dialogflow agent not ouputting text from inside HTTP request callback

Question

I'm trying to get data from an external site triggered by the welcome intent. Right now I'm trying a simple GET request to google.com.

The agent works as expected except when called from insided the request callback. It sometimes works and sometimes desn't.

'use strict';    
const functions = require('firebase-functions');
const {WebhookClient} = require('dialogflow-fulfillment');
const {Card, Suggestion} = require('dialogflow-fulfillment');
process.env.DEBUG = 'dialogflow:debug'; 

exports.dialogflowFirebaseFulfillment = functions.https.onRequest((request, response) => {
  const agent = new WebhookClient({ request, response });

  function search(agent){

          var request = require("request");
          var options = {
            method: 'GET',
            url: 'http://google.com'
          };

          console.log("Before request");
          agent.add("Before request");

          request(options, function (error, response, body){
            console.log("Request completed");
            agent.add("Request completed");     //<- This line doesn't show in agent
            console.log("finished");            //<- This line shows in the log
          });

          console.log("Request sent");
          agent.add(`Request sent`);
  }

  let intentMap = new Map();
  intentMap.set('Default Welcome Intent', search);
  agent.handleRequest(intentMap);
});

I have noticed in the log the message "Function execution took 1697 ms, finished with status code: 200" shows before the message "finished". I don't know if that means that process is closing and ignoring the agent.add() calls after that point.

Image: firebase log console showing function excecution finished before request compelted

Answer 1

The issue is with the callback/promise. You need to return a promise inside your search function.

function search(agent, query){
    return new Promise((resolve, reject) => {
      request.get(options, (error, response, body) => {
      .....
      agent.add(...)
      resolve();
     });
   });
};

The original answer can be found in the following Github issue:

https://github.com/dialogflow/dialogflow-fulfillment-nodejs/issues/3

EDIT:

Got a little help from the DialogFlow support staff. I little varation was missing to the proposed code to work properly:

function search(agent, query){
  return new Promise((resolve, reject) => {
    request.get(options, (error, response, body) => {
      .....
      let output = agent.add(...)
      resolve(output);  //<- agent.add() should be passed as argument in resolve()
    });
  });
};