[rules-users] mvel error?

Edson Tirelli tirelli at post.com
Fri Apr 25 08:50:59 EDT 2008 

   I don't know what sum( $person ) means, :) but nested accessors
definitively should work:

Number () from accumulate (
$person : Person(
age > 18,
dog.weight > 50
),
sum($person)
)

    In Cristine's case, a NPE is being raised:

Caused by: java.lang.NullPointerException

   Did you guys tried 4.0.7, that is about to be released? Does the error
still happens there?

   []s
   Edson



2008/4/25 Chris Woodrow <woodrow.chris at gmail.com>:

> Hi,
> I found out I had this king of errors when I was using nested accessors
> like :
>
> Number () from accumulate (
> $person : Person(
> age > 18,
> dog.weight > 50
> ),
> sum($person)
> )
>
> I found I could get rid of these this way :
>
> Number () from accumulate (
> $person : Person(
> age > 18
> )&& eval($person.getDog().getWeight()>50),
> sum($person)
>  )
>
> I guess it is not optimized at all, but at least it does not raise strange
> exception.
> Chris
>
>
>
> 2008/4/25 Christine <christine at christine.nl>:
>
> Hi,
>> does anyone know what this error means?
>> It happens when I put an enum constant in a rule. I use the same enum
>> constant in another part of the same rule with no problem.
>>
>> Christine
>>
>> org.drools.RuntimeDroolsException: Exception executing predicate
>> org.drools.base.mvel.MVELPredicateExpression at 125844f
>>        at
>>
>> org.drools.rule.PredicateConstraint.isAllowed(PredicateConstraint.java:216)
>>        at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:132)
>>        at
>>
>> org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:318)
>>        at
>> org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:153)
>>        at org.drools.reteoo.Rete.assertObject(Rete.java:175)
>>        at
>> org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java:192)
>>        at
>>
>> org.drools.reteoo.ReteooWorkingMemory.doInsert(ReteooWorkingMemory.java:71)
>>        at
>>
>> org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:909)
>>        at
>>
>> org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:881)
>>        at
>>
>> org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:682)
>>        at
>>
>> nl.ing.towardsdeepdrive.rules.SalesRules.assertCompetitorProduct(SalesRules.java:42)
>>        at rules.SalesRulesTest.TestRules(SalesRulesTest.java:53)
>>        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>>        at
>>
>> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
>>        at
>>
>> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
>>        at java.lang.reflect.Method.invoke(Method.java:585)
>>        at org.junit.internal.runners.TestMethod.invoke(TestMethod.java:59)
>>        at
>>
>> org.junit.internal.runners.MethodRoadie.runTestMethod(MethodRoadie.java:98)
>>        at
>> org.junit.internal.runners.MethodRoadie$2.run(MethodRoadie.java:79)
>>        at
>>
>> org.junit.internal.runners.MethodRoadie.runBeforesThenTestThenAfters(MethodRoadie.java:87)
>>        at
>> org.junit.internal.runners.MethodRoadie.runTest(MethodRoadie.java:77)
>>        at
>> org.junit.internal.runners.MethodRoadie.run(MethodRoadie.java:42)
>>        at
>>
>> org.junit.internal.runners.JUnit4ClassRunner.invokeTestMethod(JUnit4ClassRunner.java:88)
>>        at
>>
>> org.junit.internal.runners.JUnit4ClassRunner.runMethods(JUnit4ClassRunner.java:51)
>>        at
>>
>> org.junit.internal.runners.JUnit4ClassRunner$1.run(JUnit4ClassRunner.java:44)
>>        at
>> org.junit.internal.runners.ClassRoadie.runUnprotected(ClassRoadie.java:27)
>>        at
>> org.junit.internal.runners.ClassRoadie.runProtected(ClassRoadie.java:37)
>>        at
>>
>> org.junit.internal.runners.JUnit4ClassRunner.run(JUnit4ClassRunner.java:42)
>>        at
>>
>> org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:38)
>>        at
>>
>> org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
>>        at
>>
>> org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:460)
>>        at
>>
>> org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673)
>>        at
>>
>> org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386)
>>        at
>>
>> org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196)
>> Caused by: org.mvel.CompileException: cannot invoke getter: getType
>> [declr.class: nl.ing.towardsdeepdrive.data.model.Product; act.class: null]
>>        at
>>
>> org.mvel.optimizers.impl.refl.GetterAccessor.getValue(GetterAccessor.java:52)
>>        at
>>
>> org.mvel.optimizers.impl.refl.VariableAccessor.getValue(VariableAccessor.java:39)
>>        at
>>
>> org.mvel.ast.VariableDeepPropertyNode.getReducedValueAccelerated(VariableDeepPropertyNode.java:22)
>>        at
>>
>> org.mvel.ast.PropertyASTNode.getReducedValueAccelerated(PropertyASTNode.java:21)
>>        at
>>
>> org.mvel.ast.BinaryOperation.getReducedValueAccelerated(BinaryOperation.java:21)
>>        at org.mvel.MVELRuntime.execute(MVELRuntime.java:88)
>>        at
>> org.mvel.CompiledExpression.getValue(CompiledExpression.java:111)
>>        at org.mvel.MVEL.executeExpression(MVEL.java:235)
>>        at
>>
>> org.drools.base.mvel.MVELPredicateExpression.evaluate(MVELPredicateExpression.java:36)
>>        at
>>
>> org.drools.rule.PredicateConstraint.isAllowed(PredicateConstraint.java:210)
>>        ... 33 more
>> Caused by: java.lang.NullPointerException
>>        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>>        at
>>
>> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
>>        at
>>
>> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
>>        at java.lang.reflect.Method.invoke(Method.java:585)
>>        at
>>
>> org.mvel.optimizers.impl.refl.GetterAccessor.getValue(GetterAccessor.java:42)
>>        ... 42 more
>>
>>
>>
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>
>
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-- 
Edson Tirelli
JBoss Drools Core Development
Office: +55 11 3529-6000
Mobile: +55 11 9287-5646
JBoss, a division of Red Hat @ www.jboss.com
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