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

[richardhands]

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)
  {
SetInteger myIds = new HashSetInteger();
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 




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Re: [rules-users] Drools 6 Junit Random Failures

[richardhands]

Okay, after much investigation, it turns out the tests were A) using
.execute, rather than insert and fireallrules type behaviour, so i
refactored that to improve them a bit (gave me more control).

after that, and using the debug tools suggested it lead me to the root cause
of the problem.

someone when constructing the inbound facts had called
Calendar.getInstance() mutiple times, for different fields, which should
actually have been the same date/time, and hence sometimes the tests passed,
sometimes they failed.

sorted it now :-)



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