[rules-users] rule on Array of custom Object

[Swindells, Thomas]

Have you tried making your classes beans?
Eg adding getters and setters. (As a style guide in java you should generally avoid public fields and class names should start with a capital letter).

This would give you the following:
public class Message {
    private Numbers[] numbersArray;


    protected Numbers[] getNumbersArray() {
        return numbersArray;
    }

    protected void setNumbersArray(Numbers[] numbersArray) {
        this.numbersArray = numbersArray;
    }
}

public class Numbers {
    private int first;
    private int last;

    protected int getFirst() {
        return first;
    }

    protected void setFirst(int first) {
        this.first = first;
    }

    protected int getLast() {
        return last;
    }

    protected void setLast(int last) {
        this.last = last;
    }
}

Thomas

From: rules-users-bounces at lists.jboss.org [mailto:rules-users-bounces at lists.jboss.org] On Behalf Of stefano corna
Sent: 14 December 2009 11:00
To: rules-users at lists.jboss.org
Subject: [rules-users] rule on Array of custom Object

hello,
im using drools 5.0 on eclipse and i have a problem. i want to use an array of object in my rule condition.
now i try to explain:
i have my java class with the array attribute
-------------------------------------------------
public static class Message {

   public numbers[] numbersArray;

}
--------------------------------------------
and the numbers class that rapresent the objects contained in numbersArray
----------------------------------------------
public static class numbers
{
   public int first;
   public int last;
}
--------------------------------------------------
my goal is make a rule that check if Message.numbersArray[0].first="value"
i use
-------------------------------------------------
rule "rule_001"

dialect "mvel"
when
        $msg : Message(numbersArray[0].first=="1")

then
                System.out.println("something....");
end
-------------------------------
and on runtime it give me this error:
---------------------------------------
org.drools.RuntimeDroolsException: Exception executing predicate numbersArray[0].first=="1"
        at org.drools.rule.PredicateConstraint.isAllowed(PredicateConstraint.java:279)
        at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:143)
        at org.drools.reteoo.CompositeObjectSinkAdapter.doPropagateAssertObject(CompositeObjectSinkAdapter.java:360)
        at org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:344)
        at org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:185)
        at org.drools.reteoo.EntryPointNode.assertObject(EntryPointNode.java:146)
        at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:1046)
        at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:1001)
        at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:788)
        at org.drools.impl.StatefulKnowledgeSessionImpl.insert(StatefulKnowledgeSessionImpl.java:216)
        at com.sample.DroolsTest.main(DroolsTest.java:47)
Caused by: [Error: unable to access property (null parent): first]
[Near : {... Unknown ....}]
             ^
[Line: 1, Column: 0]
        at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.getMethod(ReflectiveAccessorOptimizer.java:861)
        at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.getBeanProperty(ReflectiveAccessorOptimizer.java:585)
        at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:313)
        at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.optimizeAccessor(ReflectiveAccessorOptimizer.java:138)
        at org.mvel2.ast.ASTNode.getReducedValueAccelerated(ASTNode.java:133)
        at org.mvel2.ast.BinaryOperation.getReducedValueAccelerated(BinaryOperation.java:102)
        at org.mvel2.MVELRuntime.execute(MVELRuntime.java:85)
        at org.mvel2.compiler.CompiledExpression.getValue(CompiledExpression.java:107)
        at org.mvel2.MVEL.executeExpression(MVEL.java:978)
        at org.drools.base.mvel.MVELPredicateExpression.evaluate(MVELPredicateExpression.java:75)
        at org.drools.rule.PredicateConstraint.isAllowed(PredicateConstraint.java:272)
        ... 10 more
-------------------------------------------------------
moreover if i try to print the "first" value:
.
.
.
then
                System.out.println(numbersArray[0].first);
end
appear this new error and i cant compile:
"BuildError: Unable to build expression for 'consequence': Failed to compile: 1 compilation error(s):
 - (1,12) unqualified type in strict mode for: numbersArray' System.out.println(numbersArray[0].first);
'"

someone can kindly help me?

________________________________

**************************************************************************************
This message is confidential and intended only for the addressee. If you have received this message in error, please immediately notify the postmaster at nds.com and delete it from your system as well as any copies. The content of e-mails as well as traffic data may be monitored by NDS for employment and security purposes. To protect the environment please do not print this e-mail unless necessary.

NDS Limited. Registered Office: One London Road, Staines, Middlesex, TW18 4EX, United Kingdom. A company registered in England and Wales. Registered no. 3080780. VAT no. GB 603 8808 40-00
**************************************************************************************

________________________________
This message is confidential and intended only for the addressee. If you have received this message in error, please immediately notify the postmaster at nds.com and delete it from your system as well as any copies. The content of e-mails as well as traffic data may be monitored by NDS for employment and security purposes.
To protect the environment please do not print this e-mail unless necessary.

An NDS Group Limited company. www.nds.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.jboss.org/pipermail/rules-users/attachments/20091214/4505954d/attachment.html