NESTJS FLOW

End to end build a project with NestJS. This series demo is just for purpose learning or practice NestJS.

All branches of projects

Init project: Controller, services, modules
Database, typeorm
Auth with passpord, jwt
Error handling & data validation
Serializing response with interceptors
Database relationship
Unit testing, integration testing
End to end testing
Upload file to Amazon s3(Public bucket)
Managing private files with amazon S3 (Private bucket)
Elastic search
Implement refresh token jwt
Explore SQL database with indexes, transactions, array data type
Exploring idea of microservices (TCP Layer, RabbitMQ, gRPC framework)
Pattern Command-Querry-Responsibility-Segregation (CQRS)
Storing JSON with PostgresSQL & TypeORM
Implementing in-memory cache to increase the performance
Cache with Redis. Running the app in a Nodejs cluster

Table of content

NESTJS FLOW

When we work with Nodejs in big projects, the project structure become so important. So if you love typescript, NestJS will help you resolve this problem.

So what is NestJS?

Nest (NestJS) is a progressive Nodejs framework (open-source) for building efficient, scalable, testable. It is built with and fully supports TypeScript and combines elements of OOP (Object Oriented Programming), FP (Functional Programming), and FRP (Functional Reactive Programming). It use many strong design pattern: Dependency injection, MVC, micro services, CQRS pattern ...

Nest has many features out of box to help you make your project become ready-production quickly.

Check Nest for more information.

Now we will start with a simple REST API project with NestJS from basic to advance.

Each big step will separate by each branch of git.

1. Init project

Click to expand section

Check the code at branch 1-init-project

Installation

Install Nest CLI

$ yarn global add @nestjs/cli
$ nest new project-name

or alternatively, to install the TypeScript project wiht Git:

$ git clone https://github.com/nestjs/typescript-starter.git project
$ cd project
$ npm install
$ npm run start

Check Nestjs documentations for more details

Start coding

Bootstrap projects

Init project with Nest CLI

$ nest new nestjs-flow
$ cd nestjs-flow

When all done, we will have a structure project:

  .
├── nest-cli.json
├── package.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
└── yarn.lock

Check the Nest documentation, you will have a very good explain about structure, about each files & understand how it works.

Note: when you create project with Nest cli, it will be automatically include a file .git in the root folder. Consider delete it with rm -rf .git if you have already another .git.

Note2: if you create Nestjs as a subfolder in your project (as microservice eg), you will have some problem with eslint syntax. To fix that, update tsconfigRootDir: __dirname in .eslint.js file

//.eslintrc.js
  parserOptions: {
    project: 'tsconfig.json',
+  tsconfigRootDir: __dirname,
    sourceType: 'module',
  },

Start server Run yarn start:dev to start server. Check all scripts availables in package.json file.

Custom port server Default port of server nest js: 3000, you can change it as you cant in main.ts. Here, I use port 1776:

//main.ts
import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  await app.listen(1776, () => {
    console.log(`Server is running at http://localhost:1776/`);
  });
}
bootstrap();

Using variable environment (.env)

If you are familiar with Nodejs, you may be sûre already know dotenv package to manage variable environment (secret variable) in .env files.

Nest JS also help us to handle that with @nestjs/config.

Install Add to the DevDependencies
```
$ yarn add -D @nestjs/config
```

Setup We will import the ConfigModule in app.modules.ts:

//app.module.ts
import { Module } from '@nestjs/common';
import { ConfigModule } from '@nestjs/config';

@Module({
  imports: [ConfigModule.forRoot()],
})
export class AppModule {}

ConfigModule is setup global (for all files) by default. You can customize to more readable:

// app.module.ts
...
imports: [
  ConfigModule.forRoot({
    isGlobal: true,
    envFilePath: '.env',
  }),
  ...
],
...

Then, when server started, the config will initialize automatically.

How it works The principe of @nest/config is the same as dotenv. That means we can use process.env to call the variable.

ex: in the .env file we have:
```
DATABASE_USER=test
DATABASE_PASSWORD=test
```
==> use process.env.DATABASE_USER , process.env.DATABASE_PASSWORD

To better use process.env variables, we will create a global declaration type file.

Create node.d.ts file to declare Nodejs type in src/common/types folder and add the variables you declare in your .env files

# .env file
SERVER_PORT=1776
ROUTE_GLOBAL_PREFIX=api
JWT_SECRET=justanotherkey

# Typeorm
TYPEORM_CONNECTION = postgres
TYPEORM_HOST = postgres
TYPEORM_USERNAME = postgres
TYPEORM_PASSWORD = postgres
TYPEORM_DATABASE = test_db
TYPEORM_PORT = 5432

TYPEORM_ENTITIES = [src/modules/**/*.entity.ts]
TYPEORM_MIGRATIONS=[src/common/migrations/**/*.ts]
TYPEORM_MIGRATIONS_DIR=src/common/migrations

// src/common/types/node.d.ts
declare namespace NodeJS {
  interface ProcessEnv {
    readonly NODE_ENV: 'development' | 'production' | 'test';
    readonly SERVER_PORT: string;
    readonly TYPEORM_CONNECTION: string;
    readonly TYPEORM_HOST: string;
    readonly TYPEORM_USERNAME: string;
    readonly TYPEORM_PASSWORD: string;
    readonly TYPEORM_DATABASE: string;
    readonly TYPEORM_PORT: string;
    readonly TYPEORM_LOGGING: string;
    readonly TYPEORM_ENTITIES: string;
    readonly TYPEORM_MIGRATIONS: string;
    readonly ROUTE_GLOBAL_PREFIX: string;
    readonly JWT_SECRET: string;
    readonly TWO_FACTOR_AUTHENTICATION_APP_NAME: string;
  }
}

And update your tsconfig.json files:

"typeRoots": [
    "./node_modules/@types",
    "src/common/types"
  ],

So, now, each time you call process.env, all variables environments will be suggested.

For more details check on Nest configuration.

Modules

In the template create by Nest cli, there are not many thing to do with. So, we will create a simple api blog to understand easier how NestJS work.

I recommend structure src project as:

├── src
│   ├── app
│   │   ├── app.controller.spec.ts
│   │   ├── app.controller.ts
│   │   ├── app.module.ts
│   │   └── app.service.ts
│   ├── common
│   │   ├── config
│   │   └── types
│   │       └── node.d.ts
│   ├── main.ts
│   └── modules
│       ├── auth
│       ├── post
│       └── user

app: contains all files of app modules
common: contains common or shared files as types, config, migration, data, interface general ...
modules: container where contains all files of each modules of project. ex: User module, auth module, post module ...

This structure will help you better organize your codes & adapt with principle of Nest framework. If you follow this series, you will understand better why I prefer this structure.

Post modules

Getting started Docs of Nest is very well structure and excellent explain all techniques & theirs features. So I will not go deep to explain each one. When you read my codes, if you don't understand some parts, you can check for more details:
- Controllers: where you put your routes
- Providers: services files contains methods to connect with methods of repository (database), it help use to separate business logic from controllers
- Modules: combine of controllers & providers to export

Create PostService For the first step, we will create a simple Post module. We will not use the database now and we use the fake array instead.

