[jbossseam-issues] [JBoss JIRA] Resolved: (JBSEAM-1215) <s:convertEntity> / org.jboss.seam.ui.EntityConverter fails to return correct id when entity is wrapped Hibernate proxy (JavassistLazyInitializer)

Pete Muir (JIRA) jira-events at lists.jboss.org
Fri Apr 20 06:09:30 EDT 2007

     [ http://jira.jboss.com/jira/browse/JBSEAM-1215?page=all ]

Pete Muir resolved JBSEAM-1215.

    Fix Version/s: 1.3.0.BETA1
       Resolution: Out of Date
         Assignee: Pete Muir

Significant refactoring in CVS post 1.2.1 has occurred such that if Hibernate is the peristence layer used then we delegate to session.getIdentifier().  This gives accurate reporting of an Id. (if you aren't using hibernate, you are stuck on scanning for the method or field annotated with @Id using Reflection)

Please test using current CVS, and reopen if doesn't work! Thanks :)

> <s:convertEntity> / org.jboss.seam.ui.EntityConverter fails to return correct id when entity is wrapped Hibernate proxy (JavassistLazyInitializer)
> --------------------------------------------------------------------------------------------------------------------------------------------------
>                 Key: JBSEAM-1215
>                 URL: http://jira.jboss.com/jira/browse/JBSEAM-1215
>             Project: JBoss Seam
>          Issue Type: Bug
>          Components: JSF
>    Affects Versions: 1.2.1.GA
>         Environment: JBoss Seam 1.2.1, JBoss 4.0.5GA, Hibernate 3.2.1, JSF RI 1.2, Facelets 1.1.12
>            Reporter: Kahli Burke
>         Assigned To: Pete Muir
>             Fix For: 1.3.0.BETA1
> In certain circumstances the <s:entityConverter> handler org.jboss.seam.ui.EntityConverter will fail to return the correct id for the entity when getAsString() is called.  I have seen this occur when one of my components called entityManager.clear(), and then on a subsequent page load a query was made.  In this case, the actual object used in getIdFromEntity() was a proxied object.  The object was proxied by Hibernate's JavassistLazyInitializer.
> The getIdFromEntity() method looks for a field annotated with @Id, which this entity has (we are using field annotations as opposed to method annotations), and then attempts to get the id from the object using direct field access (through Reflections.get(field, entity)).  Because the object is wrapped, this returns the default value for the class.  In my case it returns 0 for the id since this entity uses a long for the id field.  
> If the getter method had been called instead, the correct non-zero value would have been returned.  And usually, this works because the object is an actual instance of the entity class and has the correct value for the field.
> My workaround for now is to create a subclass of EntityConverter (and using the very useful @Install precedence, thank you!) that calls the superclass' implementation and in cases where it looks like it might be incorrect, looks for a getter method and calls that instead.  There is probably a better way to do it, but I'm not familiar with the Hibernate proxies or how to properly get at the underlying object.
>     @Override
>     protected Object getIdFromEntity(UIComponent cmp, FacesContext facesContext, Object entity, Class entityClass) {
>         Object id = super.getIdFromEntity(cmp, facesContext, entity, entityClass);
>         // If the id looks like it came out incorrect from the field access
>         if ((id instanceof Number && ((Number) id).longValue() == 0) || (id == null)) {
>             List<Field> fields = Reflections.getFields(entityClass, Id.class);
>             if (fields.size() == 1) {
>                 Field field = fields.get(0);
>                 Method getter = null;
>                 try {
>                     getter = Reflections.getGetterMethod(entityClass, field.getName());
>                 }
>                 catch (IllegalArgumentException e) {
>                     if (log.isDebugEnabled())
>                         log.debug("Id #0 looked incorrect, but unable to find getter method for field #1", id, field.getName());
>                     return id;
>                 }
>                 if (getter != null) {
>                     try {
>                         id = Reflections.invoke(getter, entity);
>                     }
>                     catch (Exception e) {
>                         log.error("Error invoking getter method #0, returning original id #1", e, getter.getName(), id);
>                     }
>                 }
>             }
>         }
>         return id;
>     }

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