[rules-users] NullPointer after inserting fact in RHS

[dabar]

I've been battling with drools and just wanting a second viewpoint.  I'm
using drools 5.2.0 flow and rules.
 
I have a rule that inserts a new fact as part of the RHS of the rule and
then I'm getting a null pointer exception - stack below. I assume when the
fact is inserted all the rules are evaluated to build up the agenda.  

I've debugged through drools code and found that in ClassFieldReader object1
is null and object2 is my new fact.
 
I'm interested in what a JoinNode represents as I think this is what is
being evaluated. I would guess its a join node in the flow but these don't
contain any rules so perhaps not.

Similar threads here suggest this is a fault in one of the rules but I have
about 100 rules so working out the culprit isn't straightforward.
What I really want to know is if there a way I can find out which rule is
being assessed for the agenda so I check that rule.

 
Caused by: java.lang.NullPointerException
        at
org.drools.base.com.somecompany.prov.rulesbased.facts.ProvResponse1649170666$getMmlCommandUid.getIntValue(Unknown
Source)
        at
org.drools.base.ClassFieldReader.getIntValue(ClassFieldReader.java:165)
        at
org.drools.base.evaluators.EqualityEvaluatorsDefinition$IntegerEqualEvaluator.evaluate(EqualityEvaluatorsDefinition.java:1522)
        at
org.drools.core.util.AbstractHashTable$SingleIndex.equal(AbstractHashTable.java:619)
        at
org.drools.core.util.LeftTupleList.matches(LeftTupleList.java:190)
        at
org.drools.core.util.LeftTupleIndexHashTable.getOrCreate(LeftTupleIndexHashTable.java:347)
        at
org.drools.core.util.LeftTupleIndexHashTable.add(LeftTupleIndexHashTable.java:233)
        at org.drools.reteoo.JoinNode.assertLeftTuple(JoinNode.java:65)
        at
org.drools.reteoo.SingleLeftTupleSinkAdapter.doPropagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:189)
        at
org.drools.reteoo.SingleLeftTupleSinkAdapter.createAndPropagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:138)
        at
org.drools.reteoo.LeftInputAdapterNode.assertObject(LeftInputAdapterNode.java:148)
        at
org.drools.reteoo.CompositeObjectSinkAdapter.doPropagateAssertObject(CompositeObjectSinkAdapter.java:450)
        at
org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:378)
        at
org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:190)
        at
org.drools.reteoo.EntryPointNode.assertObject(EntryPointNode.java:145)
        at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:1183)
        at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:1085)
        at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:889)
        at
org.drools.impl.StatefulKnowledgeSessionImpl.insert(StatefulKnowledgeSessionImpl.java:238)
        at
com.somecompany.rules.global.RulesUtils.insertFact(RulesUtils.java:159)
        at
com.somecompany.rules.common.Rule_Common_HandleUnexpectedResponse___Mark_an_unexpected_response_as_handled_0.defaultConsequence(Rule_Common_HandleUnexpectedResponse___Mark_an_unexpected_response_as_handled_0.java:28)


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