DROOLS local variable assignment with nested members -


i having trouble assigning local variable nested members/objects in drools 6.2 , optaplanner 2 java classes. trying determine when 2 facts/instances nested members have same values. test case below simple, in reality i'm trying compare multiple nested members in rule.

public class {   private b x;   //public b getx(), public void setx(b b) follow ... }  public class b {   private int y;   //public int gety(), public void sety(int y) follow ... }  rule "testnestedmembers" when       a(x.y : y, $x : x)     a(x2.y == y, $x : x2)       scoreholder.addhardconstraintmatch(kcontext,-1000);      message [id=1, level=error,      path=org/somebody/project/planner/solver/planscorerules.drl, line=16, column=0    text=[err 102] line 16:49 mismatched input ':' in rule "testnestedmembers"]     message [id=2, level=error, path=org/somebody/project/planner/solver/planscorerules.drl, line=0, column=0 text=parser returned null package]     ---     warning messages:     ---     info messages:      @    org.optaplanner.core.config.score.director.scoredirectorfactoryconfig.buildkiebase(scoredirectorfactoryconfig.java:387)

i have reviewed answers, such as: drools rule expression : access nested class data member

and geoffrey de smet's answer illustrates conditional, not local assignment. i've tried different variations, no luck. thank advice.

edit: should have said creating binding instead of assigning local variable.

first i'll point out causes compiler errors.

rule "testnestedmembers" when       a(x.y : y, $x : x)     // (1)     a(x2.y == y, $x : x2)  // (2) (3)

(1) binding has form <variable> : <field>, x.y isn't valid variable name. (2) same x2.y. also, x2 isn't field in a. (3) nothing keeps rule engine matching same fact both patterns class a. means rule fire each , every fact of class a, since (as intend) a.x.y equal itself.

correct is

rule "testnestedmembers" when     $a1: a( $x1: x )     a( != $a1, $x2: x, $x1.gety() == $x2.gety() )      ...

however! rule fires twice, once 1 fact bound $a1, , once other (matching) 1 bound $a1. 1 possibility test existence of such pair (or cluster!):

rule "testnestedmembers" when     $a1: a( $x1: x )     exists a( != $a1, $x2: x, $x1.gety() == $x2.gety() )      ...

another option ensure ordering testing attribute:

rule "testnestedmembers" when     $a1: a( $x1: x, $id: id )     exists a( id > $id, $x2: x, $x1.gety() == $x2.gety() )

now fires each pair of a's second has greater (unique!) id.


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