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

[Edson Tirelli (JIRA)]

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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