Rasa 2.8 SLOT Validation

In my custom action, I am doing a database query based on the entities or slot values, tracker.get_slot() function. Now I want to make sure that if the slot is wrongly filled, the slot should be reset to none and the rest of the action should execute the same as if that slot was never filled. How do i do that

Call SlotSet with a value of None. Here’s an example use where an array of events is set and returned including a SlotSet event.

I am using the slot outside of the context of form. Lets say that my action_x is predicted. I am running a database query based on three slot values a,b,c. lets say my c slot is unfilled. my custom action will utter a response (call it y) based on the value of a and b. but if my a,b,c slot values are filled. it will do a query and utter a response (call it z) . now when my slot c is wrongly filled, it is doing a query to fetch response z but because c slot is wrongly filled, my z response is not being fetched from db and hence not uttered. So what I now want that if the c slot is not properly filled, it is set to none and i will get the response y uttered from custom action x. remember response y is the response that I am supposed to get when only a and b are filled and c is empty. i hope you understand

It’s the same in a custom action or a form.

class FetchUserCards(Action):

    def name(self) -> str:
        return "fetch_user_cards"

    def run(self, dispatcher: CollectingDispatcher,
            tracker: Tracker, domain: Dict[str, Any]):
        return [SlotSet("return_value", 1)]