[hibernate-issues] [Hibernate-JIRA] Issue Comment Edited: (HHH-6349) AuditJoinTable rows missing when detached entities with collections are merged into the persistence context

[Xi Zhang (JIRA)]

    [ https://hibernate.onjira.com/browse/HHH-6349?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=45390#comment-45390 ] 

Xi Zhang edited comment on HHH-6349 at 2/7/12 8:00 AM:
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I have the same problem on usage of the (unidirectional)OneToMany annotation like described above. As I also tried the another possiblity to audit the OneToMany by using a "fake" bidirectional reference with the annotation @AuditMappedBy, I got nearly same result, instead of missing entry in the AuditJoinTable I had the Null-values in the join column.

As a workaround  I defined a real bidirectional relation(OneToMany +ManyToOne) between the entities, then I can audit the entities updates correctly.

Is it the reason? that the missing ManyToOne reference or the (updatable=false) "fake" ManyToOne relation is merged/updated from detached entities to attached entities as the merge() method's semantic defined in JPA specification.

The (unidirectional)OneToMany annotation is the critical path in the ENVERS.

JPA Specifiction 1.0
{code}
3.2.4.1 Merging Detached Entity State

If X is a detached entity, the state of X is copied onto a pre-existing managed entity instance X'
of the same identity or a new managed copy X' of X is created.
{code}

      was (Author: xi.zhang):
    I have the same problem on usage of the (unidirectional)OneToMany annotation like described above. As I also tried the another possiblity to audit the OneToMany by using a "fake" bidirectional reference with the annotation @AuditMappedBy, I got nearly same result, instead of missing entry in the AuditJoinTable I had the Null-values in the join column.

As a workaround  I defined a real bidirectional relation(OneToMany +ManyToOne) between the entities, then I can audit the entities updates correctly.

Is it the reason, that the "fake" ManyToOne relation that is private(updatable=false) could not be merged/updated from detached entities to attached entities as the merge() method's semantic defined in JPA specification.

I think, the (unidirectional)OneToMany annotation is the critical path in the ENVERS.
  
> AuditJoinTable rows missing when detached entities with collections are merged into the persistence context
> -----------------------------------------------------------------------------------------------------------
>
>                 Key: HHH-6349
>                 URL: https://hibernate.onjira.com/browse/HHH-6349
>             Project: Hibernate ORM
>          Issue Type: Bug
>          Components: envers
>    Affects Versions: 3.6.5, 4.0.0.Beta1
>            Reporter: Erik-Berndt Scheper
>            Assignee: Erik-Berndt Scheper
>
> Given an Entity that is audited by Envers, which contains more than one collection (e.g. two Lists); for example
> {code:title=MultipleCollectionEntity .java|borderStyle=solid}
> Entity
> @org.hibernate.envers.Audited
> public class MultipleCollectionEntity {
> 	@Id
> 	@GeneratedValue(strategy = GenerationType.IDENTITY)
> 	@Column(name = "ID", length = 10)
> 	private Long id;
> 	@Version
> 	@Column(name = "VERSION", nullable = false)
> 	private Integer version;
> 	@Column(name = "TEXT", length = 50, nullable = false)
> 	private String text;
> 	@OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL, orphanRemoval = true)
> 	@JoinColumn(name = "MCE_ID", nullable = false)
> 	@org.hibernate.envers.AuditJoinTable(name = "MCE_RE1_AUD", inverseJoinColumns = @JoinColumn(name = "RE1_ID"))
> 	private List<MultipleCollectionRefEntity1> refEntities1 = new ArrayList<MultipleCollectionRefEntity1>();
> 	@OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL, orphanRemoval = true)
> 	@JoinColumn(name = "MCE_ID", nullable = false)
> 	@org.hibernate.envers.AuditJoinTable(name = "MCE_RE2_AUD", inverseJoinColumns = @JoinColumn(name = "RE2_ID"))
> 	private List<MultipleCollectionRefEntity2> refEntities2 = new ArrayList<MultipleCollectionRefEntity2>();
> {code}
> Envers stores the audit information for additions and deletions to these Lists in AuditJoinTables (MCE_RE1_AUD and MCE_RE2_AUD). This process is driven by the Hibernate collection events; to be exact by the difference between the current contents of the collection (using event.getCollection()) and the contents of the stored snapshot of this collection (using collectionEntry.getSnapshot()).
> This works fine as long as the given entity is available in the current persistence context. 
> Unfortunately, this is not the case when detached entities are merged back into the persistence context. 
> In this case, the end result is that audit information is stored in the MultipleCollectionEntity_AUD table, in the MultipleCollectionRefEntity1_AUD table and the MultipleCollectionRefEntity2_AUD table. However, the AuditJoinTable rows are missing. 
> Effectively this means that the rows in MultipleCollectionRefEntity2_AUD are dangling and that the audit information when refEntities were added or deleted to the refEntities1 and refEntities2 collections has been irretrievably lost.
> I have prepared Envers test cases for the 3.6.x and 4.0.x versions and will be adding them shortly.

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