[rules-users] Working with dates in rules
michalbali at gmail.com
Thu Jan 29 07:15:52 EST 2009
I can highly recommend joda-time library (http://joda-time.sourceforge.net/)
I'd insert current date as a fact.
I haven't tried this but you might be able to do:
SomeFact( date == (current.plusDays(3)) )
On Thu, Jan 29, 2009 at 11:57 AM, Anstis, Michael (M.) <manstis1 at ford.com>wrote:
> Hi David,
> Sorry it was of little help.
> A rule of thumb is to stay away from "eval" as it kills performance (the
> patterns can't be indexed).
> I'm not sure if Drools can handle Date variables (the docs state it handles
> Data literals formatted as "dd-mmm-yyyy" so Cheese( date == "27-Oct-2008")
> I guess you could look at something like this (gees, this is going to show
> how "green" I am with Drools now):-
> rule "yuck"
> DateFactory($today : today )
> $c : CreditCard( $expires : expirationDate )
> ArrayList( size >= 0 ) from collect( Day( date >= $today, date <=
> $expires ))
> //Difference between "today" and "expiry date" is more than zero
> This does require the insertion of (possibly) huge amounts of Day facts.
> Yuck. There must be a better way (in fact your eval looks soooo much
> cleaner). I'm just throwing out ideas.
> Good luck with your adventures with Drools.
> *From:* rules-users-bounces at lists.jboss.org [mailto:
> rules-users-bounces at lists.jboss.org] *On Behalf Of *David Siefert
> *Sent:* 29 January 2009 11:31
> *To:* Rules Users List
> *Subject:* Re: [rules-users] Working with dates in rules
> Not sure--Drools 5 temporal reasoning looks like it would be the answer.
> Only problem is that I need a solution now, so I am stuck with Drools 4.
> This did give me some ideas though. I created myself a class called
> TemporalReasoner. This has a few methods, namely to roll a date (so I can
> tell it x amount of time from now), and then compare it to another date.
> So in my rule, lets say I have a fact CreditCard with property
> expiration:Date (speaking uml-ishly for "a property named 'expiration' of
> type Date"):
> rule "Fires when expiration less than today"
> $c: CreditCard($expires : expirationDate)
> eval(new TemporalReasoner(Calendar.getInstance()).lessThan($expires))
> // do something for when credit card is still valid
> Now, I'm still generally a noob with BRs, so I'm not sure how this will
> affect performance. Any advice?
> On Thu, Jan 29, 2009 at 3:50 AM, Anstis, Michael (M.) <manstis1 at ford.com>wrote:
>> I wonder whether Drools 5 "Complex Event Processing Support (Temporal
>> Reasoning)" might be what you're looking for?
>> With kind regards,
>> *From:* rules-users-bounces at lists.jboss.org [mailto:
>> rules-users-bounces at lists.jboss.org] *On Behalf Of *David Siefert
>> *Sent:* 29 January 2009 09:40
>> *To:* Rules Users List
>> *Subject:* [rules-users] Working with dates in rules
>> I'm wondering how it would be possible to compare a part of a date in the
>> lhs condition of a rule in a Drool. In other words, I need to compare a
>> date to see if it is *x* days from the current date, *n* hours from
>> current time, etc. Would anyone be kind enough to provide an example? I'm
>> thinking I may have to implement something of my own to offer that
>> Big thanks,
>> rules-users mailing list
>> rules-users at lists.jboss.org
> rules-users mailing list
> rules-users at lists.jboss.org
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