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Drools: why indexOf() does not work in LHS?

Why can't I use indexOf() to look for index of specific object in List in when? Here is the example. Once I comment out list.indexOf($o) > 0, rule executes and index shows correct in then section.

declare Seq
list: List
end

rule "initSeq"
when
    $p: ObjectWrapper (
       ...
    )
    $list: List () from collect (ObjectWrapper (...))
    not initSeq (....)
then
    Seq w = new Seq ();
    w.setList($list);
end

rule "doSeq"
when:
    $o: ObjectWrapper (
       ...
    )
    $rr: Seq (
       ...
       list.indexOf($o) > 0
    )
then:
    DroolsLogger.debug ("index: " + $rr.getList().indexOf($o));
end
Solution

  • I confirm that indexOf() works in LHS. I still do not understand the reason why it is was not working for me before, but now I have working rule with indexOf in LHS.