mongoose is an Object Modeling library for mongoDB and node.js. It provides a straightforward, schema-based solution to model the application data and interact with mongoDB databases using JavaScript/TypeScript. It is specifically built for mongoDB (which is a NoSQL database).
Key Features of mongoose
- Schemas: Define the structure of the documents (like tables in SQL, but flexible). It is a kind of blueprint helpful to create Models. Schemas are defined using schema types. Valid schema types are: String, Number, Date, Buffer, Boolean, Mixed, ObjectId, Array, Map, etc.
- Models: Classes/compilations of schemas that let you create, read, update, delete documents.
- Validation: Built-in and custom validators for data. It saves lot of development time. Specify the validation rules in schemas, and mongoose automatically takes care the validations during CRUD operations.
- Population: This is another very useful feature. Similar to SQL JOINs – reference documents from other collections and populate them. For example, replace ObjectId references with actual documents.
- Query Builder: Rich, chainable query syntax.
- TypeScript support: Excellent official TypeScript typings.
- Plugins: Reusable pieces of functionality (e.g., timestamps, soft delete).
Where and why, we use mongoose?
We use mongoose primarily in node.js backend applications (especially with Express.js) that use mongoDB as the database. mongoose remains the de-facto standard for mongoDB in node.js because it gives you the perfect balance of flexibility (NoSQL) and structure/safety (schemas, validation, hooks) that raw drivers simply can’t match. Use it whenever you want your mongoDB backend to feel as mature and safe as a traditional SQL ORM — while still enjoying the speed and schema-less advantages of MongoDB.
Common Use Cases:
- Full-stack JavaScript apps (MERN stack: MongoDB, Express, React, Node.js)
- REST APIs
- Real-time applications (with Socket.io, etc.)
- Microservices that need a NoSQL database
- Any server-side JavaScript/TypeScript project requiring structured data with mongoDB
Example of a Simple Mongoose Usage:
1. Install mongoose
npm install mongoose
2. Connect to mongoDB
const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost:27017/mydb');3. Define a sample schema
const userSchema = new mongoose.Schema({
name: { type: String, required: true },
email: { type: String, unique: true, required: true },
age: { type: Number, min: 0 },
createdAt: { type: Date, default: Date.now }
});3. Create a model
const User = mongoose.model('User', userSchema);4. Use it
const newUser = new User({
name: 'John Doe',
email: 'john@example.com',
age: 25
});
newUser.save(); // Saves to MongoDB
const users = User.find({ age: { $gte: 18 } });
/Shijit/