Look up "Conditional Element collect" in the manual. That provides example code for getting a list of matching facts.

For more complex tasks, there's "accumulate".

Steve

On 11 Apr 2013, at 17:51, Alex Burman <alexburman@gmail.com> wrote:

Continuing with this same example, How can I count the number of times a student has received an A across all the classes?

I can get it to trigger each time a student appears in the rosters of 2 different teachers and that student has an A in both but I can't figure out how to track it across more then that.

On Fri, Apr 5, 2013 at 4:50 AM, Stephen Masters <stephen.masters@me.com> wrote:

Just thought I'd mention that I hadn't replied to this, because it looks way too much like comp-sci homework. Not sure whether that's the same reason others haven't replied either. ;)

A hint though to get you started. You can probably use something like...

$student: Student(grade != null) from $roster

… with a few lines before that to pick out the roster in a similar fashion.

To understand it, check out the Drools Expert manual for the "from" operator for working with lists/collections.

Steve

On 3 Apr 2013, at 19:59, burmanator <alexburman@gmail.com> wrote:

> So the example I am working with is this:
> You have a Teacher object
>     that stores a list of Rosters  objects
>           in each Roster is a list of Students objects
>                each Student has a grade value
>
> How would I go about creating a rule to find all the students that got As
> for a given Teacher across all her Rosters?
>
>
>
> --
> View this message in context: http://drools.46999.n3.nabble.com/creating-a-rule-regarding-an-element-of-list-stored-in-an-object-in-a-list-tp4023205.html
> Sent from the Drools: User forum mailing list archive at Nabble.com.
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--
Sincerely,
Alex Burman
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