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My drl is:

rule "Active Orders"
    dialect "mvel"
    //no-loop
    when
        m: Order( status == Order.ENABLED, id : id )
    then
        System.out.println( "Order Id is: " + id );
        modify ( m ) 
        { 
            status = Order.DISABLED  
        };
end

I pass a single Order instance to the drools like this: 

Order order = new Order();
order.setId(100);
order.setStatus( Order.ENABLED );
ksession.insert( order );

ksession.fireAllRules();

I am seeing that the rules are fired infinitely with message:

Order Id is: 100
Order Id is: 100
Order Id is: 100
.....

I can understand the infinite-loop, but the key thing is i am setting Order Status to DISABLED in modify block:
status = Order.DISABLED

Therefore, the when rule is fired again....The WHEN condition i.e status == Order.ENABLED , should not be satisfied, and i should not see the system.out.println message more than once.

Any idea, what am i doing wrong?
(Pls note: My problem is not Infinite loop, but why rule is evaluated incorrectly after object modification)

Jasper
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1 Answers1

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The syntax in your modify block is wrong (actually I'm not sure why it even compiles and what it is doing). Try this:

modify(m){
    setStatus(Order.ENABLED);
}

Hope it helps,

Esteban Aliverti
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  • Tried that but - this causes: Exception in thread "main" Exception executing consequence for rule "Active Orders" in [Error: unable to resolve method: org.drools.base.DefaultKnowledgeHelper.setStatus(java.lang.Integer) [arglength=1]] - Its looking for setStatus method against DefaultKnowledgeHelper object! – Jasper Aug 11 '13 at 04:55