Regis,

   You are probably having problems with mutable predicates, when using "subject.allocatedDays". As a first step to understand your problem, I strongly encourage you to make constraints flat, i.e., avoid using nested accessors. After you get used to what can and what can't be done, you can go back to use nested accessors.
   Also, I suggest you use modify() block instead of update():

rule

"allocate"

when

$lesson : Lesson(allocated == false, session.type == Session.DISTINCT )

$subject : Subject( $allocatedDays : allocatedDays ) from $lesson.subject

$availableHour : Hour(allocated == false, day not memberOf $allocatedDays)

then

modify( $lesson) {

    setHour($availableHour ),

    setAllocated(true)

}

modify( $availableHour )

    setSubject($lesson.getSubject()),

    setAllocated(true )

}

end


    Hope it helps.

    []s
    Edson
 
2008/4/14 Piccand, Regis <rpiccand@verisign.com>:
Hi all,
 
I am evaluating Drools and am stuck with a simple rule that selects elements which do not correspond to the condition... Since I am updating objects in the RHD, I guess it has to do with my wrong understanding (and the cache...?)
 
 
I am trying to allocate lessons to periods (hour). My object model can be summarize is as follows :
 
Lesson
    boolean : allocated    // true if the lesson has been allocated to an hour
    int : session             // a session is a bunch of lessons
    Subject : subject    // an allocated lesson is assigned a subject
 
Subject
    Set<Day> : allocatedDays // days in which this subject is taught - checked before allocation, as a subject can only be taught once a day
 
Hour
    boolean : allocated // true is this hour has been allocated with a lesson
    Day : day // the day this hour belongs to - required to check with subject.allocatedDays
 
 
I put in the workingMemory a bunch of Lesson objects, which have been set with Subject and Session id. I also put a bunch of Hour object, set with a Day.
 
 
My rule is as follows:
 

rule

"allocate"

when

$lesson : Lesson(allocated == false, session.type == Session.DISTINCT, $allocatedDays : subject.allocatedDays)

$availableHour : Hour(allocated == false, day not memberOf $allocatedDays)

then

$lesson.setHour($availableHour ) ;

$lesson.setAllocated(true) ;

update($lesson);

$availableHour.setSubject($lesson.getSubject()) ;

$availableHour.setAllocated(true );

update($availableHour);

end

When I set a debug on the first line of the THEN section, I can see that sometimes $availableHour.allocated == true ... sometimes $lesson.allocated == true (although it's an implicit And statement ...)

Therefore, I can see that the update() works, but it seems that the rule does not use the updated object (due to shallow copy ??)

Any help more than welcome

Regis

 


_______________________________________________
rules-users mailing list
rules-users@lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users




--
Edson Tirelli
JBoss Drools Core Development
Office: +55 11 3529-6000
Mobile: +55 11 9287-5646
JBoss, a division of Red Hat @ www.jboss.com