[rules-users] Getting facts from external source using 'from' and parametrized method call

[Jaroslaw Kijanowski]

And did the stack trace change? Can you post more details (drl, java src)?

Przemysław Różycki wrote:
> Yes, I did. This was the first thing I've checked.
> 
> Best regards,
> Przemek
> 
> Jaroslaw Kijanowski pisze:
>> Did you set the global on your session?
>>
>> http://downloads.jboss.com/drools/docs/4.0.7.19894.GA/html_single/index.html#d0e948 
>>
>>
>> Cheers
>>
>> Przemysław Różycki wrote:
>>> Sorry for responsing myself, but I'm still working on it and found 
>>> that when factSource is a fact, not global, the rule works very well. 
>>> I mean, this rule works fine:
>>>
>>> rule "My Rule"
>>>   when
>>>     $factSrc : FactSource(  )
>>>     $fact : Fact(  ) from $factSrc.getSomeFacts("a","b","c")
>>>   then
>>>     // do something
>>> end
>>>
>>> so what's the difference between invocation on global object and 
>>> invocation on fact object? Why the first one doesn't work and the 
>>> second one works?
>>>
>>> Best regards,
>>> Przemek
>>>
>>>
>>> Przemysław Różycki pisze:
>>>> Hi,
>>>>
>>>> could I ask for some advice, please, how to use a parametrized 
>>>> method call to get some data using 'from' element in LHS.
>>>>
>>>> To be more precise, I would like to do something like this:
>>>>
>>>> rule "My Rule"
>>>>   when
>>>>     $fact : Fact(  ) from factSource.getSomeFacts("a","b","c")
>>>>   then
>>>>     // do something
>>>> end
>>>>
>>>> where factSource is for example some global and 
>>>> getSomeFacts(String,String,String) is a parametrized method that 
>>>> returns some array of Fact objects.
>>>>
>>>> Unfortunately, when I try to launch the following rule I have an error:
>>>>
>>>> Exception in thread "main" org.mvel.PropertyAccessException: unable 
>>>> to resolve property: factSource.getSomeFacts("a","b","c")
>>>>     at 
>>>> org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:295) 
>>>>
>>>>     at 
>>>> org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.optimizeAccessor(ReflectiveAccessorOptimizer.java:110) 
>>>>
>>>>     at 
>>>> org.mvel.ast.VariableDeepPropertyNode.getReducedValueAccelerated(VariableDeepPropertyNode.java:26) 
>>>>
>>>>     at 
>>>> org.mvel.ast.PropertyASTNode.initializePropertyNode(PropertyASTNode.java:70) 
>>>>
>>>>     at 
>>>> org.mvel.ast.PropertyASTNode.getReducedValueAccelerated(PropertyASTNode.java:24) 
>>>>
>>>>     at org.mvel.MVELRuntime.execute(MVELRuntime.java:90)
>>>>     at 
>>>> org.mvel.CompiledExpression.getValue(CompiledExpression.java:111)
>>>>     at org.mvel.MVEL.executeExpression(MVEL.java:252)
>>>>     at 
>>>> org.drools.base.dataproviders.MVELDataProvider.getResults(MVELDataProvider.java:55) 
>>>>
>>>>     at org.drools.reteoo.FromNode.assertTuple(FromNode.java:68)
>>>>     at 
>>>> org.drools.reteoo.SingleTupleSinkAdapter.createAndPropagateAssertTuple(SingleTupleSinkAdapter.java:55) 
>>>>
>>>>     at 
>>>> org.drools.reteoo.LeftInputAdapterNode.assertObject(LeftInputAdapterNode.java:116) 
>>>>
>>>>     at 
>>>> org.drools.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObjectSinkAdapter.java:22) 
>>>>
>>>>     at 
>>>> org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:162)
>>>>     at org.drools.reteoo.Rete.assertObject(Rete.java:175)
>>>>     at 
>>>> org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java:192)
>>>>     at 
>>>> org.drools.reteoo.ReteooWorkingMemory$WorkingMemoryReteAssertAction.execute(ReteooWorkingMemory.java:181) 
>>>>
>>>>     at 
>>>> org.drools.common.AbstractWorkingMemory.executeQueuedActions(AbstractWorkingMemory.java:1312) 
>>>>
>>>>     at 
>>>> org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:915) 
>>>>
>>>>     at 
>>>> org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:883) 
>>>>
>>>>     at 
>>>> org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:684) 
>>>>
>>>>     at com.sample.DroolsTest6.main(DroolsTest6.java:29)
>>>> Caused by: java.lang.NullPointerException
>>>>     at 
>>>> org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.getMethod(ReflectiveAccessorOptimizer.java:530) 
>>>>
>>>>     at 
>>>> org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:261) 
>>>>
>>>>     ... 21 more
>>>>
>>>> Documentation says:
>>>>
>>>> "The from Conditional Element allows users to specify a source for 
>>>> patterns to reason over. This allows the engine to reason over data 
>>>> not in the Working Memory. This could be a sub-field on a bound 
>>>> variable or the results of a method call."
>>>>
>>>> so I assume that it is possible to do what I want. If not, could I 
>>>> ask for an advice of some workaround, please?
>>>>
>>>> Best regards,
>>>
>>> _______________________________________________
>>> rules-users mailing list
>>> rules-users at lists.jboss.org
>>> https://lists.jboss.org/mailman/listinfo/rules-users
>>>
>>
>> _______________________________________________
>> rules-users mailing list
>> rules-users at lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/rules-users
> 
> _______________________________________________
> rules-users mailing list
> rules-users at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>