[rules-users] FW: Basic rules question
Wolfgang Laun
wolfgang.laun at gmail.com
Tue May 10 08:10:03 EDT 2011
This isn't correct syntax: you cannot have a complex Java expression
on the left hand side of a contraints relational operator.
You might write this as
when
$conf : Configuration($category : category, eval(
$category.getCategoryId() != null ),
subCategories == null )
$subcats : ArrayList() from collect ( Category ( parent1 ==
($category. getCategoryId() ) ) )
then
2011/5/10 Abhay B. Chaware <Abhay.Chaware at kpitcummins.com>:
> I’ve written this rule to be fired for Configuration object whose category
> is selected and subcategories are yet not selected.
>
>
>
>
>
> rule "select sub categories"
>
> salience 50
>
> no-loop
>
> when
>
> $conf : Configuration($categoryId :
> $conf.getCategory().getCategoryId() != null, subCategories == null )
>
> $subcats : ArrayList() from collect (Category (
> parent1 == $categoryId ) )
>
> then
>
> $conf.setSubCategories($subcats);
>
> end
>
>
>
>
>
> but it gives me following error.
>
>
>
> [34,56]: [ERR 101] Line 34:56 no viable alternative at input ')' in rule
> "select sub categories" in pattern Configuration
>
> [34,57]: [ERR 102] Line 34:57 mismatched input '.' expecting ')' in rule
> "select sub categories" in pattern Configuration
>
> [34,74]: [ERR 102] Line 34:74 mismatched input '!=' expecting 'then' in rule
> "select sub categories" in pattern Configuration
>
>
>
> Do I need to use “eval” around the “$conf.getCategory().getCategoryId()”
> part ? Also in that case how do I get access to the property value ? It
> doesn’t support something like this :
>
>
>
> $conf : Configuration($categoryId : eval(
> $conf.getCategory().getCategoryId() != null ), subCategories == null )
>
>
>
>
>
> Regards,
>
> Abhay
>
> ________________________________
>
> From: rules-users-bounces at lists.jboss.org
> [mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Wendy Mungovan
> Sent: Tuesday, May 10, 2011 3:31 PM
> To: Rules Users List
> Subject: Re: [rules-users] FW: Basic rules question
>
>
>
> Abhay,
> You can use the normal Java gets (if your object has them).
>
>
> when
>
> $prod : Product ($prod.getMemory().getRam().getType() == "DDR")
>
> ...
>
> instead of $prod.getMemory()... you I think should also be able to use
> 'this.getMemory()....'
>
> (I have not tried these out to make sure)
>
> Wendy
>
>
>
> ________________________________
>
> From: Abhay B. Chaware <Abhay.Chaware at kpitcummins.com>
> To: Rules Users List <rules-users at lists.jboss.org>
> Sent: Mon, May 9, 2011 11:56:42 PM
> Subject: Re: [rules-users] FW: Basic rules question
>
> OK. Another one. How do I access and use a property of a member variable (
> object ) of an object, in rules ?
>
>
>
> e.g. in the same example, I need to check
>
>
>
> 1) if a product of type ‘laptop’ is inserted in memory AND
>
> 2) if the product’s MEMORY property ( object ) has an object of type DDR
> ram attached.
>
>
>
> In other words, here is the relationship of facts -
>
>
>
> PRODUCT has member variable MEMORY ( which is an object )
>
> MEMORY has member variable RAM ( which is again an object )
>
> RAM has member variable TYPE ( which should be equal to “DDR” )
>
>
>
> From within rules ‘when’ part, how do I check if there is a PRODUCT inserted
> in memory whose MEMORY has a RAM of type DDR assigned ?
