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!

 

 

Thomas