dialogflow-fulfillment-library and express, what to res on? - node.js

Question

I'm trying to use the dialog-fulfillment-library with express, without firebase functions. I'm having trouble finding how to res on the agent though.
const { WebhookClient, Card, Suggestion } = require('dialogflow-fulfillment');
module.exports = function () {
let self = {};
self.create = function (req, res, next) {
const agent = new WebhookClient({request: req, response: res});
agent.add(new Suggestion(`Quick Reply`));
agent.add(new Card({
title: `Title: this is a card title`,
imageUrl: 'https://developers.google.com/actions/images/badges/XPM_BADGING_GoogleAssistant_VER.png',
text: `This is the body text of a card. You can even use line\n breaks and emoji! 💁`,
buttonText: 'This is a button',
buttonUrl: 'https://assistant.google.com/'
})
);
res.json(agent);
};
return self;
};
I get a TypeError: Converting circular structure to JSON
I've tried decycling the agent but then it doesn't work on the dialogflow side.
using:
res.send(JSON.stringify(agent, decycle()));
returns: Webhook call failed. Error: Failed to parse webhook JSON response: Cannot find field: request_ in message google.cloud.dialogflow.v2.WebhookResponse.
Has anyone used it in this way or is it not possible?

Answer 1

I have submitted a Pull Request for the same.
Following code works for me.
package.json
{
"name": "Test_Agent",
"version": "0.0.1",
"description": "Test Agent webhook",
"main": "server.js",
"author": "Abhinav Tyagi, New Delhi, India",
"dependencies": {
"dialogflow-fulfillment": "^0.4.1",
"body-parser": "^1.18.3",
"express": "^4.16.3",
"actions-on-google": "^2.2.0"
}
}
server.js
'use strict';
const {WebhookClient} = require('dialogflow-fulfillment');
const express = require('express');
const bodyParser = require('body-parser');
const app = express();
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({extended: true}));
function welcome (agent) {
agent.add(`Welcome to Express.JS webhook!`);
}
function fallback (agent) {
agent.add(`I didn't understand`);
agent.add(`I'm sorry, can you try again?`);
}
function WebhookProcessing(req, res) {
const agent = new WebhookClient({request: req, response: res});
console.info(`agent set`);
let intentMap = new Map();
intentMap.set('Default Welcome Intent', welcome);
intentMap.set('Default Fallback Intent', fallback);
// intentMap.set('<INTENT_NAME_HERE>', yourFunctionHandler);
agent.handleRequest(intentMap);
res.status(200).send(agent);
}
// Webhook
app.post('/', function (req, res) {
console.info(`\n\n>>>>>>> S E R V E R H I T <<<<<<<`);
WebhookProcessing(req, res);
});
app.listen(8080, function () {
console.info(`Webhook listening on port 8080!`)
});
Make sure to use both action-on-google and dialogflow-fulfillment modules.
The intentMap keys is the intent.displayName.