Re: [rules-users] using forall to validate same field value from a list

You have to establish the age of one applicant as bound to a variable so that you can ascertain this being equal to the age of all Applicants. rule "age-2" when $list : List( size > 0 ) # ensure non-empty so that get(0) doesn't NPE forall( Applicant( $age : age == ( ((Applicant)$list.get(0)).getAge() ) ) from $list ) then System.out.println( "success" ); end On 15 September 2010 09:52, tushmish <Tushar.Mishra(a)lntinfotech.com&gt; wrote: It's noteworthy that this rule would fire if you insert all Applicant objects that are in the List as 1st order facts. What is does is forall( $app | $app in List & forall ( $f | $f in WM & $f instanceof Applicant & $f == $app & $f.age == $app.age ) ) where the inner "forall" is implied by the general fact matching algorithm. The last term of the inner conjunction is redundant as we have established the identity by $f == $app - the pattern just matches all list elements with themselves. -W