mongodb.js

const path = require("path");
require("dotenv").config({
  path: path.join(__dirname, ".env.local"),
});
const { MongoClient, MongoError } = require("mongodb");

const { MONGODB_URI, MONGODB_DB } = process.env;

if (!MONGODB_URI) {
  throw new Error(
    "Please define the MONGODB_URI environment variable inside .env.local"
  );
}

if (!MONGODB_DB) {
  throw new Error(
    "Please define the MONGODB_DB environment variable inside .env.local"
  );
}

/**
 * Global is used here to maintain a cached connection across hot reloads
 * in development. This prevents connections growing exponentiatlly
 * during API Route usage.
 */

let cached = global.mongo;
if (!cached) cached = global.mongo = {};

async function connectToDatabase() {
  if (cached.conn) return cached.conn;
  if (!cached.promise) {
    const conn = {};
    const opts = {
      useNewUrlParser: true,
      useUnifiedTopology: true,
    };
    cached.promise = MongoClient.connect(MONGODB_URI, opts)
      .then((client) => {
        conn.client = client;
        return client.db(MONGODB_DB);
      })
      .then((db) => {
        conn.db = db;
        cached.conn = conn;
      });
  }
  await cached.promise;
  return cached.conn;
}

module.exports = { connectToDatabase };