[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-3062) Incompleted Collection Returned from Joined Fetch

[Christian Wasel (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-3062?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=31492#action_31492 ] 

Christian Wasel commented on HHH-3062:
--------------------------------------

I also had this error. I analyzed the code and found out the following:

The error appeares when using a HQL query with a JOIN FETCH or LEFT JOIN FETCH and the joined entity is mapped with @OneToMany and has an embedded id.
My @OneToOne mappings work fine using FETCH with a simple id and also an embedded id. 
Also @OneToMany mappings work fine using FETCH when I have just a simple id.


I looked inside the code but wasn't able to find a concrete cause. As starting point for a possible problem I identified the following method in the AbstractEntityTuplizer class:

	public void setIdentifier(Object entity, Serializable id) throws HibernateException {
		if ( entityMetamodel.getIdentifierProperty().isEmbedded() ) {
			if ( entity != id ) {
				AbstractComponentType copier = (AbstractComponentType) entityMetamodel.getIdentifierProperty().getType();
				copier.setPropertyValues( entity, copier.getPropertyValues( id, getEntityMode() ), getEntityMode() );
			}
		}
		else if ( idSetter != null ) {
			idSetter.set( entity, id, getFactory() );
		}
	}

When I followed the methods "entityMetamodel.getIdentifierProperty().isEmbedded()" up to the AnnotationBinder class it seemded that the "isEmbedded()" method will always return false. Even If the entity variable contains an entity with an embedded id class. (Note: I saw the "PersistenceClass" container class containes an inner container "IdentifiedProperty" with contains an EmbeddedContainerType but the embedded flag is false!)
So if I'm right the first if-clause is never entered and for entities with embedded ids the values are never set. And how can later the values be set at all elements of the collection if the single element cannot be identified by the id (cause this variable is still null)? Maybe that's a starting point for the failure search.




> Incompleted Collection Returned from Joined Fetch
> -------------------------------------------------
>
>                 Key: HHH-3062
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-3062
>             Project: Hibernate Core
>          Issue Type: Bug
>          Components: query-hql
>    Affects Versions: 3.2.5
>         Environment: Windows XP SP2, JDK 1.6_03, MySQL 5, Toncat 5.5.25
>            Reporter: Tony Lin
>         Attachments: org.zip, subsets.sql
>
>
> Executing the following query:
> select subset from com.alphait.domain.snomed.object.SubsetImpl as subset join fetch subset.members as members left join fetch members.parent
> The members returned after the first subset are not complete, all but the first member are missing.
> The classes are attached in HHH-3056. The test data is in the attached file, please load it to a mysql database.
> After investigation, the problem seems be in Loader.java's sequentialLoad method:
> 		try {
> 			do {
> 				Object loaded = getRowFromResultSet(
> 						resultSet,
> 						session,
> 						queryParameters,
> 						getLockModes( queryParameters.getLockModes() ),
> 						null,
> 						hydratedObjects,
> 						loadedKeys,
> 						returnProxies
> 					);
> 				if ( result == null ) {
> 					result = loaded;
> 				}
> 			} 
> 			while ( keyToRead.equals( loadedKeys[0] ) && resultSet.next() );
> 		}
> 		catch ( SQLException sqle ) {
> 			throw JDBCExceptionHelper.convert(
> 			        factory.getSQLExceptionConverter(),
> 			        sqle,
> 			        "could not perform sequential read of results (forward)",
> 			        getSQLString()
> 				);
> 		}
> 		initializeEntitiesAndCollections( 
> 				hydratedObjects, 
> 				resultSet, 
> 				session, 
> 				queryParameters.isReadOnly() 
> 			);
> 		session.getPersistenceContext().initializeNonLazyCollections();
> 		return result;
> It will fetch the next subset also, but only the first member, and the member's parent. These three are hydrated, and resolved when initializeEntitiesAndCollections is called.
> This makes the members collection to be freezed, and no member can be added.
> We put the following:
>     key = getKeyFromResultSet(
> 					        0,
> 							persisters[0],
> 							null,
> 							resultSet,
> 							session
> 						);
> 				
>     if (!keyToRead.equals(key)) { // we are done, no moving forward
> 	break;
>     }
> 			
> before calling getRowFromResultSet(). This temporarily solved the problem for us.
> Also this kind of query cannot have order by containing only the members'  properties as it will return rows not ordered by Subset's ID. I think the HQL query parser should not permit this. 	

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