/nestjs-notes

About this file

Notes about Nest.js

Nest.js key features

  • it surrounds your route handler body with try..catch blocks
  • it makes every route handler async
  • it creates a global express router
  • it creates a separated router for each controller
  • it binds error-handling middleware
  • it binds body-parser middleware (both json and extended urlencoded)

Nest.js key conventions

  • Keep all files as close to their domain (i.e. module folder) as possible
  • Follow this template when in doubt about anything

Naming conventions

Schnowa Jawab
TypeORM models modelName.entity.ts

CLI cheat sheet

nest generate module <name> nest generate controller <name> nest generate service <name>

Building blocks

Controllers

  • Declaration controls routing
  // users.controller.ts 

import { Controller, Get } from '@nestjs/common';

@Controller('users')
export class UsersController {
  @Get()
  async getBooks() { return [{book1}, {book2}] } 

  @Get(':bookID')
  async getBook(@Param('bookID') bookID) {}

  @Post()
  async addBook(@Body() createBookDTO: CreateBookDTO) {}

  @Delete()
  async deleteBook(@Query() query){ ...query.bookID... }
}

Providers

  • Just needs a @Injectable() decorator at top
    // users.service.ts

import { Injectable } from '@nestjs/common';
import { User } from './interfaces/user.interface';

@Injectable()
export class UsersService {
  private readonly users: User[] = [];

  create(user: User) { 
    this.users.push(user);   }

  findAll(): User[] {
    return this.users;
  }
}

Modules

... are TS files decorated with @Module decorator

  • Every Nest.js application has a root module
  • Plus normally submodules

Modus operandi

Dependency injection

constructor(private readonly usersService: UsersService){}
 ...
}

How to solve mindfucks

  • TypeORM module thinks options provided are for a mongodb database when it is actually for postgres. Mindfuck is to write ... 'postgres' as 'postgres'. Check this answer.

Resources

Good reads

Example codebases

Resources

How to get NestJS to do what Loopback does?

Resources: