[rules-users] RE: Help with syntax for detecting when an object exists, none of whose children match a pattern

[Vikrant Yagnick]

I am a bit of a newbie myself, but I assume the following would work:

When
 $p: ParentFactObject()
$c: childFactObject(TestMe==false) from $p.ChildFactObjectList
Then
//do something
End

Another way is to simply assert the ChildFactObjectList as separate facts into the working memory and then pattern match just them.

Cheers,
Vikrant


From: rules-users-bounces at lists.jboss.org [mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Tom.E.Murphy at wellsfargo.com
Sent: Saturday, September 06, 2008 2:49 AM
To: rules-users at lists.jboss.org
Subject: [rules-users] Help with syntax for detecting when an object exists, none of whose children match a pattern


As a newbie to Drools (using v4.0.7), I'm struggling a bit with the right way to express the following concept

I have a ParentFactObject with an array of ChildFactObjects.

The ChildFactObjects have a boolean attribute "TestMe"

I want to pattern match all ParentFactObjects for whom all ChildFactObjects have false for TestMe

Here's what I've tried:

rule "NoTestChildren"

        when

                $parentFactObject : ParentFactObject // parent exists

                (

                )

                not ChildFactObject     // no child exists that has TestMe true

                (

                        TestMe == true

                ) from $parentFactObject.childFactObjects

        then

                log("Rule NoTestChildren fired.");

end

I get the following:

org.drools.rule.InvalidRulePackage: [66,4]: unknown:66:4 mismatched token: [@1085,4469:4472='from',<38>,66:4]; expecting type THEN

Also tried this:

rule " NoTestChildren "

        when

                $parentFactObject : Borrower // parent exists

                (

                )

                forall ($childFactObject : ChildFactObject      // no child exists that has TestMe true

                (

                        TestMe == true

                ) )from $parentFactObject. childFactObjects

        then

                log("Rule NoTestChildren fired.");

end

I've tried a series of variations with similar results.

Can anyone provide any guidance on how to do this?

Thanks in advance.

Tom Murphy

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