Promise Patterns (and tools) at Mixmax.

async.js

/**
 * Async/Await
 */
const mongoist = require('mongoist');
const db = mongoist('mongodb://user:password@mongo.net');

function getContact(name) {
  return db.contacts.findOne({
    firstName: name
  });
}

const got = require('got');
// Instructions for getting this token are here:
// https://developer.mixmax.com/docs/getting-started-with-the-api
const MIXMAX_API_TOKEN = 'test_token';

async function sendEmail(name, message) {
  const contact = await getContact(name);
  const { email } = contact;
  const message = {
    to: email,
    subject: 'Promises are better.'
    html: message
  }

  const result = await got({
    url: 'https://api.mixmax.com/v1/send',
    method: 'POST',\
    headers: {
      'X-API-TOKEN': MIXMAX_API_TOKEN
    }
    body: JSON.stringify({ message })
  });

  return result;
}

async function sendManyEmails(names, message) {
  try {
    const results = await Promise.all(names.map((name) => {
      return sendEmail(name, message);
    });

    // Handle results.

  } catch (err) {
    // Handle error.
  }
}

callbacks.js

/**
 * Callbacks
 */
const mongojs = require('mongojs');
const db = mongojs('mongodb://user:password@mongo.net');

function getContact(name, cb) {
  db.contacts.findOne({
    firstName: name
  }, (err, res) => {
    if (err) return cb(err);

    cb(null, res);
  });
}

const request = require('request');
// Instructions for getting this token are here:
// https://developer.mixmax.com/docs/getting-started-with-the-api
const MIXMAX_API_TOKEN = 'test_token';

function sendEmail(name, message, cb) {
  getContact(name, (err, result) => {
    if (err) return cb(err);
    const { email } = result;
    const message = {
      to: email,
      subject: 'Callbacks are ok.'
      html: message
    }

    request({
      url: 'https://api.mixmax.com/v1/send',
      method: 'POST',\
      headers: {
        'X-API-TOKEN': MIXMAX_API_TOKEN
      }
      body: JSON.stringify({ message })
    }, (err, result) => {
        cb(err, result);
    });
  });
}

function sendManyEmails(names, message, cb) {
  names.each((name) => {
    sendEmail(name, message, (err, result) => {
      // only one is finished.
    });
  });

  // How do I know when they all finish?
}

promises.js

/**
 * Promises
 */
const mongojs = require('mongojs');
const db = mongojs('mongodb://user:password@mongo.net');

function getContact(name) {
  return new Promise((resolve, reject) =>{
    db.contacts.findOne({
      firstName: name
    }, (err, res) => {
      if (err) return reject(err);

      resolve(res);
    });
  });
}

const request = require('request');
// Instructions for getting this token are here:
// https://developer.mixmax.com/docs/getting-started-with-the-api
const MIXMAX_API_TOKEN = 'test_token';

function sendEmail(name, message) {
  return getContact(name).then((result) => {
    const { email } = result;
    const message = {
      to: email,
      subject: 'Promises are better.'
      html: message
    }

    return new Promise((resolve, reject) => {
      request({
        url: 'https://api.mixmax.com/v1/send',
        method: 'POST',\
        headers: {
          'X-API-TOKEN': MIXMAX_API_TOKEN
        }
        body: JSON.stringify({ message })
      }, (err, result) => {
        if (err) return reject(err);

        resolve(result);
      });
    });
  }).then((result) => {
    return Promise.resolve(result);
  });
}

function sendManyEmails(names, message) {
  Promise.all(names.map((name) => {
    return sendEmail(name, message);
  }).then((results) => {
    //Handle the array.
  }).catch((err) => {
    // Handle the error.
  })
}

tools.js

/**
 * Using promise-callbacks
 * More at: github.com/mixmaxhq/promise-callbacks
 */

const { deferred } = require('promise-callbacks');

function getContact(name) {
  const promise = deferred();

  db.contacts.findOne({
    firstName: name
  }, promise.defer());

  return promise;
}

/**
 * Using promise-pool
 * More at: github.com/mixmaxhq/promise-pool
 */

const PromisePool = require('promise-pool');

async function bulkSendEmails(names) {
  const pool = new PromisePool(10);

  names.each((name) => {
    await pool.start(async () => {
      sendEmail(name, 'Hello!');
    });
  });

  await pool.flush();

  return { message: 'success' };
}


/**
 * Using promise-iterate
 * More at: github.com/mixmaxhq/promise-iterate
 */

const { promiseIterate } = require('promise-iterate');
const mongoist = require('mongoist');
const db = mongoist('mongodb://user:password@mongo.net');

async function sendToEveryone(names) {
  const cursor = db.contacts.findAsCursor({});

  await promiseIterate(cursor, async (contact) => {
    await sendEmail(contact.firstName, 'Hello!');
  });

  return { message: 'success' };
}