Re: [rules-users] How to handle priority in a rule
Interesting problem, you want dyanmic prioritisation based upon the
value of a field. We have no declarative sugar for this, but it might
make a nice use case. We could allow someone to specify an expression
that determine a value of priority.
salience = ($price.length);
That would allow for some interesting situations. Its unlikely this will
make 4.0 - but the solution interests me enough that if I get bored, I
might just do it ;)
Until that time I think you'll have to use some combination of a
command/semaphore object and additional rules.
Mark
Maxime wrote:
Hello,
I'm trying to find how to manage priority within a rule. Let me
explain the problem. I'll try to be as clear as possible but bear with
me since I am new to rules.
We have two objects, the Product is the object I'm trying to price and
the object Price is the one that knows all the prices. Both products
and prices have fields amount and length. Product amount is
initialized to 0 and prices are going to determine the product amount
depending on its length.
Let's see an example :
Product : P -> length = 5, amount = 0
Price : P1 -> length = 1, amount = 50
Price : P2 -> length = 3, amount = 100
With this configuration, after asserting the 3 objects to the WM, the
amount field of Product P should have a value of 200 ( 1*100 + 2*50)
because the price with the greatest length should be favored over the
other ones.
Here is the rule I made :
rule "Price Product rule using price length"
when
$s : Product (length > 0)
$price : Price($length: length)
then
$s.setAmount($s.getAmount() + $price.getAmount());
$s.setLength($s.getLength() - $length.intValue());
modify($s);
end
This is obviously wrong because it always takes the first asserted
price object. I don't know how to make a rule which would take the
amount of the price object with the greatest length in priority.
Any help would be very much appreciated.
Cheers,
Max
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