[jira] Issue Comment Edited: (CAMEL-2980) camel-jpa doesn't use EntityManager.merge(entity) in the right way

["Christian Mueller (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/activemq/browse/CAMEL-2980?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=60925#action_60925 ] 

Christian Mueller edited comment on CAMEL-2980 at 7/26/10 5:30 PM:
-------------------------------------------------------------------

Unfortunately not. I have fixed [CAMEL-2982|https://issues.apache.org/activemq/browse/CAMEL-2982] with the new 'usePersist' option. What I have to change for this issue is something like this:

is:
{code}
entityManager.merge(entity); 
{code}

shall:
{code}
Object managedEntity = entityManager.merge(entity);
exchange.getIn().setBody(managedEntity);
{code}

But this is not so trivial, because the input could be not only an annotated entity, it could also be a list, map, ... and in the current implementation we iterate over a collection (which may be only have one entry):

{code}
public void process(Exchange exchange) {
  exchange.getIn().setHeader(JpaConstants.JPA_TEMPLATE, endpoint.getTemplate());
  final Object values = expression.evaluate(exchange, Object.class);
  if (values != null) {
    template.execute(new JpaCallback() {
      public Object doInJpa(EntityManager entityManager) throws PersistenceException {
        Iterator iter = ObjectHelper.createIterator(values);
          Object value = iter.next();
          if (endpoint.isUsePersist()) {
            entityManager.persist(value);
          } else {
            entityManager.merge(value);
          }
        }
        if (endpoint.isFlushOnSend()) {
          entityManager.flush();
        }
        return null;
      }
    });
  }
  exchange.getIn().removeHeader(JpaConstants.JPA_TEMPLATE);
} 
{code}

Christian

      was (Author: muellerc):
    Unfortunately not. I have fixed [CAMEL-2982|https://issues.apache.org/activemq/browse/CAMEL-2982] with the new 'usePersist' option. What I have to change for this issue is something like this:

is:
{code}
entityManager.persist(entity); 
{code}

shall:
{code}
Object managedEntity = entityManager.persist(entity);
exchange.getIn().setBody(managedEntity);
{code}

But this is not so trivial, because the input could be not only an annotated entity, it could also be a list, map, ... and in the current implementation we iterate over a collection (which may be only have one entry):

{code}
public void process(Exchange exchange) {
  exchange.getIn().setHeader(JpaConstants.JPA_TEMPLATE, endpoint.getTemplate());
  final Object values = expression.evaluate(exchange, Object.class);
  if (values != null) {
    template.execute(new JpaCallback() {
      public Object doInJpa(EntityManager entityManager) throws PersistenceException {
        Iterator iter = ObjectHelper.createIterator(values);
          Object value = iter.next();
          if (endpoint.isUsePersist()) {
            entityManager.persist(value);
          } else {
            entityManager.merge(value);
          }
        }
        if (endpoint.isFlushOnSend()) {
          entityManager.flush();
        }
        return null;
      }
    });
  }
  exchange.getIn().removeHeader(JpaConstants.JPA_TEMPLATE);
} 
{code}

Christian
  
> camel-jpa doesn't use EntityManager.merge(entity) in the right way
> ------------------------------------------------------------------
>
>                 Key: CAMEL-2980
>                 URL: https://issues.apache.org/activemq/browse/CAMEL-2980
>             Project: Apache Camel
>          Issue Type: Bug
>          Components: camel-jpa
>    Affects Versions: 2.4.0
>         Environment: All
>            Reporter: Christian Mueller
>            Assignee: Christian Mueller
>             Fix For: 2.5.0
>
>
> The EntityManager.merge(entity) method returns the merged entity. The exchange in message body should be updated with the merged entity (what camel-jpa currently not do).
> I running into this problem, because after saving an entity in the database, the id field was still null. So, we don't know, which entity in the database is the corresponding to this entity... :-(
> Have a look in the process method of [JpaProducer|http://svn.apache.org/viewvc/camel/trunk/components/camel-jpa/src/main/java/org/apache/camel/component/jpa/JpaProducer.java?view=markup] and the Java doc from the [EntityManager|http://download.oracle.com/docs/cd/E17477_01/javaee/5/api/javax/persistence/EntityManager.html#merge%28T%29].
> Christian

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