[jboss-jira] [JBoss JIRA] (DROOLS-687) Helpful error message for MvelConstraint

[Geoffrey De Smet (JIRA)]

     [ https://issues.jboss.org/browse/DROOLS-687?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Geoffrey De Smet updated DROOLS-687:
------------------------------------
    Priority: Critical  (was: Major)


> Helpful error message for MvelConstraint
> ----------------------------------------
>
>                 Key: DROOLS-687
>                 URL: https://issues.jboss.org/browse/DROOLS-687
>             Project: Drools
>          Issue Type: Enhancement
>    Affects Versions: 6.2.0.CR4
>            Reporter: Toshiya Kobayashi
>            Assignee: Mario Fusco
>            Priority: Critical
>
> When you hit NullPointerException with LHS constraint during runtime, the error message is not very helpful for users to detect the root cause.
> For example,
> {noformat}
> rule 'hello person'
>    when
>        Person( address.street == 'abbey' )
>    then
> end
> {noformat}
> If Person.address is null, the error message is:
> {noformat}
> [Error: null pointer: address.street]
> [Near : {... address.street == "abbey" ....}]
>              ^
> [Line: 1, Column: 1]
> 	at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:427)
> 	at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.optimizeAccessor(ReflectiveAccessorOptimizer.java:140)
> 	at org.mvel2.ast.ASTNode.optimize(ASTNode.java:159)
> 	at org.mvel2.ast.ASTNode.getReducedValueAccelerated(ASTNode.java:115)
> 	at org.mvel2.ast.BinaryOperation.getReducedValueAccelerated(BinaryOperation.java:117)
> 	at org.mvel2.MVELRuntime.execute(MVELRuntime.java:86)
> 	at org.mvel2.compiler.CompiledExpression.getDirectValue(CompiledExpression.java:123)
> 	at org.mvel2.compiler.CompiledExpression.getValue(CompiledExpression.java:119)
> 	at org.mvel2.compiler.CompiledExpression.getValue(CompiledExpression.java:113)
> 	at org.mvel2.MVEL.executeExpression(MVEL.java:930)
> 	at org.drools.core.util.MVELSafeHelper$RawMVELEvaluator.executeExpression(MVELSafeHelper.java:481)
> 	at org.drools.core.rule.constraint.MvelConditionEvaluator.evaluate(MvelConditionEvaluator.java:77)
> 	at org.drools.core.rule.constraint.MvelConditionEvaluator.evaluate(MvelConditionEvaluator.java:62)
> 	at org.drools.core.rule.constraint.MvelConstraint.evaluate(MvelConstraint.java:226)
> 	at org.drools.core.rule.constraint.MvelConstraint.isAllowed(MvelConstraint.java:183)
> 	at org.drools.core.reteoo.AlphaNode.assertObject(AlphaNode.java:138)
> 	at org.drools.core.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObjectSinkAdapter.java:60)
> 	at org.drools.core.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:290)
> 	at org.drools.core.reteoo.EntryPointNode.assertObject(EntryPointNode.java:253)
> 	at org.drools.core.common.NamedEntryPoint.insert(NamedEntryPoint.java:281)
> 	at org.drools.core.common.NamedEntryPoint.insert(NamedEntryPoint.java:241)
> 	at org.drools.core.impl.StatefulKnowledgeSessionImpl.insert(StatefulKnowledgeSessionImpl.java:1481)
> 	at org.drools.core.impl.StatefulKnowledgeSessionImpl.insert(StatefulKnowledgeSessionImpl.java:1436)
> 	at org.drools.compiler.integrationtests.Misc2Test.testMvelConstraintErrorMessage(Misc2Test.java:7086)
> ...
> Caused by: java.lang.NullPointerException
> 	at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:393)
> 	... 46 more
> {noformat}
> Users cannot identify which rule is associated with the constraint when they have many similar rules. Also users cannot identify which fact (Person) caused the issue when they insert many facts.
> I'm not sure if it's really possible to provide a better message in this case. But I filed this as an enhancement request.



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