Thanks, that sounds logical to me. I guess I just have to "trust" that
the rule where the array gets initialised activates earlier than the
rule where I need the array. That shouldn't be a problem since I use
salience and to avoid nullpoint exceptions I can use the if(objectList
!= null) in the "Then" part of the rule where I need the array.
Maybe an idea for the drools developers to create an "update" function
for the globals so we can eval on them too...in the future.
vdelbart schreef:
It's normal.
Globally, the rule engine works in two steps :
- first : the activation (the "when" statement)
- second : the execution (the "then" statement) with salience, ruleflow ...
In your test, you have in the first step objectList = null and in the second
step objectList = [1, 2].
If you want to re-activate your rule, you have to do an update/insert/remove
action... But you can't do that with globals. So you need to use the WM
facts.
Waruzjan Shahbazian-2 wrote:
I have the same "problem", but eval(objectList == null) doesn't work. If
I don't execute "drools.getWorkingMemory().setGlobal()" it "works fine",
as if the rule activates and the object is null.
global List objectList;
rule "Start"
salience 101
when
#conditions
then
objectList = new ArrayList() ;
objectList.add("1");
objectList.add("2");
System.out.println("Start objectList:"+objectList);
//drools.getWorkingMemory().setGlobal("objectList", objectList);
end
rule "end"
salience 97
when
eval (objectList == null)
then
System.out.println("End objectList: "+objectList);
end
gives:
Start objectList:[1, 2]
End objectList: null
Next I uncomment the "drools.getWorkingMemory().setGlobal("objectList",
objectList);" and run the rule again an get:
Start objectList:[1, 2]
End objectList: [1, 2]
so the objectList isn't null, but the rule still activates...
Kris Verlaenen schreef:
That initialized my global but the rule still runs every execution.
Can I
disable the rule after the first execution?
What do you mean by "every execution". A rule should only be executed
once, unless it gets reactivated (which should not be the case in this
situation).
I would like to use (if (objectList==null)). My list is not
immutable. Can
I make a similar rule for the LHS?
You can test whether the global is null using eval( objectList == null
) in the LHS of the rule.
Kris
_______________________________________________
rules-users mailing list
rules-users@lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users
_______________________________________________
rules-users mailing list
rules-users@lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users
_______________________________________________
rules-users mailing list
rules-users@lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users
