[rules-users] Date arithmetic in when part

[Wolfgang Laun]

Currently (5.2.0, but not <= 5.1.1) you can do:

rule future
when
    Date( $t: time ) from new Date()
    $p: Person( $dob: dob after[0] $t )
then
    System.out.println( $p.getName() + " not born yet." );
end

There are indeed some restrictions w.r.t. the use of temporal operators but
comparing Date/long field to Date/long field is OK.

(@Lisa: You realize that new Date() is somewhat unprecise when used to mean
"today".)

-W

On 29 June 2011 01:04, lhorton <LHorton at abclegal.com> wrote:

> Interesting.  I tried to use this syntax to find out if a date is older
> than
> "now" using this source:
>
> $p2: Person( $dob2: dob before[3d] new Date() )
>
> but I get and exception: org.drools.RuntimeDroolsException: The 'before'
> operator can only be used to compare one event to another, and never to
> compare to literal constraints.
>
> any idea how to compare to "new Date()"?  I had already written a function
> to do this date comparison, but will use the Drools syntax instead if I can
> get this to work.
>
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