Introduction

This tutorial will guide you on the best practices for using MongoDB with Express.js. It aims to help you understand the ways to effectively use MongoDB and Mongoose in your Express.js application.

By the end of this tutorial, you'll learn:
- How to connect MongoDB with Express.js
- Best practices for data modeling and query optimization
- Error handling techniques
- Tips for secure connections

Prerequisites for this tutorial are basic knowledge of Express.js, Node.js and JavaScript. Familiarity with MongoDB is beneficial, though not strictly necessary.

Step-by-Step Guide

Connecting MongoDB with Express.js

The first step is connecting MongoDB with Express. We use Mongoose, a MongoDB object modeling tool, to create models and query the database.

const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/test', {useNewUrlParser: true, useUnifiedTopology: true});

Schema Design

In MongoDB, it's essential to design your schema according to the application's needs. If you need to perform lots of queries for a particular data set, it's better to denormalize your data. Here's an example:

const userSchema = new mongoose.Schema({
  name: String,
  email: String,
  posts: [{
    type: mongoose.Schema.Types.ObjectId,
    ref: 'Post'
  }]
});

Query Optimization

Always use lean queries when you don't need a fully-fledged Mongoose document. It returns plain JavaScript objects, not Mongoose documents, which makes it faster.

User.find().lean().exec((err, users) => {
  console.log(users); // an array of plain objects
});

Error Handling

Always handle errors effectively. Here's an example:

User.find((err, users) => {
  if (err) {
    console.error(err);
    return;
  }
  console.log(users);
});

Code Examples

Example 1: Creating a Model

const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/test', {useNewUrlParser: true, useUnifiedTopology: true});

const userSchema = new mongoose.Schema({
  name: String,
  email: String
});

const User = mongoose.model('User', userSchema);

Example 2: Inserting a document

const user = new User({ name: 'John Doe', email: 'john@doe.com' });
user.save((err, result) => {
  if (err) {
    console.error(err);
    return;
  }
  console.log(result); // the saved user
});

Summary

In this tutorial, we've covered how to connect MongoDB with Express.js, best practices for schema design and query optimization, and efficient error handling. Next, you can learn more about advanced schema design, complex queries, and transaction handling in MongoDB.

Here are some resources for further learning:
- Mongoose Docs
- MongoDB Docs
- Express.js Docs

Practice Exercises

1. Exercise 1: Create a new Express.js application and connect it with a MongoDB database.
2. Exercise 2: Create a new User model with fields name, email, password, and dateRegistered. Insert a new user into the database.
3. Exercise 3: Retrieve all users from the database and print them to the console.

Remember to handle all errors properly and optimize your queries. Happy coding!