[Hibernate-issues] [Hibernate-JIRA] Commented: (HHH-1725) lazy properties, events and collection xxx was not processed by flush exception and EJB3 incompatibility

[Tomasz B. (JIRA) <no...@at...>]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-1725?page=comments#action_23052 ] 

Tomasz Bech commented on HHH-1725:
----------------------------------

I think there is small issue with current implementation (a bug?).
Scenario is:
object A has reference to B (lazy), B has collection C.
when in preInsert a.getB().getAnyProperty() is called the flush is raising exception 'collection b.c was not processed by flush()'.
(it is not rising exception like 'property b was not processed by flush()' - so the problem is only when there is lazy property which has at least ONE collection).

The collection C isn't even accessed, used, etc. The exception is to avoid situation of usage/modififcation of collection, and it isn't the case.
So shouldn't following function :
CollectionEntry:
public void postFlush(PersistentCollection collection) throws HibernateException {
		if ( isIgnore() ) {
			ignore = false;
		}
		else if ( !isProcessed() ) {
			throw new AssertionFailure( "collection [" + collection.getRole() + "] was not processed by flush()" );
		}
		collection.setSnapshot(loadedKey, role, snapshot);
	}

check also if collection was initialized? Like this:

public void postFlush(PersistentCollection collection) throws HibernateException {
		if ( isIgnore() ) {
			ignore = false;
		}
		else if (collection.wasInitialized() && !isProcessed() ) {
			throw new AssertionFailure( "collection [" + collection.getRole() + "] was not processed by flush()" );
		}
		collection.setSnapshot(loadedKey, role, snapshot);
	}

In this case the real (currently prohibited by Hibernate) usage of collections in flush will be reported.


> lazy properties, events and collection xxx was not processed by flush exception and EJB3 incompatibility
> --------------------------------------------------------------------------------------------------------
>
>          Key: HHH-1725
>          URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-1725
>      Project: Hibernate3
>         Type: Bug

>   Components: core
>     Versions: 3.2.0.cr2
>     Reporter: Tomasz Bech

>
>
> It is realted to anomaly: http://opensource.atlassian.com/projects/hibernate/browse/HHH-1540
> 'When using custom event listeners, sometimes you mess with (and initialize) lazy collections by mistake, which causes CollectionEntry.postFlush(PersistentCollection) to throw an AssertionFailure'
> It is questionable why AT ALL exception is raised in this case!
> What is the most important: EJB3 spec is not prohibiting to check/read/ object involved in the event, so current implementation is agains EJB3 spec.
> Events are often used for validation so it is quite probable that the lazy property (collection) has to be accessed - and when it is lazy and not initialized before the exception is raised. Why hibernate cannot treat it in nicer way and allow such actions. 
> One workaround is to not-use-lazy (very bad).
> Second workaround: in the code outside flush (not in event) pre-initialize all lazy properties (in fact simulation of 'not-lazy).

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