Introduction to npm mongoose

Mongoose is a Node.js library used to manage MongoDB connections and perform various operations. It supports object modeling and schema definition with an API inspired by the well-known ORM tools.

Installation

To install Mongoose using npm, run this command:

npm install mongoose

Usage

To use Mongoose in your project, add the following code to import the module:

const mongoose = require('mongoose');

Connect to MongoDB

To connect Mongoose to your MongoDB server, use the connect method and specify the MongoDB URL.

mongoose.connect('mongodb://localhost/my_database', { useNewUrlParser: true , useUnifiedTopology: true });

Create a Schema

Before you can perform operations on a MongoDB collection, you need to define a schema that represents the data structure.

const userSchema = new mongoose.Schema({
  name: String,
  email: { type: String, unique: true },
  age: Number
});

Create a Model

With the schema defined, you can create a model that represents a MongoDB collection and provides an API to perform various operations on that collection.

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

Querying

You can perform MongoDB queries using various methods provided by Mongoose. For example, to find a user by their email address, you can use the findOne method:

const user = await User.findOne({ email: 'user@example.com' });

To find all users with a certain age, you can use the find method:

const users = await User.find({ age: 25 });

Create and Save

To create and save a new document to the database, you can use the create method:

const user = await User.create({
  name: 'John Doe',
  email: 'john.doe@example.com',
  age: 25
});

You can also create a new instance of a model and then save it:

const user = new User({
  name: 'John Doe',
  email: 'john.doe@example.com',
  age: 25
});

await user.save();

Update

To update an existing document, you can use the updateOne method:

await User.updateOne({ email: 'john.doe@example.com' }, { age: 30 });

Delete

To delete documents from the database, you can use the deleteOne or deleteMany methods:

await User.deleteOne({ email: 'john.doe@example.com' });

await User.deleteMany({ age: { $gte: 30 } });

Conclusion

Mongoose is a powerful MongoDB library that provides an easy-to-use API for managing connections, defining schemas, and performing database operations. With Mongoose, you can streamline your Node.js development and take full advantage of MongoDB's flexibility and scalability.