Mongoose & MongoDB Skill
Master MongoDB database integration in Node.js with Mongoose, the elegant object modeling library.
Quick Start
Connect and CRUD in 4 steps:
Install - npm install mongoose Connect - mongoose.connect(uri) Define Schema - Create data models CRUD - Create, Read, Update, Delete Core Concepts Connection Setup const mongoose = require('mongoose');
mongoose.connect(process.env.MONGODB_URI, { useNewUrlParser: true, useUnifiedTopology: true });
mongoose.connection.on('connected', () => { console.log('MongoDB connected'); });
Schema & Model const userSchema = new mongoose.Schema({ name: { type: String, required: [true, 'Name is required'], trim: true, minlength: 3, maxlength: 50 }, email: { type: String, required: true, unique: true, lowercase: true }, age: { type: Number, min: 18, max: 120 }, role: { type: String, enum: ['user', 'admin'], default: 'user' } }, { timestamps: true // createdAt, updatedAt });
const User = mongoose.model('User', userSchema);
CRUD Operations // Create const user = await User.create({ name: 'John Doe', email: 'john@example.com' });
// Read const users = await User.find({ age: { $gte: 18 } }); const user = await User.findById(id); const user = await User.findOne({ email: 'john@example.com' });
// Update const updated = await User.findByIdAndUpdate( id, { name: 'Jane Doe' }, { new: true, runValidators: true } );
// Delete await User.findByIdAndDelete(id); await User.deleteMany({ age: { $lt: 18 } });
Relationships & Population const postSchema = new mongoose.Schema({ title: String, content: String, author: { type: mongoose.Schema.Types.ObjectId, ref: 'User' } });
// Populate relationship const post = await Post.findById(id).populate('author'); // post.author is now full user object
Learning Path Beginner (2-3 weeks) ✅ Install MongoDB and Mongoose ✅ Create schemas and models ✅ CRUD operations ✅ Basic queries Intermediate (4-5 weeks) ✅ Relationships and population ✅ Validation and middleware ✅ Indexes for performance ✅ Query operators Advanced (6-8 weeks) ✅ Aggregation pipelines ✅ Transactions ✅ Schema design patterns ✅ Performance optimization Advanced Features Indexes userSchema.index({ email: 1 }, { unique: true }); userSchema.index({ name: 1, age: -1 });
Middleware (Hooks) userSchema.pre('save', async function(next) { if (this.isModified('password')) { this.password = await bcrypt.hash(this.password, 10); } next(); });
Virtual Properties
userSchema.virtual('fullName').get(function() {
return ${this.firstName} ${this.lastName};
});
Aggregation Pipeline const stats = await User.aggregate([ { $match: { age: { $gte: 18 } } }, { $group: { _id: '$role', count: { $sum: 1 }, avgAge: { $avg: '$age' } }}, { $sort: { count: -1 } } ]);
Query Operators // Comparison User.find({ age: { $gt: 18 } }) // Greater than User.find({ age: { $gte: 18 } }) // Greater or equal User.find({ age: { $lt: 65 } }) // Less than User.find({ age: { $lte: 65 } }) // Less or equal User.find({ age: { $ne: 30 } }) // Not equal
// Logical User.find({ $and: [{ age: { $gte: 18 } }, { age: { $lte: 65 } }] }) User.find({ $or: [{ role: 'admin' }, { role: 'moderator' }] })
// Array User.find({ tags: { $in: ['node', 'mongodb'] } }) User.find({ tags: { $nin: ['deprecated'] } })
// Regex User.find({ email: /gmail.com$/ })
Best Practices ✅ Use environment variables for connection strings ✅ Create indexes for frequently queried fields ✅ Use lean() for read-only queries (better performance) ✅ Validate data at schema level ✅ Use transactions for multi-document operations ✅ Handle connection errors properly ✅ Close connections on app shutdown When to Use
Use MongoDB with Mongoose when:
Building Node.js applications Need flexible schema (document-based) Handling large volumes of data Rapid prototyping and iteration Working with JSON-like data Related Skills Express REST API (connect to MongoDB) Async Programming (async database operations) JWT Authentication (store users) Jest Testing (test database operations) Resources Mongoose Documentation MongoDB Manual Schema Design Patterns