[jboss-jira] [JBoss JIRA] Resolved: (JBRULES-3224) ClassCastException when comparing class type attributes to null

[Edson Tirelli (JIRA)]

     [ https://issues.jboss.org/browse/JBRULES-3224?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Edson Tirelli resolved JBRULES-3224.
------------------------------------

    Resolution: Done


Fixed. Thanks for the bug report and solution analysis.

> ClassCastException when comparing class type attributes to null
> ---------------------------------------------------------------
>
>                 Key: JBRULES-3224
>                 URL: https://issues.jboss.org/browse/JBRULES-3224
>             Project: Drools
>          Issue Type: Bug
>      Security Level: Public(Everyone can see) 
>          Components: drools-core
>    Affects Versions: 5.3.0.CR1
>            Reporter: Edson Tirelli
>            Assignee: Edson Tirelli
>             Fix For: 5.3.0.Final, 5.4.0.Beta1
>
>
> Reported by Thomas:
> ============================
> I've just tried upgrading from Drools 5.3.0-CR1 from the beta and I've hit a regression.
>  
> JBoss seems to have been down for most of today so I haven't been able to raise a Jira for it.
>  
> In our model we have Facts which contain fields of java.lang.class, we then have a rule which checks that they aren't null.
> Eg
> Fact { Class<Object> classField}
>  
> Rule "xyz"
> When
>                 Fact(classField != null)
> Then
> ...
> End
>  
> This is giving the following exception
>  
> Caused by: java.lang.ClassCastException: org.drools.base.field.ObjectFieldImpl cannot be cast to org.drools.base.field.ClassFieldImpl
>                 at org.drools.base.evaluators.EqualityEvaluatorsDefinition$ClassEqualEvaluator.evaluate(EqualityEvaluatorsDefinition.java:1772)
>                 at org.drools.rule.LiteralRestriction.isAllowed(LiteralRestriction.java:87)
>                 at org.drools.rule.LiteralConstraint.isAllowed(LiteralConstraint.java:109)
>                 at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:130)
>                 at org.drools.reteoo.CompositeObjectSinkAdapter.doPropagateAssertObject(CompositeObjectSinkAdapter.java:451)
>                 at org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:369)
>                 at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:134)
>                 at org.drools.reteoo.CompositeObjectSinkAdapter.doPropagateAssertObject(CompositeObjectSinkAdapter.java:451)
>                 at org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:379)
>                 at org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:204)
>                 at org.drools.reteoo.EntryPointNode.assertObject(EntryPointNode.java:244)
>                 at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:330)
>                 at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:291)
>                 at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:882)
>                 at org.drools.base.DefaultKnowledgeHelper.insert(DefaultKnowledgeHelper.java:180)
>                 ... 149 more
>  
> Wrapping the classField != null within an eval appears to be a work around.
>  
> This is in the suspect method:
>         public boolean evaluate(InternalWorkingMemory workingMemory,
>                                 final InternalReadAccessor extractor,
>                                 final Object object1, final FieldValue object2) {
>             Object value1 = extractor.getValue( workingMemory, object1 );
>             Object value2 = object2.getValue();
>             if ( value2 == null ) {
>                 ClassFieldImpl classField = (ClassFieldImpl) object2;
>                 value2 = classField.resolve( workingMemory );
>             }
>             return comparator.equals( value1, value2 );
>         }
>  
> I think the if statement just needs an instanceof check as well or some other way to track the fact that null may be a valid value to be comparing with!
>  

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