On Fri, Sep 9, 2011 at 12:40 PM, Sandeep Bandela <gibsosmat@gmail.com> wrote:

Hi Wolfgang,
This is what I did initially but for product > 2 I didnt find a generic way to do this. following is my first rule. I didnt use field names because it was giving error that member is not accessible. I will attach the errors of each case in a few mins.

rule "Apply 10% discount if you purchase 2 items"
    dialect "java"
    when
        $s1 : CartItem( getProductId() == 236061, !isProcessed())
        $s2 : CartItem( getProductId() == 236061, getId() != $s1.getId(), !isProcessed())
        $m : RuleMessage()
then
        $m.addMessage("Found item1: " + $s1.getName() + " id: "+$s1.getId());
        $m.addMessage("Found item2: " + $s2.getName() + " id: "+$s2.getId());
        modify($s1){
        setProcessed(true),
        setPromoItemDiscount($s1.getPrice() * 0.1),
        setPromoId("1"),
        setBundleId(bundler.getId()),
        setAggrigatorId(1)
        };
        modify($s2){
        setProcessed(true),
        setPromoItemDiscount($s2.getPrice() * 0.1),
        setPromoId("1"),
        setBundleId(bundler.getId()),
        setAggrigatorId(1)
        };
        bundler.increment();
end

2011/9/9 Wolfgang Laun <wolfgang.laun@gmail.com>

Your rule exhibits procedural thinking. (For an aspiring rule programmer his is typical teething troubles.)

There's no need to collect all A's and B's in order to determine their number being greater than one or two - this is achieved automatically by a simple triple match rule. Consider

rule "2A - 1B"
when
   $a1: CartItem( productId == "A", processed == false )
   $a2: CartItem( this != $a1, productId == "A", processed == false )
   $b: CartItem( productId == "B", processed == false )
then
   modify( $a1 ){...}
   modify( $a2 ){...}
   modify( $b ){...}
end

Note:
The modify is essential. (When you say "doesn't work", always provide details.)
Use the field name rather than the getter call - it improves readability.

I'm not sure whether 5.2.0 final handles boolean fields correctly - IIRC, there were some issues. It's possible that CartItem(..., !processed) works.
-W

2011/9/8 Sandeep Bandela <gibsosmat@gmail.com>

Hi,
I am new to rules engine, after going through the examples shipped (shopping.drl, petstore.drl)
I am trying to implement promotional discounting using drools 5.2.0 final, stateful session. assume cart has all the items that customer wants to buy,
I am trying to bundle them together with the existing offers

rule "Buy X units of Product A and Get Y units of Product B Free"
    dialect "java"
when
    $itemsA : ArrayList( size >= 2) from collect( CartItem( getProductId() == "A", !isProcessed()))
    $itemsB : ArrayList( size >= 1) from collect( CartItem( getProductId() == "B", !isProcessed()))
then
    // current scenario buy 2*A and get 1*B
    int x = 2;
    int y = 1;
    for(int i=0 ; i < x ; i++){
        CartItem $ci = (CartItem) $itemsA.get(i);
        // modify($ci){setProcessed(true) ... } dosent work
        $ci.setProcessed(true);
        $ci.setItemDiscount(0.0);
        $ci.setBundleId(bundler.getId());
    }

    for(int i=0 ; i < y ; i++){
        CartItem $ci = (CartItem) $itemsB.get(i);
        $ci.setProcessed(true);
        $ci.setItemDiscount($ci.getPrice());
        $ci.setBundleId(bundler.getId());
    }
    // global counter to identify bundled items
    bundler.increment();
end

the above rule calculates only for 1 set of offer i.e first 2*A & 1*B are considered, rest in the cart are not bundled.
if customer buys 4*A + 2*B it dosent consider it. am I missing anything? is this the right way to do it?
any feedback is appreciated.

--
Regards,
Sandeep Bandela.

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--
Regards,
Sandeep Bandela.