You got it.
You won't find this proposal in any pattern books!! ;-)
At least you understood the syntax, so you can now officially consider
yourself not a noob.
________________________________
From: rules-users-bounces(a)lists.jboss.org
[mailto:rules-users-bounces@lists.jboss.org] On Behalf Of David Siefert
Sent: 29 January 2009 12:59
To: Rules Users List
Subject: Re: [rules-users] Working with dates in rules
Ah! Sorry, I believe you were saying Day is a fact that I would
have to create for each likely day.... The collect operation is what
gathers all those (Day) facts into a list that is counted. so the rule
fires if there is more than 0 day facts.
My bad!
Thanks,
David
On Thu, Jan 29, 2009 at 6:53 AM, David Siefert
<siefert.david.mailinglist(a)gmail.com> wrote:
Hey, that was quite clever. Where can I find more about
Day()? I did some research about DateFactory which I can see how dates
get parsed according to the documentation, as well as compared with the
conditional operators (<, >, <=, >=, etc).
Thanks,
David
On Thu, Jan 29, 2009 at 5:57 AM, Anstis, Michael (M.)
<manstis1(a)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") works).
I guess you could look at something like this
(gees, this is going to show how "green" I am with Drools now):-
rule "yuck"
when
DateFactory($today : today )
$c : CreditCard( $expires :
expirationDate )
ArrayList( size >= 0 ) from collect(
Day( date >= $today, date <= $expires ))
then
//Difference between "today" and "expiry
date" is more than zero days
end
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.
Mike
________________________________
From:
rules-users-bounces(a)lists.jboss.org
[mailto:rules-users-bounces@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"
when
$c: CreditCard($expires :
expirationDate)
eval(new
TemporalReasoner(Calendar.getInstance()).lessThan($expires))
then
// do something for when credit card
is still valid
end
Now, I'm still generally a noob with
BRs, so I'm not sure how this will affect performance. Any advice?
Thanks,
David
On Thu, Jan 29, 2009 at 3:50 AM, Anstis,
Michael (M.) <manstis1(a)ford.com> wrote:
Hi,
I wonder whether Drools 5 "Complex Event
Processing Support (Temporal Reasoning)" might be what you're looking
for?
http://blog.athico.com/2008/07/drools-50-m1-new-and-noteworthy.html
With kind regards,
Mike
________________________________
From:
rules-users-bounces(a)lists.jboss.org
[mailto:rules-users-bounces@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
Hi-
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 functionality?
Big thanks,
David
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