CODEWITHSUNDEEP
javadroolsrule-enginerule
eduyayo
eduyayo

Reputation: 2038

How to declare a List in Drools rule

I've got a simple object construction. The class ContextDroolsObject has a property of type Map called objects. Inside that map there's a key "imageThemes" with an ArrayList and this rule here never matches:

import java.util.ArrayList;
import java.util.Map;
import com.my.ContextDroolsObject;

dialect 'java'


rule 'Soccer Image Theme'
    salience 100
    when
        s : ContextDroolsObject()
        objectsm : Map() from s.objects
         imageThemesList : ArrayList() from outputsm.imageThemes
    then
System.out.println("-----------------------soccer");
    end

I've also tried with List() with same result.

¿How to match the list declaration?

Upvotes: 2

Views: 5151

Answers (2)

jomarko
jomarko

Reputation: 267

Hi you can rewrite your rule in this way:

import java.util.ArrayList;
import java.util.Map;
import com.my.ContextDroolsObject;

dialect 'java'


rule 'Soccer Image Theme'
salience 100
when
    s : ContextDroolsObject( imageThemesList : objects#Map.get("imageThemes") )
then
    System.out.println("-----------------------soccer");
end

Upvotes: 2

laune
laune

Reputation: 31300

Using a hierarchical structure for fact objects is ver frequently a design flaw. You may not be able to reason conveniently over the list elements.

Anyway, this is the way to extract the list within the map from the ContextDroolsObject.

rule 'Soccer Image Theme'
  salience 100
when
  s: ContextDroolsObject() 
  imageThemesList: ArrayList() from s.getObjects().get( "imageThemes" )
then
  System.out.println("-----------------------soccer");
end

Upvotes: 1

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