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

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@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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