Thanks Thomas. I will give your suggestions a try.

Based on my current code, is there a reason why Rule 2 doesn’t fire? I’m assuming Rule 1 should only fire once with “lock-on-active true” set correct? There should be at least one A left after Rule 1 is done (i.e. A with property = 345).

Justin

From: rules-users-bounces@lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Swindells, Thomas
Sent: Wednesday, July 21, 2010 8:51 AM
To: Rules Users List
Subject: Re: [rules-users] Rules not firing when expected after retracting object in list

No the rule is run multiple times, once per a matching A.

If you did only want the rule to run once regardless of how many matching As you have then you would use exists:

Exists A( property == "123" )

From: rules-users-bounces@lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Justin Beltran
Sent: 21 July 2010 16:47
To: 'Rules Users List'
Subject: Re: [rules-users] Rules not firing when expected after retracting object in list

Thanks for the reply.

What if you have multiple A’s set with 123? Don’t you need to collect them to retract all A’s that match that property?

My main concern is if you retract one or more of the A’s, it’s possible that you should still have some A’s that are NOT retracted, so rule B should still fire right?

Justin

From: rules-users-bounces@lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Swindells, Thomas
Sent: Wednesday, July 21, 2010 8:39 AM
To: Rules Users List
Subject: Re: [rules-users] Rules not firing when expected after retracting object in list

Why is rule 1 written the way it is? Why can’t you just do:

rule "Rule 1 - Remove all A's that have property set to 123"
salience 1000
when
$anA : A( property == "123" )
then
retract ($anA)
end

Thomas

From: rules-users-bounces@lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Justin Beltran
Sent: 21 July 2010 16:28
To: rules-users@lists.jboss.org
Subject: [rules-users] Rules not firing when expected after retracting object in list

Hi,

I'm coming across some weird behavior in Drools 4.0.7, but maybe it's just cause I don't understand I how Drools works. Assume, there's a class "A" that has a property called "property".

As facts, I have the following list of A's:
A1, property = 123
A2, property = 345
A3, property = 123

I have two rules as follows:

rule "Rule 1 - Remove all A's that have property set to 123"
salience 1000
lock-on-active true
when
$listOfAs : ArrayList collect(A( property == "123" ))
then
for (Object a: $listOfAs ) {
retract (a)
}
end

rule "Rule 2 - Do stuff with remaining A's"
salience 900
lock-on-active true
when
$listOfAs : ArrayList collect(A())
then
...
end

My understanding is "Rule 1" will remove the facts of class A that have property to 123. When it gets to "Rule 2", shouldn't the "listOfAs" only have that one A that remains (i.e. the one where property is set to "345"). What I'm noticing is that "Rule 2" just doesn't execute at all even though I'm assuming there is still one "A" object that hasn't been retracted. If I comment out the "retract" it executes "Rule 2" fine.

Am I missing something about these rules work?

Thanks.
Justin

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