Forms

These docs are for version 1.x of Rasa Open Source.

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• Tutorial: Rasa Basics
• Tutorial: Building Assistants
• Command Line Interface
• Architecture
• Messaging and Voice Channels
• Testing Your Assistant
• Setting up CI/CD
• Validate Data
• Configuring the HTTP API
• Deploying Your Rasa Assistant
• Cloud Storage

Forms

One of the most common conversation patterns is to collect a few pieces of information from a user in order to do something (book a restaurant, call an API, search a database, etc.). This is also called slot filling.

If you need to collect multiple pieces of information in a row, we recommended that you create a FormAction. This is a single action which contains the logic to loop over the required slots and ask the user for this information.

When you define a form, you need to add it to your domain file. If your form’s name is restaurant_form, your domain would look like this:

forms:
  - restaurant_form
actions:
  ...

To use forms, you also need to include the FormPolicy in your policy configuration file. For example:

policies:
  - name: "FormPolicy"

Using a FormAction, you can describe all of the happy paths with a single story. By “happy path”, we mean that whenever you ask a user for some information, they respond with the information you asked for.

## happy path
* request_restaurant
    - restaurant_form
    - form{"name": "restaurant_form"}
    - form{"name": null}

In this story, the user intent is request_restaurant, which is followed by the form action restaurant_form. With form{"name": "restaurant_form"} the form is activated and with form{"name": null} the form is deactivated again.

The FormAction will only request slots which haven’t already been set. If a user starts the conversation with I’d like a vegetarian Chinese restaurant for 8 people, then they won’t be asked about the cuisine and num_people slots.

Configuration File

To use forms, you also need to include the FormPolicy in your policy configuration file.

Form Basics

When you define a form, you need to add it to your domain file. If your form’s name is restaurant_form, your domain would look like this:

forms:
  - restaurant_form
actions:
  ...

In this section, we explore how to configure a form and define its basic structure and setup.

Custom slot mappings

If you do not define slot mappings, slots will be only filled by entities with the same name as the slot that are picked up from the user input. Here’s an example for the restaurant bot:

def slot_mappings(self) -> Dict[Text, Union[Dict, List[Dict]]]:
    return {
        "cuisine": self.from_entity(entity="cuisine", not_intent="chitchat"),
        "num_people": [
            self.from_entity(
                entity="number", intent=["inform", "request_restaurant"]
            ),
        ],
    }

Validating user input

After extracting a slot value from user input, the form will try to validate the value of the slot. To add custom validation, you can write a helper validation function with the name validate_{slot-name}. Here’s an example:

def validate_cuisine(self, value: Text, dispatcher: CollectingDispatcher, tracker: Tracker, domain: Dict[Text, Any]) -> Dict[Text, Any]:
    if value.lower() in self.cuisine_db():
        return {"cuisine": value}
    else:
        dispatcher.utter_message(template="utter_wrong_cuisine")
        return {"cuisine": None}

Handling unhappy paths

Typically, users will ask questions, make chitchat, change their mind, or otherwise stray from the happy path. The way this works with forms is that a form will raise an ActionExecutionRejection if the user didn’t provide the requested information. You need to handle events that might cause ActionExecutionRejection errors in your stories.

Debugging

The first thing to try is to run your bot with the --debug flag, allowing you to see detailed logs of what’s happening during conversation processing.