Connecting MongoDB to Node JS | Learn MERN Stack

 Step 1 :  SignUp and create a cluster

> Go to MongoDB Website and Create an account - https://www.mongodb.com/

> Create a Project

> Create a Cluster 

• Shared
• Cloud Provider - AWS
• Region - anywhere you like

> Click on Create Clustor

Step 2 : Create an Database

Now the cluster takes 2-3 minutes to create, so by that time let's setup our database

> Got to Database Access

> Add New Database User - setup id and password for the database

> click on create

Step 3: Create Network Access

> Choose "Allow access from anywhere"

> Click on create

Step 4 : 

Now that our cluster is created,

>Go to Database > click on the "Connect" button

> Choose " connect our application"

> Copy the " connection-string "

NOW GO BACK TO YOUR VS CODE EDITOR

Step 5 : 

> go to mern-stack/backend 

>Install Mongoose - npm i mongoose

> Open .env file 

> Create a new variable and paste the "connection string" you just copied"

>.env file : 

PORT = 7000

MONGO_URI = "mongodb+srv://aatu020:<password>@cluster0.t0wil.mongodb.net/myFirstDatabase?retryWrites=true&w=majority"

(Makes sure to replace <password> with your database password)

Step 6 : Creating a Database Connection 

>Create a file name "config" inside backend

> Navigate to notes-saver/backend/config

>Create a java script file with the name "db.js'  (any name is fine)

db.js file - 

------------

const mongoose = require("mongoose");

const connectDB = async () => {

  try {

    const conn = await mongoose.connect(process.env.MONGO_URI);

    console.log(`db connected : ${conn.connection.host}`);

  } catch (e) {

    console.log(`Erro : ${e.message}`);

    process.exit();

  }

};

module.exports = connectDB;

>Go to server.js - 

const express = require("express");

const dotenv = require("dotenv");

const notes = require("./Data/notes");

const { connect } = require("mongoose"); //this is added

const connectDB = require("./config/db"); //this is added

const app = express();

dotenv.config();

connectDB(); //this is added

app.get("/", (req, res) => {

  res.send("API is running");

});

app.get("/api/notes", (req, res) => {

  res.send(notes);

});

const PORT = process.env.PORT || 5000;

app.listen(PORT, console.log(`server started at ${PORT}`));

How do terminal looks -

And connection is successful.

Hurray! You have successfullyestablished the database connection(mongoDB) with backend (nodejs)