[rules-users] rules for promotional offers

[Wolfgang Laun]

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 at 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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