What is correct way to respond from webhook running nodejs?

Question

Trying to implement web-hook (with V2 dialogflow) running nodejs. Received response "MalformedResponse 'final_response' must be set.". Below is the code. To the end of POST (app.post) code block was expecting conv.close would send SimpleResponse. But that's not happening. Need help understand why this error is seen and probable direction to solve it.

Thanks

const express = require('express');
const {
  dialogflow,
  Image,
  SimpleResponse,
} = require('actions-on-google')

const bodyParser = require('body-parser');
const request = require('request');
const https = require("https");
const app = express();
const Map = require('es6-map');

// Pretty JSON output for logs
const prettyjson = require('prettyjson');
const toSentence = require('underscore.string/toSentence');

app.use(bodyParser.json({type: 'application/json'}));

// http://expressjs.com/en/starter/static-files.html
app.use(express.static('public'));

// http://expressjs.com/en/starter/basic-routing.html
app.get("/", function (request, response) {
  console.log("Received GET request..!!");
  //response.sendFile(__dirname + '/views/index.html');
  response.end("Response from my server..!!");
});

// Handle webhook requests
app.post('/', function(req, res, next) {
  console.log("Received POST request..!!");
  // Log the request headers and body, to aide in debugging. You'll be able to view the
  // webhook requests coming from API.AI by clicking the Logs button the sidebar.
  console.log('======Req HEADERS================================================');    
  logObject('Request headers: ', req.headers);
  console.log('======Req BODY================================================');    
  logObject('Request body: ', req.body);
  console.log('======Req END================================================');    

  // Instantiate a new API.AI assistant object.
  const assistant = dialogflow({request: req, response: res});

  // Declare constants for your action and parameter names
  //const PRICE_ACTION = 'price';  // The action name from the API.AI intent
  const PRICE_ACTION = 'revenue';  // The action name from the API.AI intent
  var price = 0.0

  // Create functions to handle intents here
  function getPrice(assistant) {
    console.log('** Handling action: ' + PRICE_ACTION);
    let requestURL = 'https://blockchain.info/q/24hrprice';
    request(requestURL, function(error, response) {
      if(error) {
        console.log("got an error: " + error);
        next(error);
      } else {        
        price = response.body;
        logObject('the current bitcoin price: ' , price);
        // Respond to the user with the current temperature.
        //assistant.tell("The demo price is " + price);
      }
    });
  }

  getPrice(assistant); 

  var reponseText = 'The demo price is ' + price;

  // Leave conversation with SimpleResponse 
  assistant.intent(PRICE_ACTION, conv => {
    conv.close(new SimpleResponse({
     speech: responseText,
     displayText: responseText,
    })); 
  });

}); //End of app.post

// Handle errors.
app.use(function (err, req, res, next) {
  console.error(err.stack);
  res.status(500).send('Oppss... could not check the price');
})

// Pretty print objects for logging.
function logObject(message, object, options) {
  console.log(message);
  console.log(prettyjson.render(object, options));
}

// Listen for requests.
let server = app.listen(process.env.PORT || 3000, function () {
  console.log('Your app is listening on ' + JSON.stringify(server.address()));
});

Prisoner · Accepted Answer

In general, The "final_response" must be set error is because you didn't send anything back. You have a lot going on in your code, and while you're on the right track, there are a few things in the code that could be causing this error.

First - in the code, it looks like you are confused about how to send a response. You have both a call to conv.close() and the commented out assistant.tell(). The conv.close() or conv.ask() methods are the way to send a reply using this version of the library. The tell() method was used by a previous version and is no longer supported.

Next, your code looks like it is only setting up the assistant object when the routing function is called. While this can be done, it is not the usual way to do it. Typically you'll create the assistant object and setup the Intent handlers (using assistant.intent()) as part of the program initialization. This is a rough equivalent to setting up the express app and the routes for it before the request itself comes in.

The portion that sets up the Assistant and then hooks it into a route might look something like this:

const assistant = dialogflow();
app.post('/', assistant);

If you really wanted to examine the request and response objects first, you might do this as something like

const assistant = dialogflow();
app.post('/', function( req, res ){
  console.log(JSON.stringify(req.body,null,1));
  assistant( req, res );
});

Related to this appears to be that you're trying to execute code in the route handler and then trying to call the intent handler. Again, this might be possible, but isn't the suggested way to use the library. (And I haven't tried to debug your code to see if there are problems in how you're doing it to see if you're doing it validly.) More typical would be to call getPrice() from inside the Intent handler instead of trying to call it from inside the route handler.

But this leads to another problem. The getPrice() function calls request(), which is an asynchronous call. Async calls are one of the biggest problems that causes an empty response. If you are using an async call, you must return a Promise. The easiest way to use a Promise with request() is to use the request-promise-native package instead.

So that block of code might look something (very roughly) like this:

const rp = require('request-promise-native');

function getPrice(){
  return rp.get(url)
    .then( body => {
      // In this case, the body is the value we want, so we'll just return it.
      // But normally we have to get some part of the body returned
      return body;
    });
}

assistant.intent(PRICE_ACTION, conv => {
  return getPrice()
    .then( price => {
      let msg = `The price is ${price}`;
      conv.close( new SimpleResponse({
        speech: msg,
        displayText: msg
      });
    });
});

The important thing to note about both getPrice() and the intent handler are that they both return a Promise.

Finally, there are some odd aspects in your code. Lines such as res.status(500).send('Oppss... could not check the price'); probably won't do what you think they will do. It won't, for example, send a message to be spoken. Instead, the Assistant will just close the connection and say that something went wrong.

What is correct way to respond from webhook running nodejs?

Answers (2)

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