>
>
>
> Regards,
>
>
>
> Abhay Chaware
>
> Sr. Designer | KPIT Cummins Infosystems Ltd | Board: +91 020 6652 5000 |
> Extn: 2989 | abhay.chaware at kpitcummins.com |www.kpitcummins.com
>
> P Please consider the environment before printing this e-mail
>
> ________________________________
>
> From: rules-users-bounces at lists.jboss.org
> [mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Michael Anstis
> Sent: Monday, May 09, 2011 4:27 PM
> To: Rules Users List
> Subject: Re: [rules-users] FW: Basic rules question
>
>
>
> Yes :)
>
> 2011/5/9 Abhay B. Chaware <Abhay.Chaware at kpitcummins.com>
>
> Mike,
>
>
>
> What I meant was, There are say 10 objects of RAM in memory whose type is
> DDR. Now my “Product” object has a member variable named “compatibleRAMs”,
> and I would like to set an arraylist containing these 10 objects to the
> “compatibleRAMs” variable of “Product” object in memory.
>
>
>
> I am reading about the “collect” which can be used to create collections
> from fact objects in memory. Something like.
>
>
>
> When
>
> $prod : Product (type==’laptop’)
>
> $compatibleRAMs : ArrayList() from collect (RAM (type == ‘DDR’))
>
> Then
>
> $prod.setCompatibleRAMs($compatibleRAMs);
>
>
>
> Am I on the right track ?
>
>
>
> -abhay
>
>
>
> ________________________________
>
> From: rules-users-bounces at lists.jboss.org
> [mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Michael Anstis
> Sent: Monday, May 09, 2011 3:52 PM
> To: Rules Users List
> Subject: Re: [rules-users] FW: Basic rules question
>
>
>
> Abhay,
>
> Do you need a list?
>
> You can assign RAM to COMPUTERS with this:-
>
> when
> $c : Computer( $type : type )
> $r : RAM( compatibleWith == $type )
> then
> $c.addRAM( $r );
> end
>
> This would add all RAM (in Working Memory) compatible with COMPUTER to
> computer.
>
> You could use a list of RAM as a Fact in WM and change your rule to use
> that:-
>
> when
> $l : MyList( )
> $c : Computer( $type : type )
> $r : RAM( compatibleWith == $type ) from $l
> then
> $c.addRAM( $r );
> end
>
> Or you can define a rule to construct the list too:-
>
> when
> $l : MyList( $t : typeRAM )
> RAM( $c : $t )
> then
> $l.add( $r )
> end
>
> I assume you'd need to differentiate different lists for different types; so
> I have shown use of "MyList" which could subclass ArrayList and have a "Type
> of RAM" attribute. Drools doesn't "do" generics.
>
> With kind regards,
>
> Mike
>
> 2011/5/9 Abhay B. Chaware <Abhay.Chaware at kpitcummins.com>
>
>
>
> 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 at lists.jboss.org
> [mailto:rules-users-bounces at 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
>
> Sr. Designer | KPIT Cummins Infosystems Ltd | Board: +91 020 6652 5000 |
> Extn: 2989 | abhay.chaware at kpitcummins.com |www.kpitcummins.com
>
> P Please consider the environment before printing this e-mail
>
> ________________________________
>
> From: rules-users-bounces at lists.jboss.org
> [mailto:rules-users-bounces at 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
>
>
>
> 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 at kpitcummins.com>
> To: "rules-users at lists.jboss.org" <rules-users at lists.jboss.org>
> Sent: Fri, May 6, 2011 4:59:46 AM
> Subject: [rules-users] Basic rules question
>
> Hi
>
>
>
> 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 )
>
> OR
>
> If selected product is “IBM T42”, then category “RAM” should have “512MB
> DDR” , “1024MB DDR”, “2048MB DDR” compatible. ( assigning individual items
> in rules )
>
> OR
>
> 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 ?
>
> OR
>
> 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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>
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>
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> or use this message or any part thereof. If you receive this message in
> error, please notify the sender immediately and delete all copies of this
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> virus infected mails.
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> This message contains information that may be privileged or confidential and
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> the person to whom it is addressed. If you are not the intended recipient,
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> or use this message or any part thereof. If you receive this message in
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