[rules-users] General rules in spreadsheet.

[tom ska]

Thomas,
as far as I understood, I don't have to use update(p), to update it :) After
using update method, there is infinite loop in my rules (I am talking about
DRL).

# this method doesn't change CProduct object
rule "Case A"
salience 1
activation-group "g1"
    when
        p : CProduct( name == "A" )
    then
        System.out.println("Special product: " + p.getName());
end

# this method doesn't change CProduct object
rule "Case B"
salience 1
activation-group "g1"
    when
        p : CProduct( name == "B" )
    then
        System.out.println("Special product: " + p.getName());
end

# this method changes CProduct object
rule "Case general"
salience 0
activation-group "g1"
    when
        p : CProduct(  )
    then
        p.setValue(1000);   # changes object's value
                                    # I don't use update()
        System.out.println("Normal product: " + p.getName());
end

# this method changes CProduct object
rule "New rule"
salience 0          # lower salience
activation-group "g1"
    when
        p : CProduct(  )
    then
        p.setValue(-1);      # I change object's value
                                   # I don't use update()
        System.out.println(p.getName() + " " + p.getValue());
end

In program, I use StatelessKnowledgeSession and execute method to use rules
on CProduct. And.... All normal products (name != A && name != B) have value
1000. Not -1. I don't use update function.

So: I use rules that update my object, but I don't get what am I to watch
out... For each object my activation-group fires only one rule. Rule "New
rule" never fires.

Thanks,
tom.



2010/7/28 Swindells, Thomas <TSwindells at nds.com>

>  There are two other solutions if you do need the p:
>
> 1.       Change your condition to be “name matches $param”, this will
> match as a regular expressions. Your general case can then be “.*”.
>
> 2.       Merge your  p:CProduct across two columns. Have a condition of
> “this != $param” for the first column and give all the rows in this column
> the value of null. Your second column can be name and then be missing in the
> general clause. For the general clause this will evaluate to:
>
> rule "Case general"
> salience 0
> activation-group "g1"
>     when
>         p : CProduct( this != null  )
>
>     then
>         System.out.println("Normal product: " + p.getName());
> end
>
> which obviously will always evaluate to true for any CProduct.
>
>
>
> The other general thing you need to watch out for with a spreadsheet of
> this form is if you have any rules which update CProduct as these rules
> would then be re-evaluated and re-executed again.  In particular if you have
> any rules of a lower salience that update the name then the activation group
> doesn’t stop a different rule from being fired – activation groups are only
> mutually exclusive at a given point in time when the activation occurs, they
> don’t prevent different later re-activations.
>
>
>
> Thomas
>
>
>
> *From:* rules-users-bounces at lists.jboss.org [mailto:
> rules-users-bounces at lists.jboss.org] *On Behalf Of *Mauricio Salatino
> *Sent:* 28 July 2010 04:58
> *To:* Rules Users List
> *Subject:* Re: [rules-users] General rules in spreadsheet.
>
>
>
> you can remove p, because in the spreadsheet you are not using it..
> in the rules you use p to print the type of the product but in the
> spreadsheet you are hardcoding the value in the "what to print" column
>
> 2010/7/27 tom ska <tiberium.linux at gmail.com>
>
> Hello,
> I want to use StatelessSession with spreadsheet. I wrote few rules in DRL,
> but I cant do it in spreadsheet. First I want to present rules and class
> that is used by rules:
>
> public class CProduct {
>
>     private String name;
>     private int value;
>
>     public CProduct ()
>     {
>         name = "empty";
>         value = 0;
>     }
>
>     public CProduct (String name, int value)
>     {
>         this.name = name;
>         this.value = value;
>     }
>
>     public String getName() {
>         return name;
>     }
>     public void setName(String name) {
>         this.name = name;
>     }
>     public int getValue() {
>         return value;
>     }
>     public void setValue(int value) {
>         this.value = value;
>     }
> }
>
> Rules:
>
> rule "Case A"
> salience 1
> activation-group "g1"
>     when
>         p : CProduct( name == "A" )
>     then
>         System.out.println("Special product: " + p.getName());
> end
>
> rule "Case B"
> salience 1
> activation-group "g1"
>     when
>         p : CProduct( name == "B" )
>     then
>         System.out.println("Special product: " + p.getName());
> end
>
> rule "Case general"
> salience 0
> activation-group "g1"
>     when
>         p : CProduct(  )
>     then
>         System.out.println("Normal product: " + p.getName());
> end
>
> Using stateLessSession, salience, and activation-group I can determine,
> that only one rule is going to be fired for each CProduct. And with salience
> param, I can determine priority (it is important to get special products
> first).
> Now I am going to write those rules in spreadsheet. But I can't define rule
> "Case general".
>
>
>
> CONDITION
>
> ACTION
>
> ACTIVATION-GROUP
>
> PRIORITY
>
>
>
> p:CProduct
>
>
>
>
>
>
>
>
>
> name
>
> System.out.println("$param");
>
>
>
>
>
> Rules names
>
> Product name
>
> what to print
>
>
>
>
>
> Case A
>
> A
>
> Special A
>
> G1
>
> 1
>
> Case B
>
> B
>
> Special B
>
> G1
>
> 1
>
> General case
>
> normal
>
> G1
>
> 0
>
>
> But when I am going to use the spreadsheet, I get this error:
>
> "p cannot be resolved"
>
> Problem disappears, when I fill "Product name" in "General case".
>
> But I want it to be empty, because I want to fire rule "General case" when
> rules "Case A" & "Case B" won't fire for any object's name.
>
> Thanks, Tom.
>
>
>
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