[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-6960) NullPointerException in PreCollectionRemove Listener

[ms (JIRA)]

    [ https://hibernate.onjira.com/browse/HHH-6960?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=46295#comment-46295 ] 

ms commented on HHH-6960:
-------------------------

I too have the same issue.  Unable to recreate in unit test but able to in live run.

Couple of notes on my entity:
- not audited, nor directly related to audited entites.
- the offending entity collection is a child of the entity that's being persisted.
- collection entity class has 3 items related back to it through oneToMany relationships.  Their definition is as follows:

    @OneToMany(mappedBy = "sourceField", fetch = FetchType.EAGER)
    private List<TableMapplet> sourceMapplets;
    @OneToMany(mappedBy = "targetField", fetch = FetchType.EAGER)
    private List<Mapplet> targetMapplets;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "column", fetch = FetchType.EAGER)
    private List<IndexColumn> indexColumns;

What is occurring in hibernate in steps:

1) "org.hibernate.engine.spi.ActionQueue#executeActions()" is executing "executeActions( collectionRemovals );" where "collectionRemovals" has 15 items...  its those 3 relationship owning entities, mentioned earlier, repeated over and over again. so cycling through 5 five times.  These actions are executed by the private "executeActions()" method.
2) "org.hibernate.action.internal.CollectionRemoveAction#preRemove()" creates the event object.  It is here where "getPersister()" is called in event constructor to add the appropriate "loadedPersister" then executes the listener.
3) "org.hibernate.envers.event.EnversPreCollectionRemoveEventListenerImpl#onPreRemoveCollection()" called by (step 2) where it checks for loadedPersister (loaded previously) and determines if inverse, which is false and continues on for all 3 varying items.

So what is stumping me is that on the 4th iteration the same getPersister() object from the 1st iteration is used in the event constructor (step 2 from above).  All is good.  However, when the code moves into (step 3) "onPreRemoveCollection()" getLoadedPersister() returns null.

I don't see anything in collectionRemoveAction nor in ActionQueue that could remove it and obviously it had the object in the 4th iteration.  As per the enver's side only the listener is called as far as i can tell, so no clean up job to follow unless there's some weaving going on that i don't see.

Any help in resolving this issue would greatly be appreciated. Its a showstopper for me.


> NullPointerException in PreCollectionRemove Listener
> ----------------------------------------------------
>
>                 Key: HHH-6960
>                 URL: https://hibernate.onjira.com/browse/HHH-6960
>             Project: Hibernate ORM
>          Issue Type: Bug
>          Components: envers
>    Affects Versions: 4.0.0.Final
>         Environment: Hibernate 4.0.0 to MySQL
>            Reporter: Kevin Jordan
>            Assignee: Adam Warski
>
> I'm getting a NullPointerException on line 47 of EnversPreCollectionRemoveEventListenerImpl very consistently. I wasn't sure if it was due to lazy collections or not, but it seems that it fails if they're eagerly fetched or lazily fetched. I'm guessing it has something to do with getLoadedPersister() returning a null value since the comments for it say "This is only available late during the flush cycle". The stack trace is
> Quote:
> java.lang.NullPointerException
> at org.hibernate.envers.event.EnversPreCollectionRemoveEventListenerImpl.onPreRemoveCollection(EnversPreCollectionRemoveEventListenerImpl.java:47)
> at org.hibernate.action.internal.CollectionRemoveAction.preRemove(CollectionRemoveAction.java:143)
> at org.hibernate.action.internal.CollectionRemoveAction.execute(CollectionRemoveAction.java:104)
> at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:273)
> at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:265)
> at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:188)
> at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:323)
> at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:52)
> at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1081)
> at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:315)
> at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.beforeTransactionCommit(JdbcTransaction.java:101)
> at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.commit(AbstractTransactionImpl.java:175)
> at org.hibernate.ejb.TransactionImpl.commit(TransactionImpl.java:73)
> ... 120 more

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