a promise example

myController.js

const mongoose = require('mongoose');
const Store = mongoose.model('Store');
const StoreB = mongoose.model('StoreB');

// Tells package to use es6 promises
mongoose.Promise = global.Promise;

exports.createStore = (req, res) => {
  const store = new Store(req.body);
  const record_we_want_to_associate
    .findOne({ id: req.params._id})
    .catch(err => {
      throw Error(err);
    });
  
  store.storeb_id = record_we_want_to_associate._id
  
  store
    .save()
    // after save return all records
    .then(stores => {
      return Store.find()
    })
    // then display them on index page    
    .then(stores => {
      res.render('index', {stores: stores}
    }
    // deal with errors
    .catch(err => {
      throw Error(err)
    }
}