Very clean.
Earnie!
From: Steve Ronderos <steve.ronderos@ni.com>
To: Rules Users List <rules-users@lists.jboss.org>
Sent: Wed, July 21, 2010 9:56:56 AM
Subject: Re: [rules-users] collection question
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@lists.jboss.org wrote on 07/21/2010
01:59:40 AM:
> From:
>
> Wolfgang Laun <wolfgang.laun@gmail.com>
>
> To:
>
> Rules Users List <rules-users@lists.jboss.org>
>
> Date:
>
> 07/21/2010 02:02 AM
>
> Subject:
>
> Re: [rules-users] collection question
>
> Sent by:
>
> rules-users-bounces@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@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@lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/rules-users
> >
>
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