How does the formActions works? - rasa-nlu

Question

I do not understand how the slot mapping does to know which "utterance" to answer the user to get the "entity" requested.
example of my form class:
class RestaurantForm(FormAction):
"""Example of a custom form action"""
def name(self):
# type: () -> Text
"""Unique identifier of the form"""
return "formaejemplo"
#staticmethod
def required_slots(tracker):
# type: () -> List[Text]
"""A list of required slots that the form has to fill"""
return ["valor1","valor2","valor3"]
def slot_mappings(self):
return {"valor1": self.from_entity(entity="valor1",intent="getvalor1"),
"valor2": self.from_entity(entity="valor2",intent="getvalor2"),
"valor3": self.from_entity(entity="valor3",intent="getvalor3")}
def submit(self, dispatcher, tracker, domain):
dispatcher.utter_template('utter_listo', tracker)
return []
domain.yml:
intents:
- peticion_habitacion:
use_entities: false
- getvalor1
- getvalor2
- getvalor3
entities:
- valor1
- valor2
- valor3
slots:
valor1:
type: unfeaturized
auto_fill: false
valor2:
type: unfeaturized
auto_fill: false
valor3:
type: unfeaturized
auto_fill: false
actions:
- utter_prueba
- utter_completo
templates:
utter_completo:
- text: "listo:\nvalor 1 {valor1} \nvalor 2 {valor2} \nvalor 3 {valor3}"
utter_prueba:
- text: "iniciando prueba:\n"
utter_valor1:
- text: "dame el valor 1 no enteros"
utter_valor2:
- text: "dame el valor 2 no enteros"
utter_valor3:
- text: "dame el valor 3 no enteros"
utter_listo:
- text: "prueba completa"
forms:
- formaejemplo
in the section where you get the value1, value2 etc ... it is according to the Rasa documentation: "valor1": self.from_entity (entity = "valor1", intent = "getvalor1" "the "valor 1" will be obtained from the intent getvalor1."
my question is, at what time or in what part or what file, the action form is told that it will have to send the "utterance" "utter_valor1" or "utter_valor2", because to several Internet examples plus the same examples of bots of rasa, I see that these send the utterance and then recover the value, but I can not get to understand how they send the utterance and then get the value

Answer 1

I assume you mean how the action sdk determines which template it should use to ask for a requested slot, right?
This logic is actually hardcoded here: https://github.com/RasaHQ/rasa_core_sdk/blob/cfffaac0013606f7614ab0f213bc39623ee8b53c/rasa_core_sdk/forms.py#L374
What it does is simply dispatches an utterance which is utter_ask_{the name of slot which should be requested}.
If the user then sends back his answer, the form action is triggered again and the slot value can be extracted.