In this rule, $facts is bound to a "live" ArrayList, i.e., a retract has an immediate effect on the collection. Iterate a copy for retracting all in a single firing.
That said, it might be better to write a simple rule retracting each matching Fact individually. Collecting the list and retracting from a copy does not avoid updating the agenda with this rule, 9 times for 10 matching Fact facts. -W On 25/05/2013, Weiss, Wolfgang <wolfgang.we...@joanneum.at> wrote: > Hi, > > I want to delete a list of facts from the working memory and therefore > created following rule: > > rule "delete rule" > agenda-group "evaluation" > salience 50 > no-loop true > > when > $facts : ArrayList(size > 0) from collect (Fact()) > then > logger.info("delete rule, number of facts in list: " + $facts.size()); > > for (int i = 0; i < $facts.size(); i++) { > Fact f = (Fact)$facts.get(i); > logger.info("retract fact id: " + f.getId()); > retract(f); > } > end > > When inserting 10 facts with IDs 1 to 10 and then fire all rules, I get > following result: > delete rule, number of facts in list: 10 > retract fact id: 1 > retract fact id: 3 > retract fact id: 5 > retract fact id: 7 > retract fact id: 9 > > but, the facts 2, 4, 6, 8 and 10 are not deleted. I would have expected to > set "no-loop" to true, as I do some modification of facts and don't want > that this rule is fired again with the same facts. When I set "no-loop" to > false, I get following result: > delete rule, number of facts in list: 10 > retract fact id: 1 > retract fact id: 3 > retract fact id: 5 > retract fact id: 7 > retract fact id: 9 > delete rule, number of facts in list: 5 > retract fact id: 2 > retract fact id: 6 > retract fact id: 10 > delete rule, number of facts in list: 2 > retract fact id: 4 > delete rule, number of facts in list: 1 > retract fact id: 8 > > now, all facts are deleted but the "delete rule" was fired 4 times. Is this > the intended behavior of Drools? Is there a way to fire a rule only once and > delete a list of facts? > I can reproduce this behavior with Drools 5.5.0.Final and 6.0.0.Beta2 but > did not try any other version. > > Best Regards, > Wolfgang > > _______________________________________________ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users