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
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