please see https://issues.apache.org/jira/browse/TAP5-2027
  ----- Original Message ----- 
  From: Lenny Primak 
  To: Tapestry development 
  Sent: Wednesday, November 14, 2012 1:21 AM
  Subject: Re: PATCH: tapestry-jpa EntityManagerObjectProvider fixes entities 
not associated with correct entity manager issue


  I didn't look at this in detail, but proxies are sometimes thread-local, and 
not really singletons.
  Also, your patch isn't a real patch.  it's a replacement, and harder to 
incorporate for committers,
  if it is indeed necessary.

  On Nov 13, 2012, at 8:09 PM, John wrote:

  > Hi,
  > 
  > The original code is like below, note how the proxy provided acts like a 
singleton. I'll take a look at the JIRA, thanks.
  > 
  > public class EntityManagerObjectProvider implements ObjectProvider
  > {
  >    private EntityManager proxy;
  >    public <T> T provide(final Class<T> objectType, final AnnotationProvider 
annotationProvider,
  >            final ObjectLocator locator)
  >    {
  >        if (objectType.equals(EntityManager.class))
  >            return objectType.cast(getOrCreateProxy(annotationProvider, 
locator));
  >        return null;
  >    }
  > 
  >    private synchronized EntityManager getOrCreateProxy(
  >            final AnnotationProvider annotationProvider, final ObjectLocator 
objectLocator)
  >    {
  >        if (proxy == null)
  >        {
  >          ...
  >        }
  >        return proxy;
  >  ----- Original Message ----- 
  >  From: Lenny Primak 
  >  To: Tapestry development 
  >  Cc: <dev@tapestry.apache.org> 
  >  Sent: Wednesday, November 14, 2012 12:52 AM
  >  Subject: Re: PATCH: tapestry-jpa EntityManagerObjectProvider fixes 
entities not associated with correct entity manager issue
  > 
  > 
  >  I am not sure why the existing code doesn't work for you as it works fine 
in my environment. 
  >  Another thing is that patches belong in JIRA and cannot be taken from 
mailing lists due to copyright issues. 
  > 
  >  Perhaps Igor can shed some light on this?
  > 
  >  On Nov 13, 2012, at 7:48 PM, "John" <j...@quivinco.com> wrote:
  > 
  >> I put this on the users group recently to complete a thread, it belongs 
here really I suppose.
  >> 
  >> The problem manifests when multiple PUs are defined in persistence.xml and 
then referred to in classes using the @PersistenceContext(unitName= annotation. 
As it is in 5.3.6 the first EntityManager wired up gets injected to all 
successive EntityManager instances and the unitName= value is ignored. Probem 
was caused by reusing a class variable. The bug makes it seem that entities are 
not wired to the EntityManager as you would expect, in fact the reference 
passed in is bad.
  >> 
  >> Also refactored to use PlasticProxyFactory.
  >> 
  >> John
  >> 
  >> 
  >> ----- Original Message ----- From: John
  >> To: Tapestry users
  >> Sent: Tuesday, November 13, 2012 7:51 AM
  >> Subject: PATCH: tapestry-jpa EntityManagerObjectProvider fixes entities 
not associated with correct entity manager issue
  >> 
  >> 
  >> This looks like a bug where a class member variable is used to cache the 
EntityManager that is subsequently handed to all the PersistenceContext 
annotations regardless of the unitName, like I said.
  >> 
  >> The following replacement class is tested working and handles multiple 
persistence units correctly as per the original Tapestry docs, just put it on 
your classpath first. Maybe someone on the developer side can check this out 
and commit it to the build cycle.
  >> 
  >> 
  >> package org.apache.tapestry5.internal.jpa;
  >> 
  >> import javax.persistence.EntityManager;
  >> import javax.persistence.PersistenceContext;
  >> 
  >> import org.apache.tapestry5.ioc.AnnotationProvider;
  >> import org.apache.tapestry5.ioc.ObjectCreator;
  >> import org.apache.tapestry5.ioc.ObjectLocator;
  >> import org.apache.tapestry5.ioc.ObjectProvider;
  >> import org.apache.tapestry5.ioc.services.PlasticProxyFactory;
  >> import org.apache.tapestry5.jpa.EntityManagerManager;
  >> 
  >> /**
  >> * A patched version to use PlasticProxyFactory and not cache the 
EntityManager as a class member.
  >> * @author John Coleman
  >> */
  >> public class EntityManagerObjectProvider implements ObjectProvider
  >> {
  >> 
  >>  /**
  >>   * {@inheritDoc}
  >>   */
  >>  public <T> T provide(final Class<T> objectType, final AnnotationProvider 
annotationProvider,
  >>          final ObjectLocator locator)
  >>  {
  >>      if (objectType.equals(EntityManager.class))
  >>          return objectType.cast(getOrCreateProxy(annotationProvider, 
locator));
  >> 
  >>      return null;
  >>  }
  >> 
  >>  private synchronized EntityManager getOrCreateProxy(
  >>          final AnnotationProvider annotationProvider, final ObjectLocator 
objectLocator)
  >>  {
  >>          final PlasticProxyFactory proxyFactory = 
objectLocator.getService("PlasticProxyFactory",
  >>            PlasticProxyFactory.class);
  >> 
  >>           final PersistenceContext annotation = annotationProvider
  >>                          .getAnnotation(PersistenceContext.class);
  >> 
  >>          EntityManager proxy = 
proxyFactory.createProxy(EntityManager.class, new ObjectCreator<EntityManager>()
  >>          {
  >>              public EntityManager createObject()
  >>              {
  >>                  final EntityManagerManager entityManagerManager = 
objectLocator
  >>                          .getService(EntityManagerManager.class);
  >> 
  >>                  return 
JpaInternalUtils.getEntityManager(entityManagerManager, annotation);
  >>              }
  >>          }, "<EntityManagerProxy>");
  >> 
  >>      return proxy;
  >>  }
  >> 
  >> } 
  >> 
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