Error: Platform can NOT be empty at new Payload in Dialogflow

Question

I have a serverless app where I want to run my logic from the chatbot request coming from Facebook Messenger. When I run the intent function for test_handler I get the correct response back. But after I added another handler for skillRatio I seem to be getting the error in the title i.e

Error: Platform can NOT be empty at new Payload

. My code is as below.

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, Payload, Image, 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!`);
      agent.add(new Image("https://image-charts.com/chart?chs=700x190&chd=t:60,40&cht=p3&chl=Hello%7CWorld&chf=ps0-0,lg,45,ffeb3b,0.2,f44336,1|ps0-1,lg,45,8bc34a,0.2,009688,1"))
    }

    function skillRatio(agent) {
      agent.add(`Let me just have a look and I'll gather the data. *Processing Chart Data....Mmmm Pie*. 
        Here we go! Here is the data on your $Skills.original request.`);
      //agent.add(`Feel free to save or share :)`);
      //agent.add(new Image("https://image-charts.com/chart?chs=700x190&chd=t:60,40&cht=p3&chl=Hello%7CWorld&chf=ps0-0,lg,45,ffeb3b,0.2,f44336,1|ps0-1,lg,45,8bc34a,0.2,009688,1"))
    }

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

    if (agent.requestSource === agent.FACEBOOK) {
      intentMap.set('super-test', test_handler);
      intentMap.set('skill-ratio', skillRatio);
    } else {

    }

    agent.handleRequest(intentMap);
})
module.exports.handler = serverless(app);

Dialogflow Images:

I am trying to run the code on Messenger. Any help would be hugely appreciated as I am so stuck trying to get my head around this.

Answer 1

As it turns out, in the below image, a Custom Payload was causing the issue I was having. If you get the same error

Error: Platform can NOT be empty at new Payload.

Triple check your default responses across all the response types and remove anything that has an empty payload.

Answer 2

Your resolution is a little intuitive and not completely correct. It is not specifically a problem with an empty payload, the problem persists with having a payload in general.

You can try to either set the platform manually like so => How to set a custom platform in Dialogflow NodeJS Client

or choose one of the methods described in here => https://github.com/dialogflow/dialogflow-fulfillment-nodejs/issues/153

Setting the platform befor initializing the WebHookClient

if (!request.body.queryResult.fulfillmentMessages)
    return;
request.body.queryResult.fulfillmentMessages = request.body.queryResult.fulfillmentMessages.map(m => {
    if (!m.platform)
        m.platform = 'PLATFORM_UNSPECIFIED';
    return m;
});