Add package uuid to create fake id
```
$ yarn add -D uuid
```
Create folder src/modules/post

Create post.interface.service for post model

// post.interface.ts
export interface Post {
  id: string;
  title: string;
  content: string;
}

Create src/post/dto: data transfer object --> to handle data between class data & body request

// create-post.dto.ts
export class CreatePostDto {
  title: string;
  content: string;
}

// update-post.dto.ts
export class UpdatePostDto {
  title?: string;
  content?: string;
}

For UpdatePostDto we make nullable for the field to permit update partial.

We convert data between class typescript & body request, so we need add package class-transformer. Nest will help use convert them automatically.
```
$ yarn add class-transformer
```

Create post.service.ts from PostService

import { Injectable, NotFoundException } from '@nestjs/common';
import { CreatePostDto, UpdatePostDto } from './dto';
import { Post } from './post.interface';
import { v4 as uuid } from 'uuid';

@Injectable()
export class PostService {
  private posts: Post[] = [];

  public async getPosts(): Promise<Post[]> {
    return this.posts;
  }

  public async getPostById(id: string): Promise<Post> {
    const post = this.posts.find((p) => p.id === id);
    if (!post) {
      throw new NotFoundException(`Post with id ${id} not found`);
    }
    return post;
  }

  public async createPost(postDto: CreatePostDto): Promise<Post> {
    const post: Post = {
      ...postDto,
      id: uuid() as string,
    };
    this.posts.push(post);
    return post;
  }
   public async updatePost(id: string, postDto: UpdatePostDto): Promise<Post> {
    const post = this.posts.find((p) => p.id === id);
    if (!post) {
      throw new NotFoundException(`Post with id ${post.id} not found`);
    }
    const updated = Object.assign(post, postDto);
    const postIndex = this.posts.findIndex((p) => p.id === post.id);
    this.posts[postIndex] = updated;
    return updated;
  }

  public async deletePost(id: string): Promise<void> {
    const postIndex = this.posts.findIndex((p) => p.id === id);
    if (postIndex < 0) {
      throw new NotFoundException(`Post with id ${id} not found`);
    }
    this.posts.splice(postIndex, 1);
  }
}

In this post service, we will create the CRUD method work with a simple posts array.

Note: If you ask what is @Injectable() at above of class PostService?. It is a class decorator for provider use Dependency injection (or inversion of injection). We will use that to inject easily in controller file.

For more details, check Custom providers, Injection scopes & Circular dependency of Nest.

Create PostController Ok now, we will use the methods of PostService in PostController

// post.controller.ts
import {
  Controller,
  Body,
  Get,
  Post,
  Put,
  Delete,
  Param,
} from '@nestjs/common';
import { CreatePostDto, UpdatePostDto } from './dto';
import { PostService } from './post.service';

@Controller('posts')
export class PostController {
  constructor(private readonly postService: PostService) {}

  @Get()
  public async getPost() {
    return await this.postService.getPosts();
  }

  @Get('/:id')
  public async getPostId(@Param('id') id: string) {
    return await this.postService.getPostById(id);
  }

  @Post('/')
  public async createPost(@Body() postDto: CreatePostDto) {
    return await this.postService.createPost(postDto);
  }

  @Put('/:id')
  public async updatePost(
    @Param('id') id: string,
    @Body() postDto: UpdatePostDto,
  ) {
    return await this.postService.updatePost(id, postDto);
  }

  @Delete('/:id')
  public async deletePost(@Param('id') id: string) {
    return await this.postService.deletePost(id);
  }
}

Note:

Make sure you use @Controller('...') decorator for class PostController
You can also use Nest CLI for simplify this tâche.

Create PostModule

// post.module.ts
@Module({
  imports: [],
  controllers: [PostController],
  providers: [PostService],
})
export class PostModule {}

Check Nest module

Import PostModule in AppModule.

import { PostModule } from '@modules/post/post.module';
import { Module } from '@nestjs/common';
import { AppController } from './app.controller';
import { AppService } from './app.service';
import { ConfigModule } from '@nestjs/config';

@Module({
  imports: [
    ConfigModule.forRoot({
      isGlobal: true,
      envFilePath: '.env',
    }),
    PostModule,
  ],
  controllers: [AppController],
  providers: [AppService],
})
export class AppModule {}

Run server yarn start:dev & test routes with Postman

Create newt post:

Get all posts:

...

2. TypeORM

Click here to expand section

Check the code at branch 2-typeorm

In the first part, we are used an array to fake database. In this part, we will use the real database PostgreQL with TypeORM.

TypeORM is an object relation mapping (open source) for Database SQL (SQlite, PostgreSQL, MySQL, MSSQL and also for mongodb). It make the work more easier with SQL query.

You can consider use Prisma - the next generation of TypeORM. It is a awesome tool, solve many trouble of TypeORM. But there are some interesting features is under preview version.

Install dependencies
```
$ yarn add @nest/typeorm typeorm pg
```

Config ORM Update variables in .env file

SERVER_PORT=1776
ROUTE_GLOBAL_PREFIX=/api
JWT_SECRET=justanotherworld

# Typeorm
TYPEORM_CONNECTION = postgres
TYPEORM_HOST = postgres
TYPEORM_USERNAME = postgres
TYPEORM_PASSWORD = postgres
TYPEORM_DATABASE = test_db
TYPEORM_PORT = 5432
TYPEORM_ENTITIES = [src/modules/**/*.entity.ts]

# For run migration cli
TYPEORM_MIGRATIONS=[src/common/migrations/**/*.ts]
TYPEORM_MIGRATIONS_DIR=src/common/migrations

Create src/common/config/ormConfig.ts

// ormConfig.ts
export function ormConfig(): any {
return {
    type: process.env.TYPEORM_CONNECTION,
    host: process.env.TYPEORM_HOST,
    port: Number(process.env.TYPEORM_PORT),
    username: process.env.TYPEORM_USERNAME,
    password: process.env.TYPEORM_PASSWORD,
    database: process.env.TYPEORM_DATABASE,
    autoLoadEntities: true,
    entities: [join(__dirname, '**', '*.entity.{ts,js}')],
    logging: false,
    synchronize: true,
  };
}

As we setup ConfigModule with @Nestjs/Config, so now we can use directly process.env to access directly variable environment;

Note: Check Nest database or Typeorm to understand how to config that.

type: sql driver as: postgres, mysql, mssql, mongodb ...
host: host of your database (localhost eg.)
username & password: permission user to controler database
database: name of database that you use for this project
logging: logging when query database in the terminal (recommend: false)
synchronize: true. It means all the modification in entities will synchronize automatically with your database. Attention for this feature: It will be very dangerous. You can be lost your data, should use only for develop phrase.
entities: an arry to indicate where stock entity files

If you don't want synchronize automatically, you need consider use cli to make the migrations.

