[rules-users] keep only one, retract all other

[Esteban Aliverti]

Another way to obtain what you are looking for could be this:

rule "Remove all but one"
when
    $f1: Fact(id == "aaa")
    $f2: Fact(id == "aaa", this != $f1)
then
    retract($f2);
end

The difference with this approach is the number of activations you will
have.

Best Regards,


XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Esteban Aliverti
- Blog @ http://ilesteban.wordpress.com


On Fri, Nov 30, 2012 at 10:06 AM, Wolfgang Laun <wolfgang.laun at gmail.com>wrote:

> It seems you are using dialect "mvel"? This doesn't work
> in 5.2.0, 5.3.0 and 5.4.0. (I haven't tried 5.5)
>
> Use dialect java.
>
> -W
>
> On 30/11/2012, Martin Minka <martin.minka at gmail.com> wrote:
> > I was using ArrayList before and I don't think this is the real problem.
> > collect() will return object compatible with List interface so it is
> valid
> > to use size() and get() methods on $removeUs.
> > I have helper method myhelper.log() with accepts any object and *
> > myhelper.log($removeUs.get(i))* works for me, unfortunately
> > *retract($removeUs.get(i))
> > *doesn't work with error:
> >
> > Error: unable to resolve method using strict-mode:
> > org.drools.spi.KnowledgeHelper.drools()] [Near : {...
> > drools.retract($removeUs ....}]
> >
> > It looks like it is not even compiled.
> >
> > 2012/11/30 Wolfgang Laun <wolfgang.laun at gmail.com>
> >
> >> On 30/11/2012, Martin Minka <martin.minka at gmail.com> wrote:
> >> > Thank you for the tip. What solution would you suggest to solve my
> >> problem
> >> > ?
> >>
> >> Look into the javadoc of java.util to find any class implementing List
> >> :-)
> >> -W
> >>
> >> >
> >> > Martin
> >> >
> >> >
> >> > 2012/11/30 Wolfgang Laun <wolfgang.laun at gmail.com>
> >> >
> >> >> You cannot use an interfact (List) to instantiate an object, which
> >> >> is happening due to the collect.
> >> >> --W
> >> >>
> >> >> On 30/11/2012, Martin Minka <martin.minka at gmail.com> wrote:
> >> >> > I want to keep only 1 fact with id=="aaaa". But this is not
> working:
> >> >> >
> >> >> > rule "leave only one"
> >> >> > when
> >> >> >     $removeUs : java.util.List(size>1)
> >> >> >         from collect(Fact(id=="aaaa")
> >> >> > then
> >> >> >     size = $removeUs.size();
> >> >> >     for (int i=1; i < size; i++) {
> >> >> >         retract($removeUs.get(i));
> >> >> >     }
> >> >> > end
> >> >> >
> >> >> _______________________________________________
> >> >> rules-users mailing list
> >> >> rules-users at lists.jboss.org
> >> >> https://lists.jboss.org/mailman/listinfo/rules-users
> >> >>
> >> >
> >> _______________________________________________
> >> rules-users mailing list
> >> rules-users at lists.jboss.org
> >> https://lists.jboss.org/mailman/listinfo/rules-users
> >>
> >
> _______________________________________________
> rules-users mailing list
> rules-users at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>
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