Fill a slot with either one two entities

Rasa Open Source
1

Hello forum!

I have a simple form that provides the user with vaccination statistics by location. We have per-country data, and we are planning to add per-city data too. E.g.

User: What percentage of the population is vaccinated in Italy?
Bot: As of today, 78% have received one shot and 77% both shots.
User: Thats great, thanks!

For countrywide results, we had a very simple form:

(domain.yml)
vaccine_stats_form:
    location:
    - type: from_entity
      entity: country

But now, we want to enable user declaring either a country or a city. Ideally, we would want something like this

vaccine_stats_form:
    location:
    - type: from_entity
      entity: country OR city

Is there something else we can do? Or do we have to unify the two entities into one umbrella entity (i.e. location)?

2

Hello!

You can do that, but you can also write a custom validation action.

You can use Custom Actions inside Forms. They’re called FormValidationAction. Instead of run(), it has:

  • extract_slotname(): Write logic to extract the slot from the user’s message and return a dictionary of slot names and their values.
  • validate_slotname(): Write logic to check if the slot slotname is valid and return a dictionary of slot names and their values.
  • required_slots(): Write logic to decide which slots should be asked about and return a list of slot names.

Please see: Forms: Advanced Usage.

In your case, it’s the extract method that you want to modify. You check if the message has a city entity. If yes, you fill it in the location slot; if not, you try the same with the country entity:

class ValidateRestaurantForm(FormValidationAction):
    def name(self):
        return 'validate_vaccine_stats_form'

    async def required_slots(self, slots_from_domain, dispatcher, tracker, domain):
        return slots_from_domain

    async def extract_location(self, dispatcher, tracker, domain):
        city    = next(tracker.get_latest_entity_values('city'),    None)
        country = next(tracker.get_latest_entity_values('country'), None)
        
        location = city if city else country

        return {'location': location}

If you don’t/won’t need to differentiate between cities and countries, I’d suggest going with the simpler approach of merging them into one location entity.

3

Thank you so much for your timely response! We had missed the extract_slot_name feature. We will use it to solve another problem, that of extracting time slots from specific entities of the user, apart from the duckling-extracted ones.

One more question is (and I haven’t found the answer in the docs): what do we do with the required slots declared inside the form declaration (in the domain.yml) ? I think it doesn’t matter anymore, so we can just leave it like before, right?

vaccine_stats_form:
    location:
    - type: from_entity
      entity: country

Thanks a lot,

Kosmas

1 Like
4

That’s right :slight_smile: The action will take priority