Import ormConfig in app.module

//app.module.ts
import { PostModule } from '@modules/post/post.module';
import { Module } from '@nestjs/common';
import { AppController } from './app.controller';
import { AppService } from './app.service';
import { ConfigModule } from '@nestjs/config';
import { TypeOrmModule } from '@nestjs/typeorm';
import { ormConfig } from '@common/config/ormConfig';

@Module({
  imports: [
    ConfigModule.forRoot({
      isGlobal: true,
      envFilePath: '.env',
    }),
    TypeOrmModule.forRoot(ormConfig()),
    PostModule,
  ],
  controllers: [AppController],
  providers: [AppService],
})
export class AppModule {}

Post modules

Create Post entity: src/modules/post/post.entity.ts Before create a post, we need add moment-timezone to handle date with timezone for column date.

// post.entity.ts
import { BaseEntity, Column, Entity, PrimaryGeneratedColumn } from 'typeorm';
import moment from 'moment-timezone';
@Entity()
export class Post extends BaseEntity {
  @PrimaryGeneratedColumn('uuid')
  id: string;

  @Column()
  title: string;

  @Column()
  content: string;

  @Column({
    type: Date,
    default: moment(new Date()).format('YYYY-MM-DD HH:ss'),
  })
  createdAt;

  @Column({
    type: Date,
    default: moment(new Date()).format('YYYY-MM-DD HH:ss'),
    nullable: true
  })
  updatedAt;
}

In the previous part, we use uuid package to create fake uuid. But typeorm already provide a decorator method: @PrimaryGeneratedColumn(uuid). If you only want to create id: number, you just use: @PrimaryGeneratedColumn(id)

Decorator method @Column is equivalent a column of table.

Check Database for more details.

Using PostEntity & PostRepository in PostService

Now we will modify the old code of first part, and update theme with typeorm solution.

As we know, Nest use strongly dependency injection pattern, it provide also for inject Repository too --> (@InjectRepository(Entity))

// post.service.ts
import { Injectable, NotFoundException } from '@nestjs/common';
import { CreatePostDto, UpdatePostDto } from './dto';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository } from 'typeorm';
import { Post } from './post.entity';

@Injectable()
export class PostService {
  constructor(
    @InjectRepository(Post)
    private readonly postRepository: Repository<Post>,
  ) {}

  public async getPosts(): Promise<Post[]> {
    return this.postRepository.find();
  }

  public async getPostById(id: string): Promise<Post> {
    const post = this.postRepository.findOne({ where: { id: id } });
    if (!post) {
      throw new NotFoundException(`Post with id ${id} not found`);
    }
    return post;
  }

  public async createPost(postDto: CreatePostDto): Promise<Post> {
    const post = this.postRepository.create(postDto);
    await this.postRepository.save(post);
    return post;
  }
  public async updatePost(id: string, postDto: UpdatePostDto): Promise<Post> {
    const post = await this.postRepository.findOne({ where: { id: id } });
    if (!post) {
      throw new NotFoundException(`Post with id ${post.id} not found`);
    }
    const updated = Object.assign(post, postDto);
    updated.updatedAt = Date.now();
    await this.postRepository.save(updated);
    return updated;
  }

  public async deletePost(id: string): Promise<void> {
    await this.postRepository.delete(id);
  }
}

PostController will be not changed.

Run server & test api endpoints with postman

Documentation with Swagger/Open API

To better check available you api endpoint, I think it's usefull to setup Swagger documentation as soon as possible.

Check swagger.io & Nest Open api for more information.

Installation

$ yarn add -D @nestjs/swagger swagger-ui-express

Setup swagger Create swagger constants: src/common/config/swagger/swagger.contants.ts

//swagger.constants.ts
export const SWAGGER_API_ROOT = 'api/docs';
export const SWAGGER_API_NAME = 'Simple API';
export const SWAGGER_API_DESCRIPTION = 'Simple API Description';
export const SWAGGER_API_CURRENT_VERSION = '1.0';

And src/common/config/swagger/index.ts for swagger config

import { INestApplication } from '@nestjs/common';
import { SwaggerModule, DocumentBuilder } from '@nestjs/swagger';

import {
  SWAGGER_API_CURRENT_VERSION,
  SWAGGER_API_DESCRIPTION,
  SWAGGER_API_NAME,
  SWAGGER_API_ROOT,
} from './swagger.constants';

export const setupSwagger = (app: INestApplication) => {
  const options = new DocumentBuilder()
    .setTitle(SWAGGER_API_NAME)
    .setDescription(SWAGGER_API_DESCRIPTION)
    .setVersion(SWAGGER_API_CURRENT_VERSION)
    .addBearerAuth()
    .build();

  const document = SwaggerModule.createDocument(app, options);
  SwaggerModule.setup(SWAGGER_API_ROOT, app, document);
};

Update swagger config in main.ts file

// main.ts
async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  app.enableCors();
  app.useGlobalPipes(new ValidationPipe());
  // attaches cookies to request object
  app.use(cookieParser());
  // applies security hardening settings. using defaults: https://www.npmjs.com/package/helmet
  app.use(helmet());
  app.setGlobalPrefix('api');
+ setupSwagger(app);
  const port = process.env.SERVER_PORT;
  await app.listen(port, () => {
    console.log(`Server is running at http://localhost:${port}/`);
  });
}
bootstrap();

Update swagger tag for controller Using @ApiTags('route name') class decorator in controller file:

@ApiTags('Root')
@Controller()
export class AppController {
...
}

@ApiTags('Post')
@Controller('posts')
export class PostController {
...
}

Run server and check api docs at route: /api/docs:

3. Auth

Click to expand section

Check the code at branch 3-auth

Create authentication with bcrypt, passport Nestjs, Jwt & cookies

Check Nest security for more information.

User

To use authentication, first of all, wee need to have User table.

Create UserEntity with Typeorm: src/modules/user/user.entity.ts

//user.entity.ts
import { Entity, Column, PrimaryGeneratedColumn } from 'typeorm';

@Entity()
export class User {
  @PrimaryGeneratedColumn('uuid')
  id: string;

  @Column()
  name: string;

  @Column({ unique: true })
  email: string;

  @Column()
  password: string;
}

User service: src/modules/user/user.service.ts With the demo purpose, we don't need to create UserController (to have route update, delete ... for user). In UserService, we just create some simple helper methods to use in AuthService.

import { RegisterUserDto } from '@modules/auth/dto';
import { Injectable } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository } from 'typeorm';
import { User } from './user.entity';

@Injectable()
export class UserService {
  constructor(
    @InjectRepository(User)
    private readonly userRepository: Repository<User>,
  ) {}

  public async getUsers(): Promise<User[]> {
    return await this.userRepository.find();
  }
  public async getUserById(id: string): Promise<User> {
    return await this.userRepository.findOne({ where: { id: id } });
  }
  public async getUserByEmail(email: string): Promise<User> {
    return await this.userRepository.findOne({ where: { email: email } });
  }
  public async create(userDto: RegisterUserDto): Promise<User> {
    const user = this.userRepository.create(userDto);
    await this.userRepository.save(user);
    return user;
  }
}

And update UserModule: src/modules/user/user.module.ts

import { Module } from '@nestjs/common';
import { TypeOrmModule } from '@nestjs/typeorm';
import { User } from './user.entity';
import { UserService } from './user.service';

@Module({
  imports: [TypeOrmModule.forFeature([User])],
  providers: [UserService],
  exports: [UserService],
})
export class UserModule {}

Note: TypeOrmModule.forFeature([User]) allows to use UserRepository of TypeOrm in all User providers files.

