Applying Drools decision tables to 1-n data structures - drools

Question

I have the following classes, where there's a 1 - n relationship between Customer and Order, i.e. each Customer has many Orders
class Customer {
string identifier;
string country;
Collection orders;
}
class Order {
string identifier;
float amount;
}
class Report {
string identifier;
string country;
float amount;
}
I want to write the following in the form of one or more Drools decision tables.
For each Customer c
if c.country == US then
for each Order o
if o.amount > $10 then
create Report r
r.country = c.country
r.amount = o.amount
How possible is this using Drools decision tables?
When a Customer object meets the Customer condition, I then need to run each instance in the collection of Orders through the Order condition. If the order meets the condition, I need to create a report object that has values taken from the Customer and from the Order.

Answer 1

Drools will naturally iterate through collections.
This what your rule would look like in DRL:
rule "US Customer - Create Reports"
when
$customer: Customer( country == "US", $orders: orders != null )
$order: Order( amount > 10 ) from $orders
then
Report r = new Report();
r.country = $customer.country;
r.amount = $order.amount;
// TODO: do something with Report r here
end
This flattens naturally into a decision table in a very straight-forward fashion. You can even sub out the "US" (country) and 10 (amount) to variables.