[rules-users] how to count distinct nested property?

Hi, I’m trying to wrap my head around how to use a combination of accumulate from and collect from to get a count of how many unique items there are of a nested child property and run the RHS of a rule if it’s > 1 So I have Many of Object A Each one contains An object B An object C Object C contains a nested child property So A +-+-B | +-C – property myId (many of these in the working memory) The rule I’m working with right now is rule "B must only be at 1 myId per day" when $b : B() $c : C() $aList : ArrayList (size > 1) from collect( A(b == $b, c.getDate() == $c.getDate()) ) eval ( RulesUtils.countIdsForC ($aList) > 1 ) then //fire some rules here end and the RulesUtils method is public static int countIdsForC (List aList) { Set<Integer> myIds = new HashSet<Integer>(); for (A a : aList) { myIds.add(a.getC().getMyId()); } return myIds.size(); } Now I’m well aware that this is sub-optimal, and indeed is firing lots of extra times and is really (Really) slow. I can vizualise that this should easily be possible with some combination of compound accumulate and collect statements, but for the life of me I can’t work out the correct arrangement (This is actually for use in an optaplanner ruleset so it will potentially be working on lots of data, over many iterations). Any suggestions on how to do this the way I know it needs to be, greatfully appreciated  -- View this message in context: http://drools.46999.n3.nabble.com/how-to-count-distinct-nested-property-t... Sent from the Drools: User forum mailing list archive at Nabble.com.