The best way to Integrate the Node JS Application with MongoDB

July 1, 2021

Introduction

In this article you are going to learn about how to integrate a MongoDB database with an existing Node application.
Node.js has the ability to work with both MySQL and MongoDB as databases.
Before reading this article we have required basic knowledge of the Node JS platform.

Node JS: MongoDB Setup

Install the NodeJS mongoDB module by using the NPM (Node Package Manager).

$ npm install -g mongodb

Options

“-g” : Install this package globally
“Mongodb” : Install Node JS MongoDB module.

Verify the MongoDB successfully installed

Enter the following command on your command prompt.
```
$ mongo
```
This will drop you into an administrative shell.

Adding Mongoose and Database Information to the Project

Add the npm package mongoose to the project with the npm install command:

$ npm install mongoose

Mongoose gives you the built-in methods, which you will use to create the connection to your database.
Before creating your mongoose schemas and model you need to make connections with the database. We will add our database connection information to our application.
Create one file database_info.js inside the project.
Add the following constants in the database_info.js file
‘mongoose’ give you access to Mongoose’s built-in methods

const mongoose = require('mongoose');


const MONGO_DB_USERNAME = 'sandip;
const MONGO_DB_PASSWORD = '1234';
const MONGO_DB_HOSTNAME = '127.0.0.1';
const MONGO_DB_PORT = '27017';
const MONGO_DB = 'studentInfo';

Add the DB connection information to the App.js file so that the application can use it.

const express = require('express');
const app = express();
const router = express.Router();
const path = __dirname + '/views/';
const router = express.Router();

const db = require('./database_info);

const path = __dirname + '/views/';

How to create Mongoose Schemas and Models

Create the ‘modules’ directory inside your project.
Add the ‘Student.js’ model inside the models folder

const mongoose = require('mongoose');
const Schema = mongoose.Schema;
const Student = new Schema ({
        email: { type: String, required: true },
        character: { type: String, required: true },
});

module.exports = mongoose.model('Student', Student)

Imported the ‘mongoose’ at the top line
Schema object is defined in the second line.
Defined the fields which are required in the schema
In the last line, We need to call the model constructor on the Mongoose instance and pass it the name of the collection and a reference to the schema definition.
You can also make the email attribute unique, required by using the following options

let emailSchema = new mongoose.Schema({

  email: {

    type: String,

    required: true,

    unique: true,

    lowercase: true,

    validate: (value) => {

      return validator.isEmail(value)

    }

       }

})

Add the validation function that will ensure that the value is a valid email address.

Basic Operations on MongoDB

Create the controller to perform the operations:

nano controllers/studentController.js

Create Operation:

Create function used to create the document in the DB

exports.create = function (req, res) {

    var student = new Student(req.body);

    student.create(function (err) {

        if(err) {

            console.log(“Failed to create”);

        } else {

            console.log(“Create Successfully..!!”);

        }

  });

};

Fetch All Records:

Find command is used to fetch all the records

exports.list = function (req, res) {

        Student.find({}).exec(function (err, res) {

                if (err) {

                        console.log(“Failed to fetch”);

                }

else {

console.log(“Records fetched”);

    }

              );

        });

};

Mongoose has a very rich API set that handles many complex operations supported by MongoDB.

StudentModel.find()                   

         .skip(100)                

         .limit(10)                

         .sort({firstName: 1}      

         .select({firstName: true} 

         .exec()                   

         .then(docs => {

            console.log(docs)

          })

         .catch(err => {

            console.error(err)

          })

find: Find all users
skip : Skip the first 100 records
limit: Limit the results to 10 records
sort: Sort the results by the firstName field
select: Select the firstName
exec : Execute the query