Don't forget import UserModule in AppModule

Auth

The easiest way protect auth with Nest app is using passport & Json web token strategy. The docs of Nest well explain this part in details. Check Nest Authentication

There are two strategies:

Passport strategy: We will use passport-local to authenticate when user login
Json web token strategy: using in all other protected routes

When an user login, it will verify email (or username) & password. If it match, an user logged is assigned in Request. And we will save information of this user in cookie by the json token code. This json web token will be verified in each request in each route that we implements Jwt guards.

Ok, that's is a little bit theory. Now, we will start to code to better understand it.

Installation

For this part, we need to install packages:

bcrypt: For hashing password
passport-jwt: passport strategy with json web token
@nestjs/jwt & passport-jwt to use feature JWT of Nestjs

cookie-parser: to parse cookie

$ yarn add @nestjs/jwt @nestjs/passport passport-jwt cookie-parser bcrypt
$ yarn add -D @types/bcrypt @types/cookie-parser @types/passport-jwt

Auth service

Update middleware : app.use(cookieParser()); in main.ts file.

Create auth.service.ts file in src/modules/auth

// auth.service.ts
import {
  BadRequestException,
  ConflictException,
  HttpException,
  HttpStatus,
  Injectable,
} from '@nestjs/common';
import * as bcrypt from 'bcrypt';
import { JwtService } from '@nestjs/jwt';
import { IPayloadJwt } from './auth.interface';
import { RegisterUserDto } from './dto';
import { UserService } from '@modules/user/user.service';

@Injectable()
export class AuthService {
  constructor(
    private readonly userService: UserService,
    private readonly jwtService: JwtService,
  ) {}

  public async validateUser(email: string, password: string) {
    const user = await this.userService.getUserByEmail(email);
    if (user) {
      const isMatch = await bcrypt.compare(password, user.password);
      if (isMatch) {
        return user;
      }
    }
    throw new BadRequestException('Invalids credentials');
  }

  public async register(registerDto: RegisterUserDto) {
    const userCheck = await this.userService.getUserByEmail(registerDto.email);
    if (userCheck) {
      throw new ConflictException(
        `User with email: ${registerDto.email} already exists`,
      );
    }
    const salt = await bcrypt.genSalt(10);
    const hashPassword = await bcrypt.hash(registerDto.password, salt);

    try {
      const user = await this.userService.create({
        ...registerDto,
        password: hashPassword,
      });
      return user;
    } catch (error) {
      throw new HttpException(error.message, HttpStatus.INTERNAL_SERVER_ERROR);
    }
  }

  public getCookieWithToken(payload: IPayloadJwt) {
    const token = this.jwtService.sign(payload);
    return `Authorization=${token};HttpOnly;Path=/;Max-Age=${process.env.JWT_EXPIRATION_TIME}`;
  }
  public clearCookie() {
    return `Authorization=;HttpOnly;Path=/;Max-Age=0`;
  }
}

In AuthService, we inject UserService and JwtService (provide by @nestjs/jwt)
register method: using when an user want to register new account
validateUser method: Use to verify email & password given by user request. We will use this method in local-password strategy too.
getCookie methods: using to generate cookies with jwt & clear it when user logged out.

Create auth strategies

Create Passport local strategy Create local.strategy.ts in src/modules/auth/strategies:

// local.strategy.ts
import { User } from '@modules/user/user.entity';
import { Injectable } from '@nestjs/common';
import { PassportStrategy } from '@nestjs/passport';
import { Strategy } from 'passport-local';
import { AuthService } from '../auth.service';

@Injectable()
export class LocalStrategy extends PassportStrategy(Strategy) {
  constructor(private _authService: AuthService) {
    super({ usernameField: 'email' });
  }

  public async validate(email: string, password: string): Promise<User> {
    const user = await this._authService.validateUser(email, password);
    return user;
  }
}

This stragety is very simple. We create class LocalStrategy extends from PassportStrategy of @Nestjs/passport module.

We use super({ usernameField: 'email' });: that means we use the field 'email' to verify account. By default with super() is 'username'.

In this class, we need have an method validate. The passport strategy of Nestjs will trigger this method automatically for Passport guard.

Note: don't for get use @Injectable() to make this class as a custom providers to import or export in Auth module.

Create Jwt strategy: jwt.strategy.ts

// jwt.strategy.ts
import { IPayloadJwt } from '../auth.interface';
import { Injectable } from '@nestjs/common';
import { ExtractJwt, Strategy } from 'passport-jwt';
import { PassportStrategy } from '@nestjs/passport';
import { UserService } from '@modules/user/user.service';
import { Request } from 'express';

@Injectable()
export class JwtStrategy extends PassportStrategy(Strategy) {
  constructor(private readonly userService: UserService) {
    super({
      jwtFromRequest: ExtractJwt.fromExtractors([
        (req: Request) => {
          return req?.cookies?.Authorization;
        },
      ]),
      ignoreExpiration: false,
      secretOrKey: process.env.JWT_SECRET,
    });
  }
  public async validate(payload: IPayloadJwt) {
    const user = await this.userService.getUserByEmail(payload.email);
    return user;
  }
}

Principe of Jwt strategy is the same with local passport strategy. But in the implement super() of parent class, we need setup some config for jwt & cookies.
JWT_SECRET: variable environment setup in .env file

If you don't want to you extract cookie, just extract with Bearer authentication header:

super({
  jwtFromRequest: ExtractJwt.fromAuthHeaderAsBearerToken(),
  ignoreExpiration: false,
  secretOrKey: process.env.JWT_SECRET,
});

Create guards files to indicate which guard auth we will use for routing

local-auth.guard.ts

// local.strategy.ts
import { Injectable } from '@nestjs/common';
import { AuthGuard } from '@nestjs/passport';

@Injectable()
export class LocalAuthGuard extends AuthGuard('local') {}

jwt-auth.guard.ts

// jwt.guard.ts
import { Injectable } from '@nestjs/common';
import { AuthGuard } from '@nestjs/passport';

@Injectable()
export class JwtAuthGuard extends AuthGuard('jwt') {}

Auth controller

Ok, now we will update auth guard in our routes

Create AuthController: src/modules/auth/auth.controller.ts

// auth.controller
import { IRequestWithUser } from '@common/interfaces/http.interface';
import {
  Body,
  Controller,
  Get,
  Post,
  Req,
  Res,
  UseGuards,
} from '@nestjs/common';
import { IPayloadJwt } from './auth.interface';
import { AuthService } from './auth.service';
import { RegisterUserDto } from './dto';
import { LocalAuthGuard } from './guards/local-auth.guard';
import { Response } from 'express';
import { JwtAuthGuard } from './guards/jwt-auth.guard';
import { ApiTags } from '@nestjs/swagger';

@ApiTags('Auth')
@Controller('auth')
export class AuthController {
  constructor(private readonly authService: AuthService) {}

