[rules-users] Working with dates in rules

[Anstis, Michael (M.)]

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 at lists.jboss.org
[mailto:rules-users-bounces at 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 at 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 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") 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 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"
				  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 at 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 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
				
				
				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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