RASA - Creating forms

Forms

Forms are useful when an assistant needs to collect information from the user. For example, when a user wants to subscribe to a newsletter, the assistant must ask for their email address.
A form is a specific kind of custom action that contains the logic to loop over a set of required slots and ask the user for this information.

To use forms, you need to make sure that the Rule Policy is added to your policy configuration.

# config.yml
# ... previous content ...
policies:
- name: RulePolicy

The policy configuration is located in config.yml.
If you leave policies empty, the RulePolicy will be added automatically.

We will create a newsletter_form, that will be used to collect an email address from the user and frequency how often to send emails.

# domain.yml
# ... previous content ...
forms:
  newsletter_form:
    email:
      - type: from_text
    frequency:
      - type: from_text

Here we are creating a form named newsletter_form. This name is also the name of the action which we will use in stories to handle form executions.
Then we are saying that slots named email and frequency will be filled from_text.
But what is a slot? Let's learn about slots next.

Slots

Slots are our chatbot's memory. They act as a key-value store which can be used to store information the user provided (e.g their email address) as well as information gathered about the outside world (e.g. the result of a database query).

Slots are defined in the slots section in our domain with their name, type and if and how they should influence the assistant's behavior.
The following example defines slots with name email and frequency, both having type text.

# domain.yml
# ... previous content ...
slots:
  email:
    type: text
    influence_conversation: false
  frequency:
    type: text
    influence_conversation: false

We are also saying that those slots don't influence the conversation with the influence_conversation property.
The way the slot influences the conversation will depend on its slot type. Here, the slot type is text, but there are other types like bool, categorical, float, list, any or you can even create your own slot type.

You can learn more about slot types in the documentation.
You can learn more about slots in the documentation or in my next article.

Creating new intents

We need to create a new intent that will mean that a user wants to subscribe to a newsletter.

# data/nlu.yml
# ... previous content ...
  - intent: subscribe
    examples: |
      - I want to get the newsletter
      - Can you send me the newsletter?
      - Can you sign me up for the newsletter?
      - I want to subscribe to a newsletter.

We also need intents informing the chatbot about our email and how often we would like to receive emails.

# data/nlu.yml
# ... previous content ...
  - intent: inform_email
    examples: |
      - My email is [e-mail]
      - [e-mail]
      - Please send it to [e-mail]
      - Email is [e-mail]

  - intent: inform_frequency
    examples: |
      - every week
      - once a week
      - twice per month
      - as ofter as possible
      - once a month

Don't forget to add these new intents to your domain.yml file

# domain.yml
# ... previous content ...
intents:
  - greet
  - mood_great
  - subscribe
  - inform_email
  - inform_frequency

Responses

Now we need to add three new responses. First one will be chatbot asking about user's email address, second one will ask the frequency and the third one will be chatbot confirming the subscription.

# domain.yml
# ... previous content ...
responses:
  # ... previous responses ...
  utter_ask_email:
    - text: What is your email address?
  utter_ask_frequency:
    - text: How often do you want to receive emails from me?
  utter_subscribed:
    - text: You're all set! Check your inbox at {email} to confirm your subscription.
            You will receive emails {frequency}.

Notice that we are using the value of email and frequency slots in our response by putting the name of the slot in curly brackets.
Naming of utter_ask_email and utter_ask_frequency is important.
Once the form action gets called for the first time, the form gets activated and will prompt the user for the next required slot value. It does this by looking for a response called utter_ask_<form_name>_<slot_name> or utter_ask_<slot_name> if the former isn't found.

You can learn more about this in the documentation.

Stories

Now, in order to connect users' intents with chatbot's responses, we have to write a story.

# data/stories.yml
# ... previous content ...
  - story: greet and subscribe
    steps:
      - intent: greet
      - action: utter_greet
      - intent: subscribe
      - action: newsletter_form
      - active_loop: newsletter_form
      - active_loop: null
      - action: utter_subscribed

First, user and chatbot exchange greetings.
Then, if user expresses the intent subscribe, newsletter_form is run by calling action of the same name: - action: newsletter_form.
The active_loop: newsletter_form step indicates there is currently an active form.

A form will automatically deactivate itself once all required slots are filled (both email and frequency). You can describe your assistant's behavior for the end of a form with a rule or a story (we will learn about rules later on). If you don't add an applicable story or rule, the assistant will automatically listen for the next user message after the form is finished. But since we want to inform the user about the subscription details, we say that after the form is no longer active (- active_loop: null), an action utter_subscribed should follow.

active_loop: null step indicates that no form should be active before the subsequent steps are taken

You can learn more about form events in the documentation.

Now run rasa train && rasa shell and try chatting with the chatbot.

Entities

On the image above you will notice that the chatbot considers the email to be our whole sentece informing him about our email, not just the email address itself.
To fix this, we will create an email entity.
Entities are structured pieces of information inside a user message. You can think of them as of keywords.
For entity extraction to work, we need to annotate those entities in our training data.

# data/nlu.yml
# ... previous content ...
  - intent: inform_email
    examples: |
      - My email is [[e-mail]](email)
      - [[e-mail]](email)
      - Please send it to [[e-mail]](email)
      - Email is [[e-mail]](email)

We put the value of entity inside square brackets and follow it by the entity name in parentheses. The name of the entity is independent of our form slots.

Previously, we defined that slot email will be filled from_text. We will change this to from_entity now.

# domain.yml
# ... previous content ...
forms:
  newsletter_form:
    email:
      - type: from_entity
        entity: email
    frequency:
      - type: from_text

Below type key we specify from which entity the slot should be filled. In our case, it will be filled from entity email.

We also need to add all our entities to the domain.yml file.

# domain.yml
# ... previous content ...
entities:
  - email

You can learn more about entities in the documentation.

Now, when you run rasa train && rasa shell, you can see that the chatbot finds the email in your answer.

You can learn more about forms in the documentation here and here.

In the next chapter, we will look at how we can test our form and replace some of our stories by rules.

Repository for this tutorial:

petr7555 / rasa-dev-tutorial

You can checkout the state of the repository at the end of this tutorial by running:

git clone --branch 03-creating-forms [e-mail]:petr7555/rasa-dev-tutorial.git

Comments

[Lam Quoc Minh Huy]

I followed these steps and got error (is it cause by the new Rasa Version?)

[Petr Janik]

I don't know what version of Rasa you are using, but it's likely not the reason.
You can clone the final code by running git clone --branch 03-creating-forms [e-mail]:petr7555/rasa-dev-tutorial.git and see if you still get the error.