ULTIMATE BACKEND COURSE VIRTUAL CODE

What is Back-end Development ?

- Back-end development means working on server- side
software , which focuses on everything you can’t see on a
website.

- Focusing on databases , back-end logic , APIs ( Application

Programming interface ) and Servers.

- Programming Languages: JavaScript (Node JS) , Python (

Django/Flask ) , Java (Spring Boot) , PHP ( Laravel ) etc
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Client Database

Request
Response Server
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ULTIMATE
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Level-1 Introduction to Node JS

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Level-1 Introduction to Node JS

- Node JS is a JavaScript runtime Environment that allows

developers to run JavaScript code outside of a web Browser.

- Node JS runs on the V8 JavaScript Engine .

- Node JS is Used to create web Server etc.

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Level-1 Introduction to Node JS

Set-UP Node JS

Install Node JS

Install npm

Create folder

run npm init

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Level-2 Our First Server in Node

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Level-2 Our First Server in Node

- A Server is a computer or system that provides services ,

resources or data to other computers, called Clients , over
a network.

- Example-

- When you open a website, your browser ( the Client ) sends

a request to a server , and the server sends back the
website data so you can see it.
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Level-2 Our First Server in Node
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Level-2 Our First Server in Node
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Level-2 Our First Server in Node

Routing In Node JS -
- Routing is the process of defining how an application
responds to different client requests based on the URL
( or Route )

- Express JS simplifies route Creation

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Level-2 Our First Server in Node
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Level-3 Introduction to Express JS

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Level-3 Introduction to Express JS

- Express JS is the most Popular Framework of Node JS

- Instead of writing Everything manually with the node.JS

http module , Express JS gives you shortcuts and a cleaner
way to organize your code.

- Install Express JS package by Running this command-

npm install express

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Level-3 Introduction to Express JS

Creating Server using Express JS-

Importing express package

HTTP Method
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Level-3 Introduction to Express JS

HTTP methods-
- HTTP methods are used to handle various types of requests
made to a server.

- The most commonly used HTTP methods include-

1. GET Method - Used to retrieve data from the server

2. POST Method - Used to send data to the server( create

new resource )
3. PUT Method - Used to update an existing resource.
4. PATCH Method - Used to partially update a resource.
5. DELETE Method - Used to delete a resource
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Level-3 Introduction to Express JS

req.params -
- req.params is an object that stores route Parameters in
express JS.
- It is used to capture dynamic values from the URL.
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Level-3 Introduction to Express JS

req.query -
- req.query is an object that stores query parameters from the
URL.

- Query Parameter are sent as key-value pairs in the URL after

the ? Symbol and are typically used for filtering , searching
etc.
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Level-3 Introduction to Express JS

req.query -
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Level-4 Connect Backend with Frontend

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Level-4 Connect Backend with Frontend

RESTful API (Representational State Transfer ) –

- A RESTful API is a way for applications to communicate with
each other over the internet using standard HTTP requests
like GET, POST , PUT and DELETE.

- Client ( ex. A mobile app or Website) sends a request.

- Server receives the request and processes it.

- Server sends back a response ( usually in JSON format )

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Level-4 Connect Backend with Frontend

CORS (Cross Origin Resource Sharing) in express JS –

- CORS is a security feature in web browsers that prevents
requests from different origins unless explicitly allowed by
the server.

- Same-origin Policy restricts requests from different origins (

protocol, domain, or port )

- CORS allows servers to specify who can access their

resources.

npm install cors

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Level-5 Middlewares, Status Code and

HTTP Headers
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Level-5 Middleware, Status Code and HTTP Headers

Middlewares–
- Middleware runs before the route handler.
- Middleware must call next() to continue to the next function .
- If Middleware does not call next() , the request will hang.
- There are some built-in , custom , thirdparty middleware etc.

Third Party Middleware

Built-in Middleware

custom Middleware
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Level-5 Middleware, Status Code and HTTP Headers

Status Code –
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Level-5 Middleware, Status Code and HTTP Headers

HTTP Headers–
- HTTP Headers are key-value Pairs used in HTTP requests and
responses to pass additional information between the client and
the server.

- They help in defining metadata , specifying content type , setting

authentication tokens etc.

- Types of HTTP Headers :

1. Request Headers : Sent by the client to the server

( User-Agent)
2. Response Headers : Sent by the server to the client
( Content-Type)
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Level-5 Middleware, Status Code and HTTP Headers

HTTP Headers–
- Get request Headers:

1. req.get - for getting Specific Headers.

2. req.headers - for getting all headers.

- Set Response Headers: use res.set( ) or res.header( )

- Remove Headers : use res.removeHeader( headerName )

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Level-6 Introduction to MongoDB

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Level-6 Introduction to MongoDB

What is Database ? –
A database is a collection of data that allows storing ,managing
and retrieving information efficiently.

- Common used databases-

1. SQL database – MySQL, PostgreSQL ( stores data in tables )

2. NoSQL database – MongoDB ( Document Based )
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Level-6 Introduction to MongoDB

MongoDB–
- MongoDB is a NoSQL database that stores data in flexible ,
JSON – like format instead of tables.
NoSQL
ID Name Age
1 Ayush 21
2 Dev 22

SQL
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Level-6 Introduction to MongoDB

MongoDB–

Document 1

Collection

Document 2
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Level-6 Introduction to MongoDB

Database
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Level-6 Introduction to MongoDB

Mongoose –
- Mongoose is an ODM ( Object Data Modeling ) library for
MongoDB and Node JS.

- It helps developers interact with MongoDB using an easy an

Structured approach by defining schemas and models.

- Install Mongoose using -

npm install mongoose

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Level-6 Introduction to MongoDB
Set-UP MongoDB

Install mongoose

Connect DB

Design Schema

Create model based on Schema for

performing CRUD Operations
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Level-6 Introduction to MongoDB

Schema –
- A Schema in Mongoose defines the structure of documents
within a MongoDB collection .

- It specifies the fields , their types, validation rules , and

default values.

Model –
- A model is wrapper for schema and provides an interface to
interact with MongoDB Collection.
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Level-6 Introduction to MongoDB

Schema –
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Level-6 Introduction to MongoDB
Operation syntax
Create (Insert one) User.create({ })
Create (Insert many) User.insertMany([{ } , { }])
Read (Find All) User.find( )
Read (Find One) User.findOne({ })
Read (Find by ID) User.findById(“id”)
Update (one document) User.updateOne({ } , { })
Update (Find and Update) User.findOneAndUpdate({ },{ },{ })
Delete (One Document) User.deleteOne({ })
Delete ( Many Documents ) User.deleteMany({age : {$lt : 18} })
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Level-6 Introduction to MongoDB
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Level-6 Introduction to MongoDB
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Level-7 Authentication and Image Upload

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Level-7 Authentication & Authorization

Authentication –
- Verifies who a user is. ( Login & SignUp using email/password )

Authorization –
- Determines what a user can access .
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Level-7 Authentication & Authorization
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Level-7 Authentication & image Upload