  @Post()
  public async register(@Body() registerDto: RegisterUserDto) {
    const user = await this.authService.register(registerDto);
    // eslint-disable-next-line @typescript-eslint/no-unused-vars
    const { password, ...rest } = user;
    return rest;
  }

  @Post('login')
  @UseGuards(LocalAuthGuard)
  public async login(@Req() req: IRequestWithUser, @Res() res: Response) {
    const { user } = req;
    const payload: IPayloadJwt = {
      userId: user.id,
      email: user.email,
    };
    const cookie = this.authService.getCookieWithToken(payload);
    res.setHeader('Set-Cookie', cookie);
    // eslint-disable-next-line @typescript-eslint/no-unused-vars
    const { password, ...rest } = user;
    return res.send(rest);
  }

  @Get()
  @UseGuards(JwtAuthGuard)
  public getAuthenticatedUser(@Req() req: IRequestWithUser) {
    // eslint-disable-next-line @typescript-eslint/no-unused-vars
    const { password, ...rest } = req.user;
    return rest;
  }

  @Post('logout')
  @UseGuards(JwtAuthGuard)
  public async logout(@Res() res: Response) {
    res.setHeader('Set-Cookie', this.authService.clearCookie());
    return res.sendStatus(200);
  }
}

@UseGuards(LocalAuthGuard): for local strategy --> using for login
@UseGuards(JwtAuthGuard): for jwt strategy --> using to protect our routes

When use login, we need to set cookie with new json web token.

Update also auth Guards in Postcontroller

Complete authentication part

Create auth.module.ts

import { Module } from '@nestjs/common';
import { AuthService } from './auth.service';
import { LocalStrategy } from './strategies/local.strategy';
import { PassportModule } from '@nestjs/passport';
import { UserModule } from '@modules/user/user.module';
import { JwtModule } from '@nestjs/jwt';
import { JwtStrategy } from './strategies/jwt.strategy';
import { AuthController } from './auth.controller';
@Module({
  imports: [
    UserModule,
    PassportModule,
    JwtModule.register({
      secret: process.env.JWT_SECRET,
      signOptions: { expiresIn: process.env.JWT_EXPIRE_TIME },
    }),
  ],
  providers: [AuthService, LocalStrategy, JwtStrategy],
  exports: [AuthService],
  controllers: [AuthController],
})
export class AuthModule {}

Import AuthModule in AppModule and run server to test

Note: To test cookie with postman: If the project works properly, when you logged successfully, a cookie will be created automatically.

But if you want to use this cookie to test other protected routes, you need to copie that and add it to header with the key: "Cookie" --> value: value of cookie copied

See the photo to better understand.

4. Error handling

Click to expand section

Check the code at branch 4-error-handling

Exception filter

Nest use built-in exception layer which is responsible for processing all unhandled exceptions across an application.

Check Nest exception filter for information details.

Format of an exception:

{
  "statusCode": number,
  "message": string
}

Throw standard exception in Nest Here is some examples using Exception filter in app:

const post = await this.postRepository.findOne({ where: { id: id } });
  if (!post) {
    throw new NotFoundException(`Post with id ${post.id} not found`);
  }

const user = await this.userService.getUserByEmail(email);
  if (user) {
    const isMatch = await bcrypt.compare(password, user.password);
    if (isMatch) {
      return user;
    }
  }
  throw new BadRequestException('Invalids credentials');

const userCheck = await this.userService.getUserByEmail(registerDto.email);
  if (userCheck) {
    throw new ConflictException(
      `User with email: ${registerDto.email} already exists`,
    );
  }

} catch (error) {
    throw new HttpException(error.message, HttpStatus.INTERNAL_SERVER_ERROR);
  }

Create custom exception: Logger exception

ex: Forbidden.exception.ts

export class ForbiddenException extends HttpException {
  constructor() {
    super('Forbidden', HttpStatus.FORBIDDEN);
  }
}

Check more Nest exception filter.

Validation

Nest provides several pipes available right out-of-the-box:

ValidationPipe
ParseIntPipe
ParseBoolPipe
ParseArrayPipe
ParseUUIDPipe

The ValidationPipe makes use of the powerful class-validator package and its declarative validation decorators.

The ValidationPipe provides a convenient approach to enforce validation rules for all incoming client payloads, where the specific rules are declared with simple annotations in local class/DTO declarations in each module.

We will use auto-validation of Nest:

Setup in main.ts

// main.ts
async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  app.useGlobalPipes(new ValidationPipe());
  ...
}
bootstrap();

Install indispensable package dependency to make it works:
- Class-validator
- Class-transformer
```
$ yarn add class-transformer class-validator
```

Using class-validator We will use this package to make sûre that we have good data for body request (DTO) & for entity data before save to database.

Example using validation in user.entity.ts

// user.entity.ts
import { Entity, Column, PrimaryGeneratedColumn } from 'typeorm';
import { IsDate, IsEmail, Min } from 'class-validator';
import moment from 'moment';

@Entity()
export class User {
  @PrimaryGeneratedColumn('uuid')
  id: string;

  @Column()
  name: string;

  @Column({ unique: true })
  @IsEmail()
  email: string;

  @Column()
  @Min(0)
  password: string;

  @Column({
    type: Date,
    default: moment(new Date()).format('YYYY-MM-DD HH:ss'),
    nullable: true,
  })
  @IsDate()
  createdAt: Date;

  @Column({
    type: Date,
    default: moment(new Date()).format('YYYY-MM-DD HH:ss'),
    nullable: true,
  })
  @IsDate()
  updatedAt: Date;
}

Example in create-post.dto.ts

import { IsString } from 'class-validator';

export class CreatePostDto {
  @IsString()
  title: string;

  @IsString()
  content: string;
}

Check more Doc class-validator for advanced validation.

5. Serialization

Click to expand section

Check the code at branch 5-serialization

If you remember, in previous part, when we want to return user from request, we need to exclude password field with destructuring Javascript method.

But in the real project, we will have many secret field, we will don't do like that. Normally, we can create data transfer object and create the mapper method from real object to dto object. Then it will return a safe data for client.

The Nest framework make use of powerful of class-transformer, it helps us to resolve this problem more simpler. Check out Nest serialization

Now, we see how to implement Nest serialization:

Exclude option

Using Exclude in entities

User Entity:

// user.entity.ts
import { Entity, Column, PrimaryGeneratedColumn } from 'typeorm';
import { IsDate, IsEmail, Min } from 'class-validator';
import moment from 'moment';
+ import { Exclude } from 'class-transformer';

@Entity()
export class User {
  @Column()
  @Min(0)
+   @Exclude()
  password: string;

Using ClassSerializerInterceptor in controller

// auth.controller.ts
@Controller('auth')
@UseInterceptors(ClassSerializerInterceptor)
export class AuthController {
...
}

Or we can set global for ClassSerializerInterceptor

// main.ts
async function bootstrap() {
const app = await NestFactory.create(AppModule);
app.enableCors();
app.useGlobalPipes(new ValidationPipe({ skipMissingProperties: true }));
+ app.useGlobalInterceptors(new ClassSerializerInterceptor(app.get(Reflector)));
...
}

Expose option

@SerializeOptions() By default, all properties of our entities are exposed. We can change this strategy by providing additional options to the class-transformer.

