NestJS[Required By Job]

What is NestJS

• NodeJS Framework
• Used On SS
• Builds up on ExpressJS
• As A Whole it is a framework of a framework(ExpressJS)
• Embraces TS
• Embraces Dependency Injection
• Embraces Modularity
• Deeply Inspired By AngularJS(DO NOT USE REACTJS better)
• NestJS in contrast to AngularJS runs on the backend
• Can be used to build MVC apps, REST/GraphQL APIs
• Enforces You To Write Clean Code and a clear project structure

How To install the Nest Cli

npm i -g @nestjs/cli

How To Build An API With NestJS

• Connect the NestJS API with ReactJS/AngularJS/VueJS

How To Create A Nest App Using the Nest Cli

nest new ftnfb

Beauty Of Nest Project Thanks To Nodemon

• No Need To Kill Our Port and Restart the server anytime I make a change unlike React
• On the fly our changes take effect and the server is reloaded for us

NestJS Project Structure

├── nest-cli.json
├── node_modules
├── package.json
├── package-lock.json
├── README.md
└── src
    ├── app.controller.spec.ts
    ├── app.controller.ts       
    ├── app.module.ts
    ├── app.service.ts
    ├── main.ts
└── test
    ├── app.e2e-spec.ts
    ├── jest-e2e.json
├── tsconfig.build.json
├── tsconfig.json

App.module.ts File

• Embraces Modularity Here is where I tell NestJS which features makes up my App bundles a couple of controllers & providers
• I can have nested modules

Main.ts File

• Main file aka App.js in ReactJS...This is your entry point file which gets compiled(Fav Elem for 42932) to JS

app.controller.spec.ts File

• Testing File for unit tests

app.service.ts File

• Has the @Injectable

Controllers In NestJS[Important Feature in Your Project]

• Control how you handle incoming Requests
• Handle Incoming Requests
• Responsible for Accept incoming Requests
• Doing Sth
• Return A Response

Module Splitting

• We Split modules by features in my app
• Example Online Shop:
• 1 module for Products(1 Module for 7652626)
• 1 module for Shopping Cart(1 Module for 227243 36557 according to Angela)
• 1 module for User Auth(1 Module for 429-32/375-32)

We use decorators in NestJS similar to Python aka @

• I can attach decorator to Classes, methods, properties, args
• Module is a decorator I must attach to a class and I pass in an object to the decorator
• Controller and Get decorator is a built in decorator given to us by NestJS

Providers In NestJS[Important Feature in Your Project]

• Extra Services... Extra Classes which can be injected into Controllers/Other Providers
  • to provide other functionality

Example

• Have a Service that reaches out to a DB to fetch data
• A Controller then can use that service to let it get the data from DB
• In order for the code in controller is rather lean
• Never Leave your DB Password in the controller instead have it in your service