[rules-users] Re: how to use Array type in Drools

[Zeke]

Anyone can help me? I want to use an element of an Array in my rule
condition.

Thank you very much!

- Zeke

2009/4/28 Zeke <xanadu860122 at gmail.com>

> Hi,
>   I am using Drools 4.0.7 GA. I want to use Array type in my rule
> condition. My drl is like below:
>
>>   package org.drools.examples.test;
>>
>>   import org.drools.examples.HelloWorldExample.Message;
>>
>>   rule "check.array"
>>       dialect "java"
>>       when
>>           m:Message( arr[0] == "1" )
>>       then
>>           System.out.println( "===check array ok===" );
>>   end
>
>
>   arr is an int type array. When I run the test case, I meet below
> exception:
>
>> Exception in thread "main" org.drools.RuntimeDroolsException: Exception
>> executing predicate eval( arr[0] == "1" )
>>     at
>> org.drools.rule.PredicateConstraint.isAllowed(PredicateConstraint.java:216)
>>     at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:137)
>>     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.doInsert(ReteooWorkingMemory.java:71)
>>     at
>> org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:911)
>>     at
>> org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:883)
>>     at
>> org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:684)
>>     at
>> org.drools.examples.HelloWorldExample.main(HelloWorldExample.java:69)
>> Caused by: org.mvel.CompileException: illegal use of []: unknown type: [I
>>     at
>> org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.getCollectionProperty(ReflectiveAccessorOptimizer.java:482)
>>     at
>> org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:274)
>>     at
>> org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.optimizeAccessor(ReflectiveAccessorOptimizer.java:110)
>>     at org.mvel.ASTNode.getReducedValueAccelerated(ASTNode.java:186)
>>     at
>> org.mvel.ast.BinaryOperation.getReducedValueAccelerated(BinaryOperation.java:21)
>>     at org.mvel.MVELRuntime.execute(MVELRuntime.java:90)
>>     at org.mvel.CompiledExpression.getValue(CompiledExpression.java:111)
>>     at org.mvel.MVEL.executeExpression(MVEL.java:234)
>>     at
>> org.drools.base.mvel.MVELPredicateExpression.evaluate(MVELPredicateExpression.java:45)
>>     at
>> org.drools.rule.PredicateConstraint.isAllowed(PredicateConstraint.java:209)
>>     ... 10 more
>>
>
> Can anyone kindly tell me how to use Array type in Drools? Thanks in
> advance!
>
> - Zeke
>
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