Mongoose
- Node.js course
- Advanced
- Lesson 25/83
- 5 min
Learn MongoDB connection with the Mongoose ODM.
What is Mongoose?
Mongoose is the most popular MongoDB ODM (Object Data Modeling) for Node.js. It lets you model MongoDB documents as JavaScript objects; it simplifies types, validation, and query building.
Install: npm install mongoose. Connect: mongoose.connect("mongodb://localhost:27017/mydb"). Mongoose is an abstraction over the raw MongoDB driver; you write safer queries with less code. It is a common choice in production.
Establishing a connection
To connect to MongoDB with Mongoose: mongoose.connect(uri). The URI format is mongodb://[user:pass@]host:port/dbname. The connection is asynchronous; you await it.
Connection state is read from mongoose.connection.readyState: 0 (disconnected), 1 (connected), 2 (connecting), 3 (disconnecting). You catch errors with mongoose.connection.on("error", cb). To close the connection call mongoose.disconnect(). In production the connection pool size is set with the { poolSize: 10 } option; this controls the number of concurrent queries.
Practice Log the type of mongoose
Import the mongoose module. Log typeof mongoose.
Starter code
// import the module
// log its typeSample solution
const mongoose = require("mongoose");
console.log(typeof mongoose);Expected output
object
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 How is Mongoose installed?
- npm install mongoose Correct answer
- pip install mongoose
- apt get mongoose
- brew mongoose
Explanation: Mongoose is installed with npm.
2 Complete the module name
const mongoose = require("____")const mongoose = require("mongoose")Explanation: The Mongoose module loads as 'mongoose'.
3 Match each piece to its role
| Term | Meaning |
|---|---|
mongoose |
MongoDB ODM |
npm install mongoose |
Installs the module |
require("mongoose") |
Imports the module |
mongoose.connect |
Connects |