alexa-pure-handlers

🌟🦄 Write pure handlers for the official Node.js Alexa Skills Kit SDK. 🦄🌟

One little flaw I found with the Alexa Skills Kit SDK for Node.js is, that it does encourage you to write handlers that are bound to an specific context and are therefore full of side effects. Side effects are bad, because they make your handlers less predictable and are much harder to test than pure, functional handlers.

Pure handlers are a good thing, because every dependency is provided explicitely through their arguments, and they can have a determined return value, which makes testing a breeze.

Install

npm install --save alexa-pure-handlers

If you're hosting your skill on AWS Lambda, please make sure to set your runtime to Node.js 6.10.

Usage

Step 1: Write your pure intent handlers

// inside handlers.js
const myIntentHandler = ({ attributes, t }) => {

  attributes.foo = 123;
  const emit = [':tell', t('MY_LOCALIZED_MESSAGE')]

  return { attributes, emit };
}

module.exports = { myIntentHandler };

Step 2: Wrap your handlers with pure

const Alexa = require('alexa-sdk');
const pure = require('alexa-pure-handlers');
const { myIntentHandler } = require('./handlers');

exports.handler = (event, context, callback) => {
    const alexa = Alexa.handler(event, context);

    alexa.registerHandlers(handlers);
    alexa.execute();
};

const handlers = {
  'MyIntent': pure(myIntentHandler) // This is where the 🌟🦄 happens
};

Promises Support

Want to use Promises/A+ with your pure handlers? We got you covered there, too!

const myPromiseIntentHandler = ({ attributes, t }) => {
  return fetch('http://api.example.org/unicorns')
    .then(res => {
      attributes.unicorns = res.json();
      
      return {
        attributes,
        emit: [':tell', t('OMG_UNICORNS')]
      };
    })
    .catch(err => {
      return {
        emit: [':tell', t('THE_INTERWEBS_EXPLODED')]
      };
    })
  ;
};

Maintainer

Pascal Cremer

• Email: [email protected]
• Twitter: @b00gizm
• Web: http://codenugget.co

License

The MIT License (MIT)

Copyright (c) 2017 Pascal Cremer

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.