Hi Brody, I have had similar situation several times, and each time I had to modify my objects to avoid this, and it was really tedious. I'd also would like to know whether it is possible to have a "real solution" in this case without needing to change the base objects, but rather use the rule language to formulate this kind of business rule *why didn't I receive this mail through the mailing list? maybe you haven't subscribed yet?* Brody bach wrote: > > Hi all, > > I have an object which I use as main fact object, let's say "Schedule", > which has a list of objects called "TimeEntry"  ---> > > class Schedule(){ >      List<TimeEntry> entries; > } > > class TimeEntry(){ >      String type; >      Date start; >      Date end; >      Integer length; > } > > > Now, if I insert Schedule into the WM, and would like to iterate over the > list of TimeEntry, due to the following business rule : > > For all time entries, if it is of type BREAK: > check whether a time entry of type WORK exist, > before and/or after this BREAK, which has only length of 10 minutes > > The content of the time entry list has been sorted before so they are all > in correct time order, e.g > > 09:00 - 09:10  WORK (10 min) > 09:10 - 09:30  BREAK (20 min) > 09:30 - 10:30  WORK  (60 min) > --> in this case, the rule should fire > > How can I define this rule? Some questions which I have: > - how do I check previous and next element of the current element? > - the length of the list isn't fix; it may contain 1, 2, or more entries. > So somehow in an attempt to access next element, it should take care of > the bound of the list. But should this be really part of the rule > definition? > > Many thanks in advance! > > Regards > > > > -- View this message in context: http://old.nabble.com/Need-help-in-formulating-rule-%28using-list%29-tp26... 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

Hi Wolfgang, thanks for your reply. I did have the idea about having the concepts of first, last,predecessor, successor etc. in TimeEntry. Unfortunately, it really isn't possible because this class (i.e TimeEntry) is a main part of a huge application model, which has been existing since long, has many dependencies to other classes, and shouldn't be changed ("only" for fulfilling the requirement of rules-engine) . So unfortunately I can only use those which are available to me. That's why I was hoping if there's really pure rule-based solution to this. Regards ________________________________ From: Wolfgang Laun <wolfgang.laun(a)gmail.com&gt; To: Rules Users List <rules-users(a)lists.jboss.org&gt; Sent: Wed, November 11, 2009 11:29:29 AM Subject: Re: [rules-users] Need help in formulating rule (using list) Implied by the List representation are concepts such as "first", "last", "predecessor" and "successor". All of these may or may not be represented by the fields in TimeEntry. This would be so if it is *guaranteed* that one TimeEntry's start time is another one's end time; (and then you wouldn't even need them being sorted). Failing this, an explicit representation by adding an ordinal number or (as I prefer doing) a reference to the previous and next TimeEntry might be considered. But, either way, reasoning over pairs of TimeEntry objects (of one Schedule) requires that they are all (at least temporarily) present as facts in WM. Then, to be identified as TimeEntrys of a specific Schedule, they also could have a reference to that. It's a simple task to write a rule that fires for a new Schedule and creates the extended TimeEntryPlus facts from its List<TimeEntry>. To avoid NPEs, I'd add a dummy TimeEntryPlus object (type=="OFF") before and after. Then, you could write rules rule checkValidBreak1 when     $break : TimeEntryPlus( type == "BREAK" )     TimeEntryPlus( type == "WORK", succ == $break || pred == $break, length <= 10 ) then   System.out.println( "Short work b/a break " + ... $break ..., $break.getSchedule() ... ) end rule checkValidBreak2 when     $break : TimeEntryPlus( type == "BREAK" )     TimeEntryPlus( type == "WORK", succ == $break ) then   System.out.println( "Can't start with a break " + ... $break ..., $break.getSchedule() ... ) end -W On Wed, Nov 11, 2009 at 10:46 AM, psentosa <psentosa(a)yahoo.com&gt; wrote: > > Hi Brody, > > I have had similar situation several times, and each time I had to modify > my > objects to avoid this, and it was really tedious. > I'd also would like to know whether it is possible to have a "real > solution" > in this case without needing to change the base objects, but rather use > the > rule language to formulate this kind of business rule > > *why didn't I receive this mail through the mailing list? maybe you > haven't > subscribed yet?* > > > > > Brody bach wrote: >> >> Hi all, >> >> I have an object which I use as main fact object, let's say "Schedule", >> which has a list of objects called "TimeEntry"  ---> >> >> class Schedule(){ >>      List<TimeEntry> entries; >> } >> >> class TimeEntry(){ >>      String type; >>      Date start; >>      Date end; >>      Integer length; >> } >> >> >> Now, if I insert Schedule into the WM, and would like to iterate over the >> list of TimeEntry, due to the following business rule : >> >> For all time entries, if it is of type BREAK: >> check whether a time entry of type WORK exist, >> before and/or after this BREAK, which has only length of 10 minutes >> >> The content of the time entry list has been sorted before so they are all >> in correct time order, e.g >> >> 09:00 - 09:10  WORK (10 min) >> 09:10 - 09:30  BREAK (20 min) >> 09:30 - 10:30  WORK  (60 min) >> --> in this case, the rule should fire >> >> How can I define this rule? Some questions which I have: >> - how do I check previous and next element of the current element? >> - the length of the list isn't fix; it may contain 1, 2, or more entries. >> So somehow in an attempt to access next element, it should take care of >> the bound of the list. But should this be really part of the rule >> definition? >> >> Many thanks in advance! >> >> Regards >> >> >> >> > > -- > View this message in context: > http://old.nabble.com/Need-help-in-formulating-rule-%28using-list%29-tp26... > 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 > _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users