Can't initialise Dialogflow Fulfillment WebhookClient in AWS Lambda

Question

According to the DialogFLow Fulfillment docs, the WebhookClient constructor needs Express HTTP request and response objects. However, in Lambda function, I receive only the event (the request). How do I create the Express request and response objects?

I have tried this so far:

const {WebhookClient} = require('dialogflow-fulfillment');

exports.dialogflowFulfillment = async (event) => {
  let response = {};
  const agent = new WebhookClient({ event, response });

  function sayNiceThings(agent) {
    agent.add(`Nice to meet you!`);
  }

  let intentMap = new Map();
  intentMap.set('Say Nice Things', sayNiceThings);
  agent.handleRequest(intentMap);
};

Answer 1

Create an NodeJS Express App

Install serverless-http package for adding AWS Lambda bridge

Install dialogflow-fulfillment and actions-on-google npm packages.

  npm init -f
  npm install --save express serverless-http
  npm install dialogflow-fulfillment
  npm install actions-on-google

Create index.js file:

index.js:
=========
const serverless = require('serverless-http');
const bodyParser = require('body-parser');
const express = require('express');

const app = express();
app.use(bodyParser.json({ strict: false }));

const {WebhookClient, Card, Suggestion} = require('dialogflow-fulfillment');
const request = require('request');



app.get('/', function (req, res) {

  res.send('Hello World !!!\n');
  console.log("Testing express lambda\n");

})



app.post('/', function (req, res) {


    const agent = new WebhookClient({request: req, response: res});

    function test_handler(agent) {
      agent.add(`Welcome to my agent on AWS Lambda!`);
    }

    // Run the proper function handler based on the matched Dialogflow intent name
    let intentMap = new Map();
    intentMap.set('test-intent', test_handler);

    agent.handleRequest(intentMap);


})


module.exports.handler = serverless(app);

Add configurations in serverless.yml:

serverless.yml
================

service: example-express-lambda

provider:
  name: aws
  runtime: nodejs8.10
  stage: dev
  region: ap-southeast-1

functions:
  app:
    handler: index.handler
    events:
      - http: ANY /
      - http: 'ANY {proxy+}'

Then deploy the lambda function. Add the endpoint url in the Dialogflow fulfilment webhook url.

Reference: https://serverless.com/blog/serverless-express-rest-api/