[rules-users] Help on using Drools with embedded objects

[Sudhir M]

Is B name of the class? If so it should be name of the variable not the
class name.As you are using 4.0.7 the above rule can be written as:

rule "test"
       salience 20
       no-loop true
       when
               $a:A( $b : b);
               B(X=="testValue") from $b
            // eval (b.X == "testValue"); using eval is not a good idea.
There might be a performance hit.

       then
               $a.setSomething();
               update($a);
       end

Regards,
sudhir

On Mon, Feb 23, 2009 at 5:59 PM, D1vy@@Ind1@
<divya.rajendranath at gmail.com>wrote:

>
> Sudhir,
> Thanks for the information ...
>
> To give more data..
> I am using drools 4.0.7 version.
>
> I have appropriate setters and getters in all my classes A, B, Z.
>
> My drools file look like this:
>
> rule "test"
>        salience 20
>        no-loop true
>        when
>                $a:A( b : B);
>                eval (b.X == "testValue");
>         then
>                $a.setSomething();
>                update($a);
>        end
>
> When I run this rule, it says
>
> Unable to create Field Extractor for 'B' : [Rule name=test,
> agendaGroup=MAIN, salience=20, no-loop=true]
> org.drools.RuntimeDroolsException: org.drools.RuntimeDroolsException:
> Field/method 'B' not found for class 'com.test.java.A'
> Rule Compilation error : [Rule name=test, agendaGroup=MAIN, salience=20,
> no-loop=true]
>        Rule_test_0.java (8:323) : b.X cannot be resolved to a type
> E
>
> I have double checked if there was any typos in defining my fields, and
> there exists no problem due to typos.
>
> Could you please throw light on this exception ?
>
>
> Thanks
> -D
>
>
>
>
> D1vy@@Ind1@ wrote:
> >
> > Hi,
> >
> > I am planning to use Drools - JBoss Rules Engine. My requirement is to
> > disburse mails from my application to different groups based on various
> > criteria. I want to use Drools here.
> >
> > My object structure is as follows:
> >
> > class A{
> >
> > String B = "";
> >
> > B b;
> >
> > C c;
> > }
> >
> > Hence Obj A has embedded objects within it, and obj B and C further has
> > embedded objects.
> >
> > class B {
> >
> > String X;
> >
> > Z z;
> >
> > }
> >
> > class Z{
> >
> > String t;
> >
> > String s;
> >
> > }
> >
> > The decision on sending the mails based on the fields in embedded objects
> > of
> > A. I pass instance of A to Drools
> >
> > Format of drl file:
> >
> > package...;
> >
> > import ..;
> >
> > rule "Test"
> >
> > when $a:A(B(Z(s == "testvalue")))
> >
> > then
> >
> > $a.setSomething();
> >
> > update($a);
> >
> > end
> >
> > I wanted to know if this (accessing fields in embedded/child object) is
> > feasible with Drools.
> >
> > I get an error saying "UNable to compile myfile.drl when i try to fo
> this.
> >
> > Could some one look into this issue and let me know the reason for this ?
> >
> >
> >
> > Thanks
> >
> > -D
> >
> > _______________________________________________
> > rules-users mailing list
> > rules-users at lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/rules-users
> >
> >
>
> --
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> http://www.nabble.com/Help-on-using-Drools-with-embedded-objects-tp22158087p22160635.html
> Sent from the drools - user mailing list archive at Nabble.com.
>
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