[jboss-jira] [JBoss JIRA] (DROOLS-435) ClassCastException using nested accumulates

[Mario Fusco (JIRA)]

     [ https://issues.jboss.org/browse/DROOLS-435?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mario Fusco resolved DROOLS-435.
--------------------------------
    Resolution: Won't Fix


> ClassCastException using nested accumulates
> -------------------------------------------
>
>                 Key: DROOLS-435
>                 URL: https://issues.jboss.org/browse/DROOLS-435
>             Project: Drools
>          Issue Type: Bug
>    Affects Versions: 5.6.0.Final, 6.0.1.Final
>            Reporter: Mario Fusco
>            Assignee: Mario Fusco
>            Priority: Critical
>
> Supposing I have a data model as the following
> {code}
>     public static class Driver {
>         private final String name;
>         private List<Car> cars = new ArrayList<Car>();
>         public Driver(String name) { this.name = name; }
>         public String getName() { return name; }
>         public void addCar(Car car) { cars.add(car); }
>         public List<Car> getCars() { return cars; }
>     }
>     public static class Car {
>         private final int speed;
>         public Car(int speed) { this.speed = speed; }
>         public int getSpeed() { return speed; }
>     }
> {code}
> where each Driver can own multiple cars. I would like to calculate the average of the speed of all the Cars as I did with the following nested accumulates 
> {code}
>     @Test
>     public void testNestedAccumulate() {
>         String str =
>                 "import java.util.*;\n" +
>                 "import " + Driver.class.getCanonicalName() + ";\n" +
>                 "import " + Car.class.getCanonicalName() + ";\n" +
>                 "rule R when\n" +
>                 "accumulate ( Car( s: speed ) from accumulate ( Driver( c: cars ), " +
>                 "                                               init(List list = new ArrayList();)," +
>                 "                                               action(list.addAll(c);)," +
>                 "                                               reverse(list.removeAll(c);)," +
>                 "                                               result(list) ),\n" +
>                 "                               avg: average(s) )\n" +
>                 "then\n" +
>                 "    System.out.println( avg );\n" +
>                 "end\n";
>         KnowledgeBase kbase = loadKnowledgeBaseFromString(str);
>         StatefulKnowledgeSession ksession = kbase.newStatefulKnowledgeSession();
>         Driver mario = new Driver("mario");
>         mario.addCar(new Car(100));
>         mario.addCar(new Car(200));
>         Driver mark = new Driver("mark");
>         mark.addCar(new Car(300));
>         mark.addCar(new Car(400));
>         ksession.insert(mario);
>         ksession.insert(mark);
>         ksession.fireAllRules();
>     }
> {code}
> Note that splitting the nested accumulate in 2 separated accumulates as it follows fixes the problem.
> {code}
>     @Test
>     public void testAccumulates() {
>         String str =
>                 "import java.util.*;\n" +
>                 "import " + Driver.class.getCanonicalName() + ";\n" +
>                 "import " + Car.class.getCanonicalName() + ";\n" +
>                 "rule R when\n" +
>                 "$cars : List() from accumulate ( Driver( c: cars ), " +
>                 "                                 init(List list = new ArrayList();)," +
>                 "                                 action(list.addAll(c);)," +
>                 "                                 reverse(list.removeAll(c);)," +
>                 "                                 result(list) )\n" +
>                 "accumulate ( Car( $s: speed ) from $cars,\n" +
>                 "             $avg: average($s) )\n" +
>                 "then\n" +
>                 "    System.out.println( $cars );\n" +
>                 "    System.out.println( $avg );\n" +
>                 "end\n";
>         KnowledgeBase kbase = loadKnowledgeBaseFromString(str);
>         StatefulKnowledgeSession ksession = kbase.newStatefulKnowledgeSession();
>         Driver mario = new Driver("mario");
>         mario.addCar(new Car(100));
>         mario.addCar(new Car(200));
>         Driver mark = new Driver("mark");
>         mark.addCar(new Car(300));
>         mark.addCar(new Car(400));
>         ksession.insert(mario);
>         ksession.insert(mark);
>         ksession.fireAllRules();
>     }
> {code}



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