Use Mongoose with MongoDB in Ubuntu 19.10

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 Vultr's best practice guide here.

• Verify your server is up to date. Follow Vultr'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