@Controller('auth')
@SerializeOptions({
  strategy: 'excludeAll'
})
export class AuthenticationController

And user.entity.ts

import { Column, Entity, PrimaryGeneratedColumn } from 'typeorm';
import { Expose } from 'class-transformer';

@Entity()
class User {
  @PrimaryGeneratedColumn('uuid')
  public id?: string;

  @Column({ unique: true })
  @Expose()
  public email: string;

  @Column()
  @Expose()
  public name: string;

  @Column()
  public password: string;
}

export default User;

Example results: First result before use option expose:

{
  "name": "user1",
  "email": "user1@gmail.com",
  "passport": "£ùdsql!-$fhkqpsdfhosdhfsdhf$+o~qsd*46dfqsdf"
}

---> Result after expose All:

{
  "name": "user1",
  "email": "user1@gmail.com",
}

Nullable features of class-transformer The @SerializeOptions() matchs the options that you can provide for the classToPlain method in the class-transformer.

For example: before you use @Column({nullable: true}), but with NestJs & Class-transformer, you can make like you code typescript directly:
```
@Entity()
class Post {
  // ...

  @Column({ nullable: true })
  public category?: string;
}
```
Or if you don't want to return to response when this field null with @Transform of class-transformer.
```
@Column({ nullable: true })
 @Transform((value) => {
  if (value) {
    return value;
  }
})
public category?: string;
```

Issues with using @Res() decorator

In the previous part, we have used the @Res() decorator to access the Express Response object.

Previous method login in AuthController

// auth.controller.ts
@Post('login')
  @UseGuards(LocalAuthGuard)
  public async login(@Req() req: IRequestWithUser, @Res() res: Response) {
    const { user } = req;
    const payload: IPayloadJwt = {
      userId: user.id,
      email: user.email,
    };
    const cookie = this.authService.getCookieWithToken(payload);
    res.setHeader('Set-Cookie', cookie);
    // eslint-disable-next-line @typescript-eslint/no-unused-vars
    const { password, ...rest } = user;
    return res.send(rest);
  }

Using the @Res() decorator strips us from some advantages of using NestJS. Unfortunately, it interferes with the ClassSerializerInterceptor. To prevent that, we can follow some advice from the creator of NestJS. If we use the request.res object instead of the @Res() decorator, we don’t put NestJS into the express-specific mode.

Solution:

// auth.controller.ts
@Post('login')
@UseGuards(LocalAuthGuard)
public async login(@Req() req: IRequestWithUser) {
  const { user } = req;
  const payload: IPayloadJwt = {
    userId: user.id,
    email: user.email,
  };
  const cookie = this.authService.getCookieWithToken(payload);
  req.res.setHeader('Set-Cookie', cookie);
  return user;
}

6. Database relationship

Click to expand section

Check the code at branch 6-db-relationship

About database relationship of Typeorm, check:

Typeorm one to one relations
Typeorm relations
Typeorm relations faq
Typeorm relational query builder

Missing docs for this part. Working in progress....

7. Testing

Click to expand section

Check the code at branch 7-testing

Unit testing
Integration testing

Run test: yarn test:

Missing docs for this part. Working in progress....

8. End to end testing (e2e)

Click to expand section

Check the code at branch 8-e2e-testing

Check more information at Nestjs end to end testing

Introduction

Unlike unit testings (individual modules, methods or class test), end to end testing focus on the integrity of the application. We will test the entire application from start to finish, just like a regular user would, to see if it behaves as expected.

Nest makes it easy to use the Supertest library to simulate HTTP requests.

When we create project with Nest CLI, if you remember, there is always an folder test was create in the root project. In this folder, we we save our file end-to-end(e2e) testing.

Test root folder

In the test root folder (<rootDir>/test), we have 2 files:

jest-e2e.json: Config for e2e test jest-e2e.json generated from Nest ClI:

{
  "moduleFileExtensions": ["js", "json", "ts"],
  "rootDir": ".",
  "testEnvironment": "node",
  "testRegex": ".e2e-spec.ts$",
  "transform": {
    "^.+\\.(t|j)s$": "ts-jest"
  }
}

app.e2e-spec.ts: File test for app module. We can create each files e2e test for each controller. But in our demo, we don't have many controller, to simplify, we can put all the test code of all controllers in this app.e2e-spec.ts file.

// test/app.e2e-spec.ts
import { Test, TestingModule } from '@nestjs/testing';
import { INestApplication } from '@nestjs/common';
import * as request from 'supertest';
import { AppModule } from '../src/app.module';

describe('AppController (e2e)', () => {
  let app: INestApplication;

  beforeEach(async () => {
    const moduleFixture: TestingModule = await Test.createTestingModule({
      imports: [AppModule],
    }).compile();

    app = moduleFixture.createNestApplication();
    await app.init();
  });

  it('/ (GET)', () => {
    return request(app.getHttpServer())
      .get('/')
      .expect(200)
      .expect('Hello World!');
  });
});

For running e2e test, Nest has already setup it in package.json file: yarn test:e2e

Note: For name of e2e test file, make sure you have suffix .e2e-spec.ts, because, if you look in jest-e2e.json, it matches only with this suffix (Or you can change as you want, but you need match them together)

Develop

Firstly, we will modify a little bit config in jest-e2e.json to work properly with our project:

jest-e2e.json file:

{
  "moduleFileExtensions": ["js", "json", "ts"],
  "rootDir": "../",
  "testEnvironment": "node",
  "testRegex": ".e2e-spec.ts$",
  "transform": {
    "^.+\\.(t|j)s$": "ts-jest"
  },
  "moduleNameMapper": {
    "@common/(.*)": "<rootDir>/src/common/$1",
    "@modules/(.*)": "<rootDir>/src/modules/$1",
    "@app/(.*)": "<rootDir>/src/app/$1"
  }
}

Now we will start make e2e test for each module.

AppModule As AppModule has only an root route, and it return 'Hello world' when an user request. So the e2e test we will be like this:

import { Test, TestingModule } from '@nestjs/testing';
import { INestApplication } from '@nestjs/common';
import request from 'supertest';
import { AppModule } from '../src/app/app.module';

describe('AppController (e2e)', () => {
  let app: INestApplication;

  beforeAll(async () => {
    const moduleFixture: TestingModule = await Test.createTestingModule({
      imports: [AppModule],
    }).compile();

    app = moduleFixture.createNestApplication();
    // app.useGlobalPipes(new ValidationPipe({ skipMissingProperties: true }));
    // app.useGlobalInterceptors(new ClassSerializerInterceptor(app.get(Reflector)));
    await app.init();
  });

  afterAll(async () => {
    await app.close();
  });

  /* Root */
  describe('AppModule', () => {
    it('(GET) /', () => {
      return request(app.getHttpServer())
        .get('/')
        .expect(200)
        .expect('Hello World!');
    });
  });

});

When user request to root (/), we will need request successfully, it will return with status code = 200 and body = 'Hello World!')

Note: Here is just simple setup for app initialization, but you can setup all necessary configurations for your app as in main.ts file for app too.

