Thank you Edson, this helps me get going in the right direction.

In this logic:

Period( $sd : startDate, $ed : endDate )
    Number( intValue > 10 ) from accumulate(
         Day( date >= $sd && <= $ed, status == Day.WORKED ),
         count( 1 ) )

Where is date coming from? As I read the statements, I am getting startDate and endDate from a Period object that I pass in. The Number() statement just says to take the result and parse it as a number right? What about Day and date though? Is Day a java object from my Java code? I searched the docs looking for a Day object in the drools docs and didn't come up with anything. I am assuming it is because of the Day.WORKED status, would date just be a member of that object?

Thanks,

Bryan

On Mon, Nov 3, 2008 at 7:51 PM, Edson Tirelli <tirelli@post.com> wrote:

   Bryan,

   The main decision here is how to do Date arithmetic, since java does not provide easy to use APIs for that. So, the simplest way IMO, from a rule authoring perspective, is to have a "constraint object" that contain both boundary dates of your rule. Lets call it "Period".
   So, if you want to write your rule saying:

"Take a break if you worked more than 10 days in the given period."

    Just do:

rule "take a break"
when
    Period( $sd : startDate, $ed : endDate )
    Number( intValue > 10 ) from accumulate(
         Day( date >= $sd && <= $ed, status == Day.WORKED ),
         count( 1 ) )
then
    // take a break
end

    If your Day object is some kind of container object, use a chained from to iterate over them:

rule "take a break"
when
    Period( $sd : startDate, $ed : endDate )
    DailyReport( $days : days )
    Number( intValue > 10 ) from accumulate(
         Day( date >= $sd && <= $ed, status == Day.WORKED ) from $days,
         count( 1 ) )
then
    // take a break
end

   Hope it helps.

     Edson

2008/11/3 Bryan Hansen <bryankhansen@gmail.com>

Not really sure how to go about writing this in a rule or whether or not the logic belongs in a rule (I think it does, but if you don't please comment as to why).

I have a list of objects that contain date objects. If the list contains 10 objects that date are before mine then I want them to take a break.

The business case is similar to that of an HR system. If they have worked too many days out of the last 12 then they need to take a break.

I am guessing it would have to use the "collect" attribute, but how would you do the date logic in a LHS clause?

Thanks for any guidance on this.

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--
 Edson Tirelli
 JBoss Drools Core Development
 JBoss, a division of Red Hat @ www.jboss.com

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