Knowledgebase

Introduction

Mongoose is an ODM (Object Data Modeling) library built on top of the MongoDB driver. It allows for concise interaction with MongoDB and simple object modeling within a NodeJS environment.

Prerequisites

Before starting, it is recommended that you:

• Set up a non-root user with sudo privileges. Follow Rcs's best practice guide here.

• Verify your server is up to date. Follow Rcs's best practice guide here.

• Make sure build-essential is installed. If not, install using:

    $ sudo apt install build-essential

1. MongoDB

Install MongoDB.

$ sudo apt install mongodb

Verify it was installed properly. Look for "active (running)" in the output.

$ sudo systemctl status mongodb
Active: active (running)

2. NodeJS and NPM

Add the latest stable NodeJS repository.

$ curl -sL https://deb.nodesource.com/setup_12.x | sudo -E bash -

Install NodeJS.

$ sudo apt install nodejs

Verify NodeJS and NPM are installed properly.

$ node -v && npm -v
v12.x.x
6.x.x

3. Initialize the Mongoose Project

Create the project root directory.

$ cd ~
$ mkdir mongooseProject && cd mongooseProject

Initialize a NodeJS development environment to automatically generate a package.json:

$ npm init

Answer the short questions to fit your project. For example, if you press return at each question to accept the defaults, the npm init process responds:

About to write to /root/mongooseProject/package.json:

{
"name": "mongooseproject",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
},
"author": "",
"license": "ISC"
}

Install the required packages using npm in the project root directory:

$ npm install --save mongoose

4. Define a Model

Create a folder called Models in the root directory of the project and cd into it:

$ cd ~/mongooseProject
$ mkdir Models && cd Models

Create connectDB.js. This file will contain the connection logic needed for the MongoDB server.

$ nano connectDB.js

Paste the following into connectDB.js.

const mongoose = require('mongoose'); // Import mongoose library

module.exports = function(uri) {
    mongoose.connect(uri, {  //attempt to connect to database
        useNewUrlParser: true, // Recommended, insures support for future MongoDB drivers
        useUnifiedTopology: true // Recommended, uses new MongoDB topology engine
    }).catch(error => console.log(error)) // Error handling


    mongoose.connection.on('connected', function () { // On connection
        console.log('Successful connection with database: ' + uri); // Callback for successful connection
    });
}

Create Users.js. This file will contain the model for the database collection Users.

$ nano Users.js

Paste the following into Users.js. This defines a basic schema for users.

const mongoose = require("mongoose"); // Import mongoose library
const Schema = mongoose.Schema // Define Schema method

// Schema
var UsersSchema = new Schema({ // Create Schema
    name: String, // Name of user
    age: Number, // Age of user
    role: String // Role of user
})

// Model
var Users = mongoose.model("Users", UsersSchema) // Create collection model from schema
module.exports = Users // export model

5. Insert Documents into MongoDB

Create insertUser.js in the root directory of the project.

$ cd ~/mongooseProject
$ nano insertUser.js

Paste the following into insertUser.js file. This file inserts documents into the Users collection.

//Library
const mongoose = require("mongoose")

// Database connection
const connectDB = require("./Models/connectDB")
var database = "mongoose" // Database name

// Models
const Users = require("./Models/Users")

// Connect to database
connectDB("mongodb://localhost:27017/"+database)

var insertedUser = new Users({ // Create new document
    name: "John Doe",
    age: 18,
    role: "Example User"
})

insertedUser.save(err => { // save document inside Users collection
    if(err) throw err // error handling
    console.log("Document inserted!")
    mongoose.disconnect() // disconnect connection from database once document is saved
})

Run insertUser.js.

$ node insertUser.js
Successful connection with database: mongodb://localhost:27017/mongoose
Document inserted!

6. Read Documents from MongoDB

Create readUsers.js in the root directory of the project.

$ cd ~/mongooseProject
$ nano readUsers.js

Paste the following into readUsers.js. This file reads documents in the Users collection.

//Library
const mongoose = require("mongoose")

// Database connection
const connectDB = require("./Models/connectDB")
var database = "mongoose" // Database name

// Models
const Users = require("./Models/Users")

// Connect to database
connectDB("mongodb://localhost:27017/"+database)

Users.find({}, (err, users)=>{ //find and return all documents inside Users collection
    if(err) throw err // error handling
    console.log(users)
    mongoose.disconnect()
})

Run readUsers.js. The output is an array of objects.

$ node readUsers.js
Successful connection with database: mongodb://localhost:27017/mongoose
[ { _id: ************************,
    name: 'John Doe',
    age: 18,
    role: 'Example User',
    __v: 0 } ]

Conclusion

You have set up Mongoose to work with MongoDB. For more information, please see the Mongoose API documentation