connection.js

/*
 * Source: https://medium.com/@vimal.selvam/deploying-graphql-server-on-heroku-3e19dbdf4f51
 */

const mongoose = require("mongoose");

let connection = null;

const connectToDB = async () => {
  mongoose.Promise = global.Promise;

  let mongoUserCredentials = "";
  if (process.env.MONGO_USER && process.env.MONGO_PASSWORD) {
    mongoUserCredentials = `${process.env.MONGO_USER}:${
      process.env.MONGO_PASSWORD
    }@`;
  }

  const MONGO_URL = process.env.MONGO_URL || "localhost:27017";
  const DB_NAME = process.env.MONGO_DB_NAME || "testgraphql";
  const MONGO_CONNECTION_STRING = `mongodb://${mongoUserCredentials}${MONGO_URL}/${DB_NAME}`;

  await mongoose.connect(MONGO_CONNECTION_STRING);
  connection = mongoose;
};

const getDB = () => {
  if (!connection) {
    throw new Error("Call connectToDB first");
  }
  return connection;
};

module.exports = {
  connectToDB,
  getDB
};