const mongoose = require('mongoose');

mongoose.Promise = global.Promise;

let isConnected;

​

module.exports = connectToDatabase = () => {

  if (isConnected) {

    console.log('=> using existing database connection');

    return Promise.resolve();

  }

​

  console.log('=> using new database connection');

  return mongoose.connect(process.env.DB)

    .then(db => { 

      isConnected = db.connections[0].readyState;

    });

};