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

[Przemysław Różycki]

Hi,

I mean, I checked the global and it was set.

I'm attaching the code, that causes the problem (Java and DRL). You need 
just to set a proper path to DRL file while setting file property in 
Java file. I think, the global is set in proper way.
In DRL, depending which rule is commented/uncommented, the code works or 
not.

Best regards,
Przemek

Jaroslaw Kijanowski pisze:
> 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,
>>>>
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>>>>
>>>
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>>
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> 
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