Updating code to Promises to comply with 4.0

Hello,

I am a bit new to Promises and I am struggling to update my code for the future version of alexa-app. Here is an intent I would like to update for example. I am currently use alexa-app 3.2.0. Could you share your input to help me on this? Thanks a lot!

app.launch(function(request, response) {
	var accessTokenReceived = request.sessionDetails.accessToken;
	async.waterfall([
		// STEP 1: check the accessToken
		function(callback) {
			if (accessTokenReceived === undefined) {
				callback('no_access_token');
			}else{
				user.getUserFromAccessTokenPromise(accessTokenReceived).then(function(user) {
					callback(null,user);
				}, function(err){
					var obj = {};
					callback("not_good_access_token");
				});
			}
		},
		//STEP 2 : check stuff
		function(user,  callback) {
			stuff.getStuffFromUserPromise(user).then(function(stuff){
				callback(null, stuff, user, userId);
			},function(err){
				callback("no_stuff");
			});
		},
		function(stuff, user, userId, callback) {
			helper.getStaffUserIdPromise(userId).then(function(staff){
				if (numberOfStaff !== 0) {
					response.say(config.dialog.onLaunchIntent.case13.say);
					response.reprompt(config.dialog.onLaunchIntent.case13.reprompt);
					response.card(config.dialog.onLaunchIntent.case13.cardTitle, config.dialog.onLaunchIntent.case12.card);
					response.shouldEndSession(config.dialog.onLaunchIntent.case13.end);
					response.send();
					callback(null, stuff, user, userId, staff);
				} else {
					callback("no_staff");
				}
			}, function(err){
				callback("error_retrieving_staff");
			});
		},
	], function (err, stuff, user, userId, staff) {
		if(err){
			switch (err) {
				case "no_access_token":
				response.say(config.dialog.onLaunchIntent.case10.say);
				response.reprompt(config.dialog.onLaunchIntent.case10.reprompt);
				response.linkAccount();
				response.shouldEndSession(config.dialog.onLaunchIntent.end);
				response.send();
				break;
				case "not_good_access_token":
				response.say(config.dialog.onLaunchIntent.case10.say);
				response.reprompt(config.dialog.onLaunchIntent.case10.reprompt);
				response.linkAccount();
				response.shouldEndSession(config.dialog.onLaunchIntent.case10.end);
				response.send();
				break;
				case "no_stuff":
				response.say(config.dialog.onLaunchIntent.case11.say);
				response.reprompt(config.dialog.onLaunchIntent.case11.reprompt);
				response.card(config.dialog.onLaunchIntent.case11.cardTitle, config.dialog.onLaunchIntent.case11.card);
				response.shouldEndSession(config.dialog.onLaunchIntent.case11.end);
				response.send();
				break;
				case "no_staff":
				response.say(config.dialog.onLaunchIntent.case12.say);
				response.reprompt(config.dialog.onLaunchIntent.case12.reprompt);
				response.card(config.dialog.onLaunchIntent.case12.cardTitle, config.dialog.onLaunchIntent.case12.card);
				response.shouldEndSession(config.dialog.onLaunchIntent.case12.end);
				response.send();
				break;
				default:
				response.say(config.dialog.onLaunchIntent.case6.say);
				response.reprompt(config.dialog.onLaunchIntent.case6.reprompt);
				response.card(config.dialog.onLaunchIntent.case6.cardTitle, config.dialog.onLaunchIntent.case6.card);
				response.shouldEndSession(config.dialog.onLaunchIntent.case6.end);
				response.send();
			}
		}
	});
	return false;
});

[dblock]

I have a bunch of tests in https://github.com/artsy/elderfield, and some explanation in http://artsy.github.io/blog/2016/11/30/bringing-artsy-to-amazon-echo-alexa/.

Most of our tests look like this:

chai = require('chai');
expect = chai.expect;
chai.use(require('chai-string'));
chai.use(require('chai-http'));

var server = require('../server');

describe('artsy alexa', function() {
    it('tells me about Norman Rockwell', function(done) {
        var aboutIntentRequest = require('./AboutIntentRequest.json');
        chai.request(server)
            .post('/alexa/artsy')
            .send(aboutIntentRequest)
            .end(function(err, res) {
                expect(res.status).to.equal(200);
                var data = JSON.parse(res.text);
                expect(data.response.outputSpeech.type).to.equal('SSML')
                var ssml = data.response.outputSpeech.ssml;
              expect(ssml).to.startWith('<speak>American artist Norman Rockwell ');
              done();
            });
    });
});

[ajcrites]

I think that you may want to stick with using 3.2 as updating your current style will be quite a bit of refactoring. There are some issues in your code (probably just a result of copy/pasting) so this won’t work out of the box, but it is a close analog. The point of promises is to try to keep things to a single chain.

Ideally you would only need one catch and you could derive the actual error from the caught value, i.e. the error you get from getUserFromAccessTokenPromise or getStuffFromUserPromise would be different and you could look at that value in the error in the final catch rather than catching each individual error returned by that promise and then throwing a separate error. If these errors exist throughout your app, consider using app.error to handle them as well as it is also part of the app’s promise chain.

Note that using response.send() is not needed since it gets called automatically when the promise chain resolves.

Example that should work with your existing code: https://gist.github.com/ajcrites/3dbb77998f33ef9f0700bd4f5f748b07

Ideal example (your promise functions throw corresponding error messages): https://gist.github.com/ajcrites/323dc219b588ca7f76c24afe95d03078