Dialogflow+外部API+Google Cloud Functions*没有*Firebase：如何返回履行响应？

'use strict';

const rpn = require('request-promise-native'); 
const http = require('http');
const hostAPI = 'my host API URL goes here';
const url = require('url');
const {WebhookClient} = require('dialogflow-fulfillment');

exports.myGoogleCloudSearch = (req, res) => {
  	const agent = new WebhookClient({request: req, response: res}); // Dialogflow agent
	// These are logged in Google Cloud Functions
	console.log('Dialogflow Request headers: ' + JSON.stringify(req.headers));
  	console.log('Dialogflow Request body: ' + JSON.stringify(req.body));
  
  	// Default welcome intent, this comes through to Dialogflow
  	function welcome(agent) {
    	agent.add('This welcome message comes from Google Cloud Functions.');
    }

  	// Default fallback intent, this also comes through
  	function fallback(agent) {
    	agent.add('This is the fallback response from Google Cloud Functions.');
    }
		
 	function searchMyInfo(agent) {
    	// get parameters given by user in Dialogflow
      	const param1 = agent.parameters.param1;
      	const param2 = agent.parameters.param2;
      	const param3 = agent.parameters.param3
		// this is logged
      	console.log('Parameters fetched from Dialogflow: ' + param1 + ', ' + param2 + ', ' + param3);
      	
       	var myUrl = hostAPI + param1 + param2 + param3;
		// the URL is correct and also logged
       	console.log('The URL is ' + myUrl);
		
		// Everything up to here has happened between Dialogflow and Google Cloud Functions
		// and inside GCF, and up to here it works
		
		// Next, contact the host API to get the requested information via myUrl
		// Using this as an example but *without* Firebase:
		// https://github.com/dialogflow/fulfillment-weather-nodejs/blob/master/functions/index.js#L41
		
		function getMyInfo(param1, param2, param3) {
			console.log('Inside getMyInfo before Promise'); // this is logged
			return new Promise((resolve, reject) => {
				console.log('Inside getMyInfo after Promise'); // this is logged
				console.log('Should get JSON from ' + myUrl);
				rpn.get(myUrl, (res) => {
					// The code is run at least up to here, since this is logged:
					console.log('Inside rpn.get');
					
					// But then the Google Cloud log just says 
					// "Ignoring exception from a finished function"
					// and nothing below is logged (or run?)
					
					let body = ''; // variable to store response chunks
					res.on('data', (chunk) => {body += chunk;}); // store each response chunk
					res.on('end', () => {
						// this is not logged, so something must go wrong here
						console.log('Inside res.on end block');
						
						// Parse the JSON for desired data
						var myArray = JSON.parse(body); // fetched JSON parsed into array
						console.log(myArray); // not logged
						
						// Here I have more parsing and filtering of the fetched JSON
						// to obtain my desired data. This JS works fine for my host API and returns
						// the correct data if I just run it in a separate html file,
						// so I've left it out of this example because the problem seems
						// to be with the Promise(?).
						
						// Create the output from the parsed data
						// to be passed on to the Dialogflow agent

						let output = agent.add('Parsed data goes here');
						console.log(output);
						resolve(output); // resolve the promise
					}); // res.on end block end
					
					// In case of error
					res.on('error', (error) => {
						// this is not logged either
						console.log('Error calling the host API');
						reject();
					}); // res.on error end
				}); // rpn.get end 
			}); // Promise end
		} // getMyInfo end
		
		// call the host API: this does not seem to work since nothing is logged
		// and no error message is returned

		getMyInfo(param1, param2, param3).then((output) => {
			console.log('getMyInfo call started');
			// Return the results of the getMyInfo function to Dialogflow
			res.json({'fulfillmentText': output});
		}).catch(() => {
			// no error message is given either
			res.json({'fulfillmentText' : 'There was an error in getting the information'});
			console.log('getMyInfo call failed');
		});
		
    } // searchMyInfo(agent) end
  
  	// Mapping functions to Dialogflow intents
  	let intentMap = new Map();
  	intentMap.set('Default Welcome Intent', welcome); // this works
  	intentMap.set('Default Fallback Intent', fallback); // this works
  	intentMap.set('my.search', searchMyInfo); // this does not work
  	agent.handleRequest(intentMap);

}; // exports end