Dispatcher

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A dispatcher is an instance of the CollectingDispatcher class used to generate responses to send back to the user.

CollectingDispatcher #

CollectingDispatcher has one method, utter_message, and one attribute, messages. It is used in an action's run method to add responses to the payload returned to the Rasa server. The Rasa server will in turn add BotUttered events to the tracker for each response. Responses added using the dispatcher should therefore not be returned explicitly as events. For example, the following custom action returns no events explicitly but will return the response, "Hi, User!" to the user:

class ActionGreetUser(Action):

def name(self) -> Text:
        return "action_greet_user"

async def run(
        self,
        dispatcher: CollectingDispatcher,
        tracker: Tracker,
        domain: Dict[Text, Any],
    ) -> List[EventType]:
        dispatcher.utter_message(text="Hi, User!")
        return []

CollectingDispatcher.utter_message #

The utter_message method can be used to return any type of response to the user.

Parameters #

The utter_message method takes the following optional arguments. Passing no arguments will result in an empty message being returned to the user. Passing multiple arguments will result in a rich response (e.g. text and buttons) being returned to the user.

• text: The text to return to the user.

dispatcher.utter_message(text="Hey there")

• image: An image URL or file path that will be used to display an image to the user.

dispatcher.utter_message(image="https://i.imgur.com/nGF1K8f.jpg")

• json_message: A custom json payload as a dictionary. It can be used to send channel specific responses. The following example would return a date picker in Slack:

date_picker = {
    "blocks": [
        {
            "type": "section",
            "text": {
                "text": "Make a bet on when the world will end:",
                "type": "mrkdwn"
            },
            "accessory": {
                "type": "datepicker",
                "initial_date": "2019-05-21",
                "placeholder": {
                    "type": "plain_text",
                    "text": "Select a date"
                }
            }
        }
    ]
}

dispatcher.utter_message(json_message=date_picker)

• response: The name of a response to return to the user. This response should be specified in your assistant's domain.

dispatcher.utter_message(response="utter_greet")

• attachment: A URL or file path of an attachment to return to the user.

dispatcher.utter_message(attachment="")

• buttons: A list of buttons to return to the user. Each button is a dictionary and should have a title and a payload key. A button can include other keys, but these will only be used if a specific channel looks for them. The button's payload will be sent as a user message if the user clicks the button.

dispatcher.utter_message(buttons=[
    {"payload": "/affirm", "title": "Yes"},
    {"payload": "/deny", "title": "No"},
])

• elements: These are specific to using Facebook as a messaging channel. For details of expected format see Facebook's documentation

• **kwargs: arbitrary keyword arguments, which can be used to specify values for variable interpolation in response variations. For example, given the following response:

responses:
  utter_greet_name:
    - text: Hi {name}!

You could specify the name with:

dispatcher.utter_message(response="utter_greet_name", name="Aimee")

Return type #

None