Jumping over to another intent by using the 'agent.setFollowupEvent(targetIntentEventName)' method in the DialogFlow Messenger fulfillment

Question

I'm trying to find a solution to launch another DialogFlow Intent (via its event) from a webhook (node.js) server after collecting users email address and checking their registration status by making a POST API call to a remote organization server.

Here's a basic schema:

User: Hello!
Chatbot: Hello, I'm an assistance bot. Can I have your email address to verify your registration status, please?
User: [email protected]
Chatbot: Thank you, let me check your status ...
---> Fulfilment code makes a POST API call and gets users status back from a server if there's a match.

Here based on the users status I want to launch a new intent: either Registered_Users_Intent or New_Users_Intent. I tried to use the agent.setFollowupEvent(({ "name": "targetIntentEventName" }) method, but it doesn't trigger a desired event[intent] all the time. I'm not sure how to set it up properly in the fulfilment code to make it work all the time.

Would anyone have any suggestions or reference materials to make this set-up work, please?

Answer 1

When you make a webhook fulfillment request, your API should respond with a JSON response that Dialogflow understands. Instead of calling dialogflow APIs to trigger an event from within your webhook API, the JSON response of the API can contain the name of the event to be triggered next and Dialogflow will do the rest.

Here's the reference for the fulfillment response to trigger a follow-up event: https://cloud.google.com/dialogflow/es/docs/fulfillment-webhook#event

Also, the most likely reason that your current approach works sometimes and doesn't the others, is because triggering an event using dialogflowv2 APIs AND sending back a JSON response (which probably doesn't have the name of the follow up event mentioned) creates a race condition.

Answer 2

Since you are using the Dialogflow Fulfillment Library, make sure to use the latest version in your package.json file. Also, when using the agent.setFollowupEvent() method, make sure to include an agent.add() method for the response. This response will not be returned but is a requirement to be able to use the agent.setFollowupEvent() method.

Here’s an example:

function nameOfFunction(agent) {
    agent.add(`sample response`);
    agent.setFollowupEvent('event_name');
}

For more information on Dialogflow Fulfillment Library, see here. Note that this library is not maintained.

Otherwise, you may create your own code and host it on your chosen web server. From there, you can invoke events by setting the followupEventInput field of the WebhookResponse. Check here for more information.