Learning Note for Nest.js

nestjs.md

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Decorators

Decorator	Entity
@Request(), @Req()	req
@Response(), @Res()*	res
@Next()	next
@Session()	req.session
@Param(key?: string)	req.params / req.params[key]
@Body(key?: string)	req.body / req.body[key]
@Query(key?: string)	req.query / req.query[key]
@Headers(name?: string)	req.headers / req.headers[name]
@Ip()	req.ip
@HostParam()	req.hosts

Generators

• controller nest g controller users
• module nest g module users
• service nest g service users

Controller

• deal with incoming request and return response.
• generator nest g controller users

Module

• module is the place where you register your controller
• module is used to organize the codebase.
• module is always singleton.
• nest g controller users will automatically register controller in app.module.ts

Providers

• it can inject dependencies.(DI is a pattern following the Open-closed princile)
• include services, repositories,factories, helpers and so on.
• decorators: @Injectable

Services

• create a service nest g service users

Scope

• limit lifetime of providers within the application's lifetime
• for example. scope to a request lifttime.

Middleware

• called before the route handler
• the same in express
• config routes here

Exception

• nest has built-in gloabl error handler
• you can throw error with http code

@Get()
async findAll() {
  throw new HttpException({
    status: HttpStatus.FORBIDDEN,
    error: 'This is a custom message',
  }, HttpStatus.FORBIDDEN);
}

Questions

• What about naming conventions in Nest.js?