,
      HttpServletResponse response)
      throws IOException, ServletException, HibernateException {

      FormBean_detail_isb insertForm = (FormBean_detail_isb) form;

      Integer idUpdateIsb = new Integer(insertForm.getIdUpdateIsb());
      Bean_Update_ISB detail_isb =
         HibernateQueryUtil.loadUpdate_isb(idUpdateIsb);

...
         
      Integer changeRequest = detail_isb.getChangeRequest();

      Integer testTrack = detail_isb.getTestTrack_Nr();
      Set List_Update = detail_isb.getList_Update(); 
      
...
      request.setAttribute("listeUpdate", List_Update);

      return (mapping.findForward("success"));
   }
}

HibernateUtil.java --> from the official docs

Code:

   public class HibernateUtil {

      private static final SessionFactory sessionFactory;
      static {
         try {
            sessionFactory =
               new Configuration().configure().buildSessionFactory();
         } catch (HibernateException ex) {
            throw new RuntimeException(
               "Exception building SessionFactory: " + ex.getMessage(),
               ex);
         }
      }

      public static final ThreadLocal session = new ThreadLocal();


      public static Session currentSession() throws HibernateException {
         Session s = (Session) session.get();
         //      Open a new Session, if this Thread has none yet
         if (s == null) {
            s = sessionFactory.openSession();
            session.set(s);
         }
         return s;
      }

      public static void closeSession() throws HibernateException {
         Session s = (Session) session.get();
         session.set(null);
         if (s != null)
            s.close();
      }
   }

HibernateQueryUtil --> my own helper-class

Code:

   public static Bean_Update_ISB loadUpdate_isb(Integer id)
      throws IOException, ServletException, HibernateException {

      Session hibernate_session = HibernateUtil.currentSession();
      Transaction tx = hibernate_session.beginTransaction();
      Bean_Update_ISB update_isb = new Bean_Update_ISB();

      try {
         tx = hibernate_session.beginTransaction();

         update_isb =
            (Bean_Update_ISB) hibernate_session.load(
               Bean_Update_ISB.class,
               id);
         tx.commit();

      } catch (Exception e) {
         e.printStackTrace(System.err);
         if (tx != null)
            tx.rollback();
      } 
      finally {
         HibernateUtil.closeSession();
      }
      return update_isb;
   }

finally my mapping-file

Code:

<hibernate-mapping>
    <class name="com.tecdoc.db_update.Bean_Update_ISB" 
          table="t_Update_ISB">
           
        <id name="id_Update_ISB" column="id_Update_ISB" type="integer">
            <generator class="identity">
            </generator>
        </id>

        <property name="Datum"
                column="Datum"
                type="java.lang.String"/>

        <property name="Bezeichnung"
                column="Bezeichnung"
                type="java.lang.String"/>

        <property name="Pfadangabe_Speicherort"
                column="Pfadangabe_Speicherort"
                type="java.lang.String"/>

        <property name="ChangeRequest"
                column="ChangeRequest"
                type="integer"/>

        <property name="TestTrack_Nr"
                column="TestTrack_Nr"
                type="integer"/>
           
        <set name="List_Update" inverse="true" lazy="true">
           <key column="id_Update_ISB"/>
              <one-to-many class="com.tecdoc.db_update.Bean_Update"/>
          </set>
    </class>
</hibernate-mapping>

I always get
net.sf.hibernate.LazyInitializationException:
Failed to lazily initialize a collection - no session or session was closed

Thanks in advance.

toastchee · **Joined:** Fri Mar 26, 2004 8:19 am **Posts:** 49

IF I understand your question correctly, while your session is still open, all you have to do is call Hibernate.initialize(update_isb.getList_Update()).

tortenegger · **Joined:** Wed Jun 16, 2004 8:26 am **Posts:** 19

i think that's what i needed.
simple but i haven't done the initialisation correctly.

it seems to work

thx for your help.

often (especially for beginners) an obvious tip is really important cause not all aspects have a concrete example in the docs.

anthony · **Posted:** Wed Jul 21, 2004 3:07 am

but you have everything in Hibernate in Action

tortenegger · **Joined:** Wed Jun 16, 2004 8:26 am **Posts:** 19

but this book isn't released yet.

i only have one chapter that's free for download.

anthony · **Posted:** Wed Jul 21, 2004 3:16 am

you can buy it on meap.... ;))

toastchee · **Joined:** Fri Mar 26, 2004 8:19 am **Posts:** 49

I bought it on meap and it is great. Highly recommended.