Wendy,

Thanks for helping me out so far.

I have another question. What if I have all my “RAM” objects inserted into working memory. How should I write my rule’s “when” portion to get a collection of all the RAM objects matching type “DDR” ? In other words, can I get collection of facts assigned to a variable and use it in the “then” part ?

Thanks

Abhay

==================================

From: rules-users-bounces@lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Wendy Mungovan
Sent: Friday, May 06, 2011 5:47 PM
To: Rules Users List
Subject: Re: [rules-users] Basic rules question

Q2:
So the rule would be something like:

rule "RAM type"
when
     $product: Product(type == "laptop");
then
     //you are looking for the best way to set valid RAM types in the then part of the rule?
    $product.setRamType("DDR");
    //or
   $product.setValidRamOptions( getValidRamOptions("DDR"));
end

where getValidRamOptions would be a custom function included through 'import function' so you can then load the choices from some where else. Or if RamOptions were an object in memory you could have a rule like:

rule "RAM type"
when
     $product: Product(type == "laptop");
     $ramOptions: RAMOptions(type == "DDR");

then
   $product.setValidRamOptions( $ramOptions.getList());
end

Wendy

==================================

Regards,

Abhay Chaware

P Please consider the environment before printing this e-mail

Abhay,
Q1: I think that this will depend on how many different products you have. If there is a small number it is more straight forward to have a rule for each one (so the 2nd option). This allows all you logic to be in one place. If there are a large number of products and writing a rule for each one is intractable you probably would want to look into some generalizations of the rules. Is that helpful?

Q2: I'm not quite sure what you are getting at in Q2. Are you trying to write validation rules or rules that are modifying the facts?

Wendy

From: Abhay B. Chaware <Abhay.Chaware@kpitcummins.com>
To: "rules-users@lists.jboss.org" <rules-users@lists.jboss.org>
Sent: Fri, May 6, 2011 4:59:46 AM
Subject: [rules-users] Basic rules question

I am a newbie to rule based applications and trying to get the concept of rules. I have couple of questions about rules to start with, not specifically about Drools though.

Q1 - Should rules be data/model specific or can/should they be generic or both

==========================================================

e.g.

If selected product “TYPE” is “laptop”, then category “RAM” should have all “DDR” type items compatible ( selecting items matching certain property )

If selected product is “IBM T42”, then category “RAM” should have “512MB DDR” , “1024MB DDR”, “2048MB DDR” compatible. ( assigning individual items in rules )

Combination of both

Q2 – How should be the data modeled in above case

==========================================================

e.g.

in product master, each item ( e.g. T40, T42 ) should have a “TYPE” ( e.g. desktop or laptop ) , all items in category “RAM” should have a “TYPE” ( e.g. DDR ) and then control the assignment of RAM options to the PRODUCT through Rule using “DDR” type ?

in product master, each item ( e.g. T40, T42 ) should have a “TYPE” ( e.g. desktop or laptop ) , all items in category “RAM” should have a “compatibleProduct” column ( e.g. desktop or laptop ) and control the assignment of RAM to PRODUCT through “dynamic” rules by selecting all the RAMs by passing the “TYPE” of the product to the database handler.

Am I making my point clear ?

Thanks

Abhay

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