Re: [rules-users] How to limit results from a collect statement

Ok, I'm still working on that, I'll publish my solution asap. In the meantime it turns out our requirements need something more than that. We have an ordered list of beans (items) and we have to be able to modify a specific subset of the list (adding a discount). Now I tried to solve this problem by working directly on the list of items. But I can't understand why this doesn't work: when $itemList : ArrayList() from collect( Item( category == "VIDEO" ) ) then ItemDiscount disc = new ItemDiscount(10); $myFirstItem = (Item)$itemList.get(0); $mySecondItem = (Item)$itemList.get(1); $myFirstItem.addDiscount(disc); $mySecondItem.addDiscount(disc); After executing this rule it's like nothing happened! I mean no discount has been added to the two items! The problem seems to be related to extracting items from the list. Apparently, every time we get an item from the list, it looses its link with the original item (I don't know if it's a copy of the original item or whatever), so that every update doesn't affect the original item any more. But of course that's what we're interested in! We want to modify original items in the rule session. Am I missing something? Or Is it a bug? Regards, CG Edson Tirelli-3 wrote: > > Please, share with us! Send to the list! > > Edson > > 2007/8/21, pentarious <cristiano.giuffrida(a)gmail.com&gt;: >> >> >> I found an interesting implementation to do that. If anyone is interested >> I >> could share my solution. >> >> Regards, >> >> CG >> >> >> Mark Proctor wrote: >> > >> > There is no supported way to do this. You could use an inline-eval >> > against a global, but that is very clunkey. However it does seem like a >> > good feature idea for a future release, open a jira and I'll look into >> > getting it included. >> > >> > Mark >> > pentarious wrote: >> >> Does anyone know a method to limit the number of results from a >> collect >> >> statement? I was just wondering how to do something like this: >> >> $myList : List() from collect( MyObject(myField == "something") ) >> limit >> 3 >> >> //it should put in $myList just the first 3 objects retrieved >> >> I'm quite sure there is nothing in Drools which can natively support >> >> something like that. So, how to do that, if needed? I tried this, but >> it >> >> seems not to be working (I can't understand why, though): >> >> $myList : List() from collect( MyObject(myField == "something") ) >> >> $myObject : MyObject() from $myList >> >> eval( $myList.indexOf($myObject) < 3 ) >> >> Indeed, it doesn't work because the link beetween $myList and >> $myObject >> >> seems to be released during any execution of the rule (In fact >> >> $myList.contains($myObject) returns false! Again, I can't understand >> >> why...) >> >> >> >> Any advice would be really appreciated! >> >> >> >> Regards, >> >> >> >> CG >> >> >> > >> > _______________________________________________ >> > rules-users mailing list >> > rules-users(a)lists.jboss.org >> > https://lists.jboss.org/mailman/listinfo/rules-users >> > >> > >> >> -- >> View this message in context: >> http://www.nabble.com/How-to-limit-results-from-a-collect-statement-tf423... >> Sent from the drools - user mailing list archive at Nabble.com. >> >> _______________________________________________ >> rules-users mailing list >> rules-users(a)lists.jboss.org >> https://lists.jboss.org/mailman/listinfo/rules-users >> > > > > -- > Edson Tirelli > Software Engineer - JBoss Rules Core Developer > Office: +55 11 3529-6000 > Mobile: +55 11 9287-5646 > JBoss, a division of Red Hat @ www.jboss.com > > _______________________________________________ > rules-users mailing list > rules-users(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/rules-users > > -- View this message in context: http://www.nabble.com/How-to-limit-results-from-a-collect-statement-tf423... Sent from the drools - user mailing list archive at Nabble.com. _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users