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

Well, it must work. Can you open a JIRA with a self contained test case please? I will investigate. []s Edson 2007/8/22, pentarious <cristiano.giuffrida(a)gmail.com&gt;: > > > I know. Actually I didn't put any update or insert statement in the code > just > to make it simpler. The actual code looks like: > when > $itemList : ArrayList() from collect( Item( category == "VIDEO" ) ) > then > ItemDiscount disc = new ItemDiscount(10); > insert(disc); > $myFirstItem = (Item)$itemList.get(0); > $mySecondItem = (Item)$itemList.get(1); > $myFirstItem.addDiscount(disc); > $mySecondItem.addDiscount(disc); > update($myFirstItem); > update($mySecondItem); > Now, why this doesn't work at all? It does work if I write a rule for > each > item using in the when clause $item : Item from $itemList, but as I said > I > need to write a list-oriented rule. > > Regards, > > CG > > > Edson Tirelli-3 wrote: > > > > If you want the "engine to see" your changes, in a way you affect > other > > rules, you must call update( object ) for the object you are changing. > > Otherwise, the change will happen to the original object, but not to > the > > shadow proxy that the engine uses to ensure consistency. > > > > []s > > Edson > > > > 2007/8/22, pentarious <cristiano.giuffrida(a)gmail.com&gt;: > >> > >> > >> 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 > >> > > > > > > > > -- > > 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 > -- 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