I'm not sure if it is possible or not but personally I wouldn't do it.
I would have both Order and CustomerOrder as facts within your knowledge base
(and probably orderItem as well).
I would add a total field to Order and write a rule to maintain this value by
accumulating the itemAmount of all the orderitems. Similarly I would have
another rule on CustomerOrder to accumulate the value of the total of each of
the orders. When an Order is updated this would automatically trigger the
re-calculation of the CustomerOrder total.
Seperately I would have rules written against these fields which are then
trivial to write and will make it much easier to cater for future requirements
(eg in the future if customer name is Mr Rich then allow a max order value of
XYZ).
If you can't modify your core objects then you can also implement it by having
a separate fact which links the object (CustomerOrder or order) to the order
value) eg ValueFact (source, value).
Thomas
Ps.
It is a really bad idea to try and use doubles to store currency amounts.
Doubles do not store decimal numbers precisely, this means £0.30 may actually
be stored as 0.30004, and if you keep add £0.10 100 times you may
end up with £9.99 not £10.00. You should either use integer numbers (store
pence not fractions of pounds) or use big decimal.
http://www.velocityreviews.com/forums/t139008-java-double-precision.html shows
the problem in action.
-Original Message-
From: rules-users-boun...@lists.jboss.org [mailto:rules-users-
boun...@lists.jboss.org] On Behalf Of Dinesh kumar
Sent: 06 August 2010 11:58
To: rules-users@lists.jboss.org
Subject: [rules-users] Is nested loops possible ?
Hi,
I am having a problem in iterating a list inside a list.
I am having the following business scenario.
Public Class CustomerOrder {
private String customerName;
private ArrayListOrder orderList;
}
Public Class Order {
private String orderId;
private String orderTime;
private ArrayListOrderItem orderList;
}
Public Class OrderItem {
private String itemName;
private Double itemAmount;
}
I need to find the total order amount for each order and the sum of all
order.
My rule is like individual orders should not exceed a 1 and total order
amount of all customers should not exceed 10.
For this, I need to iterate ArrayListOrder orderList and during each
iteration , I need to iterate ArrayListOrderItem orderList. Is this
possible in Drools ?
I tried something like this. But it doesn't seem to be working.
when
ClaimRegistration($orderList: orderList)
Number( $count : intValue 0)
from accumulate(Order(orderId== order1
Number( doubleValue 1 )
from accumulate( OrderItem( $value : itemAmount),
init( double total = 0; ),
action( total += $value; ),
reverse( total -= $value; ),
result( total ) )
) from $orderList,count(1))
then
Sysout(,);
It would be of great help if any one can give suggestions to solve this.
Is nested loops possible in Drools ?
Regards,
Dinesh
--
View this message in context: http://drools-java-rules-
engine.46999.n3.nabble.com/Is-nested-loops-possible-tp1029366p1029366.html
Sent from the Drools - User mailing list archive at Nabble.com.
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