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

[Kahli Burke (JIRA)]

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

Kahli Burke updated JBSEAM-1215:
--------------------------------

    Description: 
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;

    }

  was:
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 subsequence 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;

    }


> <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
>
> 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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