For example: app.useGlobalPipes(...), app.useGlobalInterceptors(...), app.enableCors()...et...

Other modules

The end to end testing focus on user story, so it's better you make the test follow this approach. For example: When you go to website:

You will request root route first
After you create an account
You check login route
After login (setHeader with cookie), now we have been authenticated
Check the public routes as get posts, get categories
Test actions in private route as createPost, updatePost; deletePost...
We can create also another file test for another approach with non authenticate and check authorization access route

Example for test e2e login:

  /* Auth */
  describe('AuthModule', () => {
    describe('(POST) /auth/login', () => {
      it('Should login successfully', async () => {
        const user = {
          email: 'user1@gmail.com',
          password: '1234567',
        };
        const data = await request(app.getHttpServer())
          .post('/auth/login')
          .send(user)
          .expect(201);
        expect(data.body).toBeDefined();
      });
    });
  });

In this part, there will have much code to do. I will come back to update them.

--> Work in progress ...

9.1 Web service AWS S3

Click to expand section

Check the code at branch 9-aws-s3

Amazon S3 has a simple web services interface that you can use to store and retrieve any amount of data, at any time, from anywhere on the web. It gives any developer access to the same highly scalable, reliable, fast, inexpensive data storage infrastructure that Amazon uses to run its own global network of web sites. The service aims to maximize benefits of scale and to pass those benefits on to developers.

Create IAM user

To use AWS service S3, make sure you have an account AWS.

Each service of AWS need an Identity and Access Management (IAM)

After create an user IAM for S3 service, you will receive an Access key ID and an Secret access key. We will add them in .env file to connect to AWS service through our API.

We also need to choose one of the available regions. For example, my regions is: eu-west-3 for Europe France

Create AWS S3 bucket

In Amazon S3 data is organized in buckets. We can have multiple buckets with different settings.

Let’s open the Amazon S3 panel and create a bucket. Please note that the name of the bucket must be unique.

We can set up our bucket to contain public files. All files that we upload to this bucket will be publicly available. We might use it to manage files such as avatars.

Update variables enviroments

Now start to setup connection for AWS in our API

.env file

# ...
AWS_REGION=eu-west-3
AWS_ACCESS_KEY_ID=*******
AWS_SECRET_ACCESS_KEY=*******
AWS_PUBLIC_BUCKET_NAME=nestjs-flow-public-bucket

Update types in src/common/types/node.d.ts

// node.d.ts
  declare namespace NodeJS {
  interface ProcessEnv {
    readonly NODE_ENV: 'development' | 'production' | 'test';
    readonly SERVER_PORT: string;
    readonly TYPEORM_CONNECTION: string;
    readonly TYPEORM_HOST: string;
    readonly TYPEORM_USERNAME: string;
    readonly TYPEORM_PASSWORD: string;
    readonly TYPEORM_DATABASE: string;
    readonly TYPEORM_PORT: string;
    readonly TYPEORM_LOGGING: string;
    readonly TYPEORM_ENTITIES: string;
    readonly TYPEORM_MIGRATIONS: string;
    readonly ROUTE_GLOBAL_PREFIX: string;
    readonly JWT_SECRET: string;
    readonly TWO_FACTOR_AUTHENTICATION_APP_NAME: string;
    readonly JWT_EXPIRATION_TIME: string;
    readonly AWS_REGION: string;
    readonly AWS_ACCESS_KEY_ID: string;
    readonly AWS_SECRET_ACCESS_KEY: string;
    readonly AWS_PUBLIC_BUCKET_NAME: string;
  }
}

To connect with AWS service, we need to install aws-sdk-js
```
$ yarn add aws-sdk
$ yarn add -D @types/aws-sdk
```

Create FileModule

We will use AWS S3 to upload avatar of user.

Create src/modules/files/public-file.entity.ts

// public-file.entity.ts
import { Column, Entity, OneToOne, PrimaryGeneratedColumn } from 'typeorm';

@Entity()
export class PublicFile {
  @PrimaryGeneratedColumn('uuid')
  public id: string;

  @Column({ unique: true })
  public key: string;

  @Column()
  public url: string;
}

Create src/modules/files/services/s3.service.ts

// s3.service.ts
import { Injectable } from '@nestjs/common';
import { S3 } from 'aws-sdk';
import { v4 as uuid } from 'uuid';
import { DeletePublicFileDto } from '../dto';

@Injectable()
export class S3Service {
  private s3: S3;
  private bucketName: string;
  constructor() {
    this.s3 = new S3();
    this.bucketName = process.env.AWS_PUBLIC_BUCKET_NAME;
  }
  public async uploadResult(
    dataBuffer: Buffer,
    filename: string,
  ): Promise<S3.ManagedUpload.SendData> {
    const uploadResult = await this.s3
      .upload({
        Bucket: this.bucketName,
        Body: dataBuffer,
        Key: `${uuid()}-${filename}`,
      })
      .promise();
    return uploadResult;
  }

  public async deleteFile(fileDto: DeletePublicFileDto) {
    await this.s3
      .deleteObject({
        Bucket: process.env.AWS_PUBLIC_BUCKET_NAME,
        Key: fileDto.key,
      })
      .promise();
    return { deleted: true };
  }
}

Why we need an file dependent for s3Service? --> We use the dependents service for easier in test.

Create src/modules/files/services/files.service.ts

// files.service.ts
import {
  HttpException,
  HttpStatus,
  Injectable,
  NotFoundException,
} from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { PublicFileRepository } from '../public-file.repository';

import { CreatePublicFileDto, DeletePublicFileDto } from '../dto';
import { S3Service } from './s3.service';
import { PublicFile } from '../public-file.entity';

@Injectable()
export class FilesService {
  constructor(
    @InjectRepository(PublicFileRepository)
    private readonly publicFileRepo: PublicFileRepository,
    private readonly s3Service: S3Service,
  ) {}

  public async getFileById(id: string) {
    try {
      const file = this.publicFileRepo.getFileById(id);
      if (!file) {
        throw new NotFoundException('File not found');
      }
      return file;
    } catch (error) {
      if (error.status === HttpStatus.NOT_FOUND) {
        throw error;
      }
      throw new HttpException(error.message, HttpStatus.NOT_FOUND);
    }
  }

  public async uploadPublicFile(dataBuffer: Buffer, filename: string) {
    try {
      const uploadResult = await this.s3Service.uploadResult(
        dataBuffer,
        filename,
      );
      const fileDto: CreatePublicFileDto = {
        key: uploadResult.Key,
        url: uploadResult.Location,
      };
      const newFile = await this.publicFileRepo.createPublicFile(fileDto);
      return newFile;
    } catch (error) {
      throw new HttpException(error.message, HttpStatus.INTERNAL_SERVER_ERROR);
    }
  }

  public async deletePublicFile(fileId: string) {
    try {
      const file = await this.publicFileRepo.getFileById(fileId);
      if (!file) {
        throw new NotFoundException('File not found');
      }
      const fileDto: DeletePublicFileDto = {
        key: file.key,
      };
      await this.s3Service.deleteFile(fileDto);

      return await this.publicFileRepo.deleteFile(fileId);
    } catch (error) {
      if (error.status === HttpStatus.NOT_FOUND) {
        throw error;
      } else {
        throw new HttpException(
          error.message,
          HttpStatus.INTERNAL_SERVER_ERROR,
        );
      }
    }
  }
}

And we package all these file to FileModule

Using PublicFile Entity and FileService in UserModule to create user avatar.

