1. Nest.js

• Lifecycle
  • onModuleInit -> onApplicationBootstrap
  • onModuleDestroy -> onApplicationShutdown
• OVERVIEW
  1. Controllers
     • Request payloads: [DTO classes](https://docs.nestjs.com/controllers#request-payloads:~:text=A DTO is,variable at runtime.)
  2. Providers
     1. SOLID + Github, principle
     2. Dependency Injection(DI): One of Inversion of Control(IoC)
        1. Why DI: loosely coupled → fewer bugs and easier testing
     3. how to inject the provider
     4. Custom providers
  3. Modules
     1. Global module: If you have to import the same set of modules everywhere, Global modules should be registered only once, generally by the root or core module.
  4. Guards(with SECURITY-Authentication, RECIPES-Passport)
     1. Guard
        1. canActivate: logic to determine if the route should proceed or not. (verify JWT)
        2. Roles
     2. Passport
        1. Strategy
           • constructor: extract method and options
           • [validate](https://docs.nestjs.com/recipes/passport#:~:text=you verify whether a user exists (and/or create a new user)%2C and whether their credentials are valid.): you can add more validation logic or attach additional user data to the request.
  5. Interceptors
     1. AOP 먼저 이해하기.
  6. Custom decorators
     1. why need it: [reusable](https://docs.nestjs.com/custom-decorators#:~:text=reuse it across all of your controllers.)
• TECHNIQUES
  1. [Serialization](https://docs.nestjs.com/techniques/serialization#:~:text=Serialization is a process that happens before objects are returned in a network response.)
     1. sensitive data like passwords should always be excluded from the response.
     2. class-transformer
     3. 객체 안에 객체를 어떻게 접근할까?
  2. [Server-Sent Events](https://docs.nestjs.com/techniques/server-sent-events#:~:text=a server push technology enabling a client to receive automatic updates from a server via HTTP connection.)
     1. Notification
• SECURITY
  1. Authentication: JSON Web Token(JWT token), Refresh JWT
     1. JWT: Header.Payload.Signature for Access Token, Refresh Token
• RECIPES
  1. RouterModule: Routing defining a prefix at a module-level may come in handy.
  2. Passport
• FAQ
  1. Request lifecycle
     1. Middleware
     2. Guards
     3. Interceptors
     4. Pipes
     5. Filters: standard error message and semantic(RFC 7807), microservices

• Request lifecycle

  • Middleware: HTTP 요청과 응답 사이에서 단계별 동작을 수행하기 위해.

  • Pipe: for data transformation(e.g., from string to integer) and validation.

    파이프

• Configuration

  Configuration

• Task scheduler(Cron)

  • 주기적으로 반복적인 작업을 처리하기 위해.
  • reference(kor)

• Overview

  • custom decorators: use cases

• Techniques

2. TypeORM

Nest.js database

• Mapping: 1:1, 1:N, N:1, N:M → 관계형 데이터베이스를 위한 매핑.
• Datasource(v0.3.x)와 @InjectRepository()의 차이점: 성능으로 별 차이 없는 것 같음.
  • Access flow: DataSource → EntityManager → Repository
    • EntityManager is just like a collection of all entity repositories in a single place. You can access the entity manager via DataSource.
    • Repository is just like EntityManager but its operations are limited to a concrete entity. You can access the repository via EntityManager.
• Integration
  • forRoot and forRootAsync 차이 → 둘 다 다이나믹 모듈이고 걍 옵션이 다름.