[hibernate-issues] [Hibernate-JIRA] Created: (HHH-2626) Bug in handling null references to Components / Embeddables when using session / entityManager.merge()

[Michael Plöd (JIRA)]

Bug in handling null references to Components / Embeddables when using session / entityManager.merge()
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                 Key: HHH-2626
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2626
             Project: Hibernate3
          Issue Type: Bug
    Affects Versions: 3.2.4.sp1, 3.2.4, 3.2.3
         Environment: Hibernate 3.2.3 - 3.2.4.sp1; Any Database
            Reporter: Michael Plöd
            Priority: Critical
         Attachments: patch.txt, TestCase.zip

I found a bug, that got introduced by adding functionality to the class TypeFactory in Hibernate 3.2.3. The Method TypeFactory#replaceAssociations(...) now has some special handling regarding components / embeddables. But if such a component is null, wich is fair enough, Hibernate will provoke a NullPointerException in sun.reflect.UnsafeFieldAccessorImpl.ensureObj(...):

Exception in thread "main" javax.persistence.PersistenceException: org.hibernate.PropertyAccessException: could not get a field value by reflection getter of de.ploed.test.MonetaryAmount.amount
	at org.hibernate.ejb.AbstractEntityManagerImpl.throwPersistenceException(AbstractEntityManagerImpl.java:647)
	at org.hibernate.ejb.AbstractEntityManagerImpl.merge(AbstractEntityManagerImpl.java:236)
	at de.ploed.test.EntityManagerTest.main(EntityManagerTest.java:22)
Caused by: org.hibernate.PropertyAccessException: could not get a field value by reflection getter of de.ploed.test.MonetaryAmount.amount
	at org.hibernate.property.DirectPropertyAccessor$DirectGetter.get(DirectPropertyAccessor.java:35)
	at org.hibernate.tuple.component.AbstractComponentTuplizer.getPropertyValue(AbstractComponentTuplizer.java:64)
	at org.hibernate.tuple.component.AbstractComponentTuplizer.getPropertyValues(AbstractComponentTuplizer.java:70)
	at org.hibernate.tuple.component.PojoComponentTuplizer.getPropertyValues(PojoComponentTuplizer.java:83)
	at org.hibernate.type.ComponentType.getPropertyValues(ComponentType.java:353)
	at org.hibernate.type.ComponentType.getPropertyValues(ComponentType.java:348)
	at org.hibernate.type.TypeFactory.replaceAssociations(TypeFactory.java:556)
	at org.hibernate.event.def.DefaultMergeEventListener.copyValues(DefaultMergeEventListener.java:366)
	at org.hibernate.event.def.DefaultMergeEventListener.entityIsTransient(DefaultMergeEventListener.java:195)
	at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:123)
	at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:53)
	at org.hibernate.impl.SessionImpl.fireMerge(SessionImpl.java:677)
	at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:661)
	at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:665)
	at org.hibernate.ejb.AbstractEntityManagerImpl.merge(AbstractEntityManagerImpl.java:227)
	... 1 more
Caused by: java.lang.NullPointerException
	at sun.reflect.UnsafeFieldAccessorImpl.ensureObj(UnsafeFieldAccessorImpl.java:36)
	at sun.reflect.UnsafeObjectFieldAccessorImpl.get(UnsafeObjectFieldAccessorImpl.java:18)
	at java.lang.reflect.Field.get(Field.java:357)
	at org.hibernate.property.DirectPropertyAccessor$DirectGetter.get(DirectPropertyAccessor.java:32)
	... 15 more

I think that the handling of target[i] in Line 556 of org.hibernate.type.TypeFactory is not null safe. I have created a patch for this and the bug above appears to be fixed in this patch.

In my humble opinion this bug makes it impossible to merge any entity / value object containing a null reference to another value object.
However this bug is not present when using session.save or session.saveOrUpdate. 

I was able to reproduce the bug in Hibernate Core 3.2.4.sp1, 3.2.4 and 3.2.3 .. It is not present in Hibernate Core Versions <= 3.2.2

Attached to this task are the following files:
patch.txt - my patch proposal
TestCase.zip - Test Case

Please get back to me if you have any further questions!

Cheers,
Mike


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