MongoDB & Mongoose

Build and query MongoDB databases with best practices.

Quick Start

npm install mongodb mongoose

Native Driver

import { MongoClient, ObjectId } from 'mongodb';

const client = new MongoClient(process.env.MONGODB_URI!);
const db = client.db('myapp');
const users = db.collection('users');

// Connect
await client.connect();

// CRUD Operations
await users.insertOne({ name: 'Alice', email: '[email protected]' });
const user = await users.findOne({ email: '[email protected]' });
await users.updateOne({ _id: user._id }, { $set: { name: 'Alice Smith' } });
await users.deleteOne({ _id: user._id });

Mongoose Setup

import mongoose from 'mongoose';

await mongoose.connect(process.env.MONGODB_URI!, {
  maxPoolSize: 10,
  serverSelectionTimeoutMS: 5000,
  socketTimeoutMS: 45000,
});

// Connection events
mongoose.connection.on('connected', () => console.log('MongoDB connected'));
mongoose.connection.on('error', (err) => console.error('MongoDB error:', err));
mongoose.connection.on('disconnected', () => console.log('MongoDB disconnected'));

// Graceful shutdown
process.on('SIGINT', async () => {
  await mongoose.connection.close();
  process.exit(0);
});

Schema Design

Basic Schema

import mongoose, { Schema, Document, Model } from 'mongoose';

interface IUser extends Document {
  email: string;
  name: string;
  password: string;
  role: 'user' | 'admin';
  profile: {
    avatar?: string;
    bio?: string;
  };
  createdAt: Date;
  updatedAt: Date;
}

const userSchema = new Schema<IUser>({
  email: {
    type: String,
    required: [true, 'Email is required'],
    unique: true,
    lowercase: true,
    trim: true,
    match: [/^\S+@\S+\.\S+$/, 'Invalid email format'],
  },
  name: {
    type: String,
    required: true,
    trim: true,
    minlength: 2,
    maxlength: 100,
  },
  password: {
    type: String,
    required: true,
    select: false,  // Never return password by default
  },
  role: {
    type: String,
    enum: ['user', 'admin'],
    default: 'user',
  },
  profile: {
    avatar: String,
    bio: { type: String, maxlength: 500 },
  },
}, {
  timestamps: true,  // Adds createdAt, updatedAt
  toJSON: {
    transform(doc, ret) {
      delete ret.password;
      delete ret.__v;
      return ret;
    },
  },
});

// Indexes
userSchema.index({ email: 1 });
userSchema.index({ createdAt: -1 });
userSchema.index({ name: 'text', 'profile.bio': 'text' });  // Text search

const User: Model<IUser> = mongoose.model('User', userSchema);

Embedded Documents vs References

// ✅ Embed when: Data is read together, doesn't grow unbounded
const orderSchema = new Schema({
  customer: {
    name: String,
    email: String,
    address: {
      street: String,
      city: String,
      country: String,
    },
  },
  items: [