[rules-users] Collecting all items of nested collections / accumulate nested collections

[Wolfgang Laun]

If I understood it correctly and have not missed a comma or parenthesis:

rule "level three"
when
   $l0: Level0()
   $list1: List( size > 0 )
      from accumulate (Level1( $level1List: level1List) from $l0.level1List,
        init( List l = new ArrayList(); )
        action( l.addAll($level1List); )
        return( l ) )
   $date: PartialDate()
      from accumulate (Level2((name in ("name1", "name2"),$occurrence:
occurrence) from $list1,
          maxDate($occurence) )
then

-W


2011/10/5 Claes, Kenny [JRDBE - Non J&J] <kclaes at its.jnj.com>
>
> I have a question regarding creating a list of items that are all in
nested collections of my main object.
>
> A high level overview of the model is like this:
>
>
>
> public Level0 {
>  private List<Level1> level1List;
> }
>
>
>
> public Level1 {
>  private List<Level2> level1List;
> }
>
>
>
> public Level2 {
>  private Date occurence;
> }
>
>
>
> Now, I add objects of type 0 in the working memory and for each of those
objects, I want to find the latest occurrence of a certain Level2,
regardless of which level1 they belong to.
>
>
>
> If there’s only 2 levels and I want to find the latest occurrence of
Level2’s with a certain name, I can write:
>
>
>
> rule "latest level 1"
>
> when
>
>     $l0: Level0()
>
>     $date: Date() from accumulate (Level1(name in ("name1", "name2"),
$occurence: occurence) from $l0.level1List, maxDate($occurence))
>
> then
>
>       // register fact that latest occurrence of name1/name2 level1 was on
$date
>
> end
>
>
>
> Now, with 3 levels, since I obviously can’t replace $l0.level1List with
$l0.level1List.level2List, is there a way to create an intermediate list
that will contain all Level2 objects? No filtering needs to take place on
Level1, but if there’s a way to do that too, that would be nice.
>
>
>
> What I currently have is this:
>
>
>
> rule "latest level 2"
>
> when
>
> $l0: Level0()
>
> $l1: Level1() from $l1.level1List
>
> $l2List: List(size > 0) from collect( Level2(name in (("name1", "name2"))
from $l1.level2List )
>
>       $date: PartialDate() from accumulate (Level2( $occurence: occurence)
from $l2List, maxDate($occurence))
>
> then
>
>       // register fact that latest occurrence of name1/name2 level2 was on
$date
>
> end
>
>
>
> But this does not work as it treats each Level1 seperately: it creates a
“latest occurrence” for all accumulated level2 facts within a level1,
instead of one for the entire set of level 2’s ‘owned’ by the level0 object.
>
>
>
> Any suggestions?
>
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