Nodejs/NextJS reusable mongodb connection and CURD operations

mongodb.js

// MongoDB connection

import { MongoClient } from 'mongodb'; // install package first

const { MONGODB_URI/* connection string*/, MONGODB_DB /*db name*/ } = 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 exponentially
 * during API Route usage.
 */
let cached = global.mongo;

if (!cached) {
  cached = global.mongo = { conn: null, promise: null };
}

export async function connectToDatabase() {
  if (cached.conn) {
    return cached.conn;
  }

  if (!cached.promise) {
    const opts = {
      useNewUrlParser: true,
      useUnifiedTopology: true,
    };

    cached.promise = MongoClient.connect(MONGODB_URI, opts).then((client) => {
      return {
        client,
        db: client.db(MONGODB_DB),
      };
    });

    try {
      cached.conn = await cached.promise;
      if (!cached.conn) {
        console.log('ERROR: Database error.');
      }
    } catch (error) {
      console.log('ERROR: Database error.' + error);
    }
  }

  return cached.conn;
}

/**
 * Close the db connection
 */
export async function closeDatabase() {
  if (cached.conn) {
    await cached.conn.client.close();
    cached.conn = null;
    cached.promise = null;
  }
}

Fetching data using findOne

import { connectToDatabase } from './utils/mongodb';
  
export async function getUserDetails(email) {
  const { db } = await connectToDatabase();

  const findOptions = { email: email };
  const projection = {};

  const user = await db.collection('users').findOne(findOptions, projection);
  return user;
}