[rules-users] How to pass global variables to a function called in a condition

[Wolfgang Laun]

Frequently I'm debating with myself whether to leave a little room for
posters to reach some logical conclusion by themselves or to spoon-feed it
all to them. ;-)

-W

2011/8/25 Esteban Aliverti <esteban.aliverti at gmail.com>

> Translation: If the LHS of your rules are going to use globals, make sure
> to set them BEFORE you insert/update/retract any fact. :P
>
> Best Regards,
>
> XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
>
> Esteban Aliverti
> - Developer @ http://www.plugtree.com
> - Blog @ http://ilesteban.wordpress.com
>
>
>
> 2011/8/25 Wolfgang Laun <wolfgang.laun at gmail.com>
>
>> Conditions are evaluated when facts are inserted, modified and deleted.
>> -W
>>
>>
>> 2011/8/25 Matthew Erler <wires8 at yahoo.com>
>>
>>> In Drools 5 I'm passing in two global Date objects and need to find the
>>> difference in days between them.  I've discovered that the function
>>> parameters (fromDate and toDate in my case) are null in the condition when
>>> the function is called, but when the function is called in the consequence
>>> they have values.  I can see that because the output of the following rule
>>> is:
>>> fromDate is null
>>> toDate is null
>>> I'm in dateDiff and the date diff is: 14
>>>
>>> I'm guessing that Drools doesn't make globals t available at the point
>>> that I need them.  Can anyone confirm this and offer a solution?
>>>
>>> Here is the rule file itself:
>>>
>>> import java.util.Date;
>>> import org.joda.time.DateMidnight;
>>> import org.joda.time.Days;
>>>
>>> global java.util.Date fromDate;
>>> global java.util.Date toDate;
>>>
>>>
>>> rule "dateDiff"
>>> dialect "mvel"
>>>      when
>>>           eval(getDaysBetweenStartAndEndDate(fromDate, toDate) < 10)
>>>      then
>>>           System.out.println( "I'm in dateDiff and the date diff is: "
>>> +        getDaysBetweenStartAndEndDate(fromDate, toDate));
>>> end
>>>
>>>
>>> function int getDaysBetweenStartAndEndDate(Date fromDate, Date toDate) {
>>>     if (fromDate==null) System.out.println("fromDate is null");
>>>     if (toDate==null) System.out.println("toDate is null");
>>>   return Days.daysBetween(new DateMidnight(fromDate), new
>>> DateMidnight(toDate)).getDays();
>>> }
>>>
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>>> rules-users at lists.jboss.org
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>>>
>>>
>>
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