[rules-users] collection question

[Steve Ronderos]

Hi J,

In your example I don't think that the collect is necessary.

I believe the following will work:

rule "AddBonusCd"

  when
    $so : ShippingOrder()
    Product(name == "cd1") from $so.products
    not (Product(name == "bonus_cd") from $so.products)
  then
    System.out.println("Adding Bonus Cd");
 
    Set<Product> productSet = new HashSet<Product>($so.getProducts());
 
    Product bonusCd = new Product();
    bonusCd.setName("bonus_cd");
    productSet.add(bonusCd);
 
    modify($so) {
      setProducts(productSet);
    }
end

You don't need the collects because you are just checking for 
existence/non-existence of facts within the products collection.

Good luck!
Steve


rules-users-bounces at lists.jboss.org wrote on 07/21/2010 01:59:40 AM:

> From:
> 
> Wolfgang Laun <wolfgang.laun at gmail.com>
> 
> To:
> 
> Rules Users List <rules-users at lists.jboss.org>
> 
> Date:
> 
> 07/21/2010 02:02 AM
> 
> Subject:
> 
> Re: [rules-users] collection question
> 
> Sent by:
> 
> rules-users-bounces at lists.jboss.org
> 
> Things would be smpler if you could avoid re-creating Product objects
> because adding an identical Object does not change the Set. (This
> could be implemented with the help of a global Map<String,Product>,)
> 
> Second, overriding equals (and hashCode) in Product would also avoid 
adding
> an "evil twin" in your rule code - as it is!
> 
> Even simpler is a solution where the relevant Product objects are 
inserted
> as facts, so that
>    $cd1 : Product( name == "cd1" )
>    $bonus_cd : Product( name == "bonus_cd" )
>    $order : ShippingOrder( products contains $cd1, products not
> contains $bonus_cd )
> is true (again, with equals and hashCode being overridden).
> 
> Given your solution with collect, an additional eval testing for
> "bonus_cd" not being the
> name of the single Product in List $productList might be more
> efficient than iterating
> all products a second time.
> 
> -W
> 
> On 21 July 2010 00:41, javaj <jmilliro at ameritech.net> wrote:
> >
> > I'm trying to write a rule to add an object to a collection if 
thecollection
> > already contained a certain object with a specific attribute.
> >
> > I developed a small example so maybe that will make more sense:
> >
> > Use Case: In a product shipping applicaiton, anytime a product with 
the name
> > "cd1" is in the shipping order, a bonus product named "bonus_cd" needs 
to be
> > added to the shipping order.  The bonus cd should not be added if it's
> > already in the shipping order.
> >
> > Shipping Order:
> >
> > public class ShippingOrder {
> >
> >        private Set<Product> products;
> >
> >        public ShippingOrder() {}
> >
> >        public Set<Product> getProducts() {
> >                return products;
> >        }
> >
> >        public void setProducts(Set<Product> products) {
> >                this.products = products;
> >        }
> >
> > }
> >
> > Product:
> >
> > public class Product {
> >
> >        private String name;
> >
> >        public Product(){}
> >
> >        public String getName() {
> >                return name;
> >        }
> >
> >        public void setName(String name) {
> >                this.name = name;
> >        }
> >
> > }
> >
> >
> > Rule:
> >
> > rule "AddBonusCd"
> >
> >        when
> >                $so : ShippingOrder()
> >                $productList : ArrayList(size == 1) from collect( 
> Product(name matches
> > "cd1|bonus_cd") from $so.products)
> >        then
> >                System.out.println("Adding Bonus Cd");
> >
> >                Set<Product> productSet = new HashSet<Product>
> ($so.getProducts());
> >
> >                Product bonusCd = new Product();
> >                bonusCd.setName("bonus_cd");
> >                productSet.add(bonusCd);
> >
> >                modify($so) {
> >                        setProducts(productSet);
> >                }
> > end
> >
> > The Shipping Order object is inserted as the fact.
> >
> > The rule is valid if only cd1 or cd_bonus is in the shipping order.  I 
only
> > want the rule to run when cd1 is in the product set but cd_bonus is 
not.
> > Makes sense?
> >
> > Thanks,
> > J
> > --
> > View this message in context: http://drools-java-rules-engine.
> 46999.n3.nabble.com/collection-question-tp982769p982769.html
> > Sent from the Drools - User mailing list archive at Nabble.com.
> > _______________________________________________
> > rules-users mailing list
> > rules-users at lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/rules-users
> >
> 
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