[rules-users] Using functions to derive values in "accumulate" (LHS)

[Christian Heupel]

Hello, 

 

I am trying to write a rule for my drools engine. It is (as far as i get it
right), almost a total standard rule, however I'm having troubles with it
and was hoping you could point me into the right direction (as i was
surprised to see no similar question, I hope it is not too basic). 

 

To give you an understanding of what i want to do: I want to calculate a
number of costs a person had on a series of trips. For each trip, a function
getCost() calculates the total amount of money spent (such as hotel, bar,
...). If the total amount of money spent is higher then the person's maximum
money, we take action. I am trying to use the accumulate function, but it
seems as if I'm not able to call the getCost() function there. The rule
looks like this: 

----------------- 

rule "Total Costs" 

when 

$person : Person( eval ($person.maxMoney != null ) ) 

 

$totalCost : Number() 

                from accumulate(    $trip : Trip( $cost : $trip.getCost()  )
from $person.getTrips(), 

                                           sum( $cost ) 

                                      ) 

then 

     // take action 

end 

------------------- 

 

I have tried it with and without the $trip-variable (since I thought I might
have to use it to call its function). 

 

The error I get looks like this: 

 

Error INTERNAL_ERROR: Error: unknown:70:54 Unexpected token ')' 

java.lang.Exception: Error: unknown:70:54 Unexpected token ')' 

        at
com.fluidops.coremgmt.ruleengine.PolicyTask.readRule(PolicyTask.java:489) 

        at
com.fluidops.coremgmt.ruleengine.PolicyTask.readRule(PolicyTask.java:419) 

 

I would be very thankful if one of you could help me out here :) 

 

Best regards, 

Christian

 

 

PS:  I already had this question in the drools forum, it was, however not
forwarded to this mailing list, so please forgive me if it is a double post.

 

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