Re: [rules-users] Drools & "Query by Example"?
--- On Fri, 9/5/08, Michael Zimmermann <list(a)incunabulum.de> wrote:
rule "MyRule"
when
book(year==myYear, author==myAuthor ...)
then
....
This works only if all properties myYear, myAuthor ... are
present. If one is undefined, the rule does not match.
You could have a function that returns true if the properties match or the property is
null:
boolean matchesOrNull(Object o, Object p) {
return p == null ? true : ( o == null ? true : o.equals(p) );
}
Call it using eval in the conditions.
Maybe if it's useful enough an operator could be added to Drools that does the same
thing. "~=" maybe?
GreG