High level overview of Steps to make a MERN stack app(CRUD) - PART 3

Chapter 3 - MongoDB Atlas & Mongoose

1) Go to https://www.mongodb.com/atlas/database

2) Create an account (in case if you haven't already) then click on button Build a Database choose Free option(or any other) & create. Choose aws as Cloud provider & Region. In Cluster Name Give a name to cluster & Click Create Cluster button at bottom(let it complete).

3) In SECURITY-> Quickstart-> Username and Password- Create a new user(After Creating it can be accessed from SECURITY->Database Access) if you don't have one and also Add Current IP Address in SECURITY->Network Access.

4) Go to DEPLOYMENT->Database , you will see your cluster here in this we will create various collections corresponding to .js files in backend->routes folder like reddit.js

5) To connect our backend to created cluster(database)- click Connect->Connect your application & Copy Your Connection string and click close.

6) Go in your backend dir. go to .env file & create a new variable in it for connection string MONGO , also put your own password in place of <password> in string.

PORT=4000
MONGO=mongodb-v://<username>:<password>@<project>.126yh6uj88dgb3.mongodb.net/?retryWrite=true&w=maj

NOTE - ABOVE CONNECTION STRING IS EDITED USE YOUR OWN STRING DON'T COPY FROM HERE

7) In Terminal Git Bash while in dir.- .../backend install mongoose- npm i mongoose , mongoose basically connects backend to our database.

8) Go to server.js and using require import mongoose in variable mongoose and use mongoose.connect(process.env.MONGO).then(()=>{}).catch((error)=>{}) (It's Asynchronous hence returns a Promise after connecting to database so we use then & catch) to establish connection ( see the last part of code below to see mongoose.connect in action)

//call dotenv config function
require('dotenv').config()

const express=require('express')
const app=express()
const mongoose=require('mongoose') // HERE WE IMPORTED MONGOOSE!!!!!!!!!!!!!!

//Import the particular router from respective .js file from routes folder here
const redditRouter=require('./routes/reddit')

// global middleware
app.use((req,res,next) => {
console.log(req.path, req.method)
// calling next tells the control to go to next middlewares
next()
})
// middlewares with various routes

app.use(express.json()) // HERE WE ADDED IT!!!!!!!!!!!!!!!!!!!!!!!

app.use('/api/reddit',redditRouter)

app.get('/',(req,res)=>{ 
  res.json({apoo:'cxhxxn'}) 
})

// SET IF WE WANT STRICT SCHEMA OR NOT
mongoose.set('strictQuery', true)
// DB CONNECT HERE !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
mongoose.connect(process.env.MONGO)
  .then(()=>{
  // LISTEN TO REQUESTS ON SERVER AFTER CONNECTING TO DB !!!!!!!!!!!!!!!!!!!!!!!!!
  app.listen(process.env.PORT, () => {
 console.log(` already connected to DB & now listeneing on port ${process.env.PORT}!!!`)
})
  
})
  .catch((error)=>{
  console.log(error)
})

NOTE- we pass the connection string from earlier to mongoose.connect but to get res from database/establish connection it takes some time hence it's async in nature(also in case if you write MANGO instead of MONGO in process.env.MONGO or write your password wrong in connection str then it will throw an error that we .catch() and print to console) the callback function in .then() executes after connection is established, NOW THINK - SHOULD WE START LISTENING TO REQUESTS ON SERVER BEFORE OR AFTER CONNECTION IS ESTABLISHED? AFTER Ofcourse..... HENCE WE PUT our app.listen() from earlier inside the callback function of .then().

ALSO note that in terminal it might ask you to add a line just above mongoose.connect - mongoose.set('strictQuery', true) - Basically if second argument is true that means strict schemas & if it's false => non-strict schemas.

..... To be cont. in PART 4

High level overview of Steps to make a MERN stack app(CRUD) - PART 3

Chapter 3 - MongoDB Atlas & Mongoose

Grepper

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