Instead of defining fallback actions via custom action, you can use rules as well. If interested in rule-based approach below is the process:- Create out_of_scope intent in nlu and give some examples which are completely different from your use case and then define utter_out_of_scope reply in domain. Now simply just add a rule for handling out of scope questions:-
-
rule: out-of-scope
steps:
- intent: nlu_fallback
- action: utter_out_of_scope