[rules-users] Handling maps in Drools

[Manav]

Hi,

I am facing an issue with handling maps in LHS of drools. Appreciate your help with the same. 

I am using Drools version 5.1.


I have two maps where one is a reference map that contains certifications (key) and scores(value) required and other is map of user's actual certifications and scores. Objective is to find the certifications from users map based on keys in the reference map . Then for these certifications sum the score values and check if they cross the threshold. 

While trying to do the first step i am facing an issue . My rule looks like this :- 

rule "Map test"
when
    $rb : Certifications($reqCertificationKeys : requiredCertifications.keySet)
    $user : User($userCertifications : userCertifications)
    $arg : String() from $reqCertificationKeys    
    HashMap ($value : this[$arg] != null) from $userCertifications // Does not work 
then
    System.out.println ("Hash Map" + $arg);
end

However if i change the above line that has issues with below 

    HashMap ($value : this["Java"] != null) from $userCertifications // Works 

Is there a way to replace the key with a variable than with a fixed value ? Is it possible to iterate the second map with the key values that we get from the reference map ? 

Regards,
Manav