User Entity:

// user.entity.ts
// ....
@JoinColumn()
@OneToOne(() => PublicFile, {
  eager: true,
  nullable: true,
  onDelete: 'CASCADE',
})
public avatar: PublicFile;

@BeforeUpdate()
updateTimestamp() {
  this.updatedAt = new Date();
}
// ...

Create methods upload and delete avatar

In user.service.ts: create method: addAvatar & deleteAvatar

// user.service.ts

 public async addAvatar(
    userId: string,
    imageBuffer: Buffer,
    filename: string,
  ) {
    try {
      const user = await this.userRepository.getUserById(userId);
      if (user.avatar) {
        await this.userRepository.updateAvatar(user, {
          avatar: null,
        });
        await this.filesService.deletePublicFile(user.avatar.id);
      }
      const avatar = await this.filesService.uploadPublicFile(
        imageBuffer,
        filename,
      );
      await this.userRepository.updateAvatar(user, { avatar: avatar });
      return avatar;
    } catch (error) {
      throw new HttpException(error.message, HttpStatus.INTERNAL_SERVER_ERROR);
    }
  }

  public async deleteAvatar(userId: string) {
    try {
      const user = await this.userRepository.getUserById(userId);
      const fileId = user.avatar?.id;
      if (fileId) {
        await this.userRepository.updateAvatar(user, {
          avatar: null,
        });
        await this.filesService.deletePublicFile(fileId);
      }
    } catch (error) {
      throw new HttpException(error.message, HttpStatus.INTERNAL_SERVER_ERROR);
    }
  }

Then create 2 routes for 2 this methods in UserController

// user.controller.ts
@Post('avatar')
@UseGuards(JwtAuthGuard)
@UseInterceptors(FileInterceptor('file'))
public async addAvatar(@Req() req: IRequestWithUser, @UploadedFile() file) {
  const { user } = req;
  return await this.userService.addAvatar(
    user.id,
    file.buffer,
    file.originalname,
  );
}

@Delete('avatar')
@UseGuards(JwtAuthGuard)
public async deleteAvatar(@Req() req: IRequestWithUser) {
  return await this.userService.deleteAvatar(req.user.id);
}

When all things done, you can start to test upload image to AWS through your API with Postman

That's is all the setup to use Public bucket service of AWS.

9.2 Private bucket AWS

Click to expand section

Check the code at branch 9-aws-private-files

There is quite a bit more to Amazon S3 than storing public files. In this article, we look into how we can manage private files. To do so, we learn how to set up a proper private Amazon S3 bucket and how to upload and access files. We use streams and generate presigned URLs with an expiration time.

Setting up AWS S3

We will create new bucket as we did in the previous part. But this time, we will make private bucket. That's means we will block all public access for bucket (feature of AWS S3)

The first thing to do is to create a new bucket.

This time, we intend to restrict access to the files we upload. Every time we want our users to be able to access a file, they will need to do it through our API.

The IAM user that we’ve created in the previous part of this series has access to all our buckets. Therefore, all we need to do to start using it is to add the name of the bucket to our environment variables.

Update .env file

# ...
AWS_PRIVATE_BUCKET_NAME=nestjs-series-private-bucket

Update node.d.ts

// node.d.ts
declare namespace NodeJS {
  interface ProcessEnv {
   // ...
    readonly AWS_PRIVATE_BUCKET_NAME: string;
  }
}

Update FileModule for Private bucket

Create privateFiles entity: src/modules/files/private-file.entity.ts

// private-file.entity.ts

import { User } from '@modules/user/user.entity';
import { Column, Entity, ManyToOne, PrimaryGeneratedColumn } from 'typeorm';

@Entity()
export class PrivateFile {
  @PrimaryGeneratedColumn('uuid')
  public id: string;

  @Column({ unique: true })
  public key: string;

  @ManyToOne(() => User, (owner: User) => owner.files)
  public owner: User;
}

Using PrivateFile in UserEntity

// user.entity.ts
// ...
import { PublicFile } from '@modules/files/public-file.entity';
import { PrivateFile } from '@modules/files/private-file.entity';

@Entity()
export class User {
  // ...

  @OneToMany(
    () => PrivateFile,
    (file: PrivateFile) => file.owner
  )
  public files: PrivateFile[];
}

Create PrivateFileService: src/modules/files/services/private-files.service.ts

// private.files.service.ts

import { HttpException, HttpStatus, Injectable } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { CreatePrivateFileDto } from '../dto/create-private-file.dto';
import { PrivateFileRepository } from '../repositories/private-file.repository';
import { S3Service } from './s3.service';

@Injectable()
export class PrivateFileService {
  constructor(
    @InjectRepository(PrivateFileRepository)
    private privateFileRepo: PrivateFileRepository,
    private s3Service: S3Service,
  ) {}
  //...

 public async uploadPrivateFile(
    ownerId: string,
    dataBuffer: Buffer,
    filename: string,
  ) {
    try {
      const uploadResult = await this.s3PrivateFileService.uploadResult(
        dataBuffer,
        filename,
      );
      const fileDto: CreatePrivateFileDto = {
        key: uploadResult.Key,
        owner: {
          id: ownerId,
        },
      };
      const newFile = await this.privateFileRepo.createPrivateFile(fileDto);
      return newFile;
    } catch (error) {
      throw new HttpException(error.message, HttpStatus.INTERNAL_SERVER_ERROR);
    }
  }

  public async uploadMultiplePrivateFile(
    ownerId: string,
    uploadFiles: UploadFileDto[],
  ) {
    try {
      const resultFiles = [];
      for (const upload of uploadFiles) {
        const uploadResult = await this.s3PrivateFileService.uploadResult(
          upload.dataBuffer,
          upload.filename,
        );
        const fileDto: CreatePrivateFileDto = {
          key: uploadResult.Key,
          owner: {
            id: ownerId,
          },
        };
        const newFile = await this.privateFileRepo.createPrivateFile(fileDto);
        resultFiles.push(newFile);
      }

      return resultFiles;
    } catch (error) {
      throw new HttpException(error.message, HttpStatus.INTERNAL_SERVER_ERROR);
    }
  }

  public async deletePrivateFile(fileId: string) {
    const file = await this.getFileById(fileId);
    try {
      const fileDto: DeletePrivateFileDto = {
        key: file.key,
      };
      await this.s3PrivateFileService.deleteFile(fileDto);

      return await this.privateFileRepo.deleteFile(fileId);
    } catch (error) {
      throw new HttpException(error.message, HttpStatus.INTERNAL_SERVER_ERROR);
    }
  }
}

Update UserService

// user.service.ts
// ...
@Injectable()
export class UserService {
  constructor(
    @InjectRepository(UserRepository)
    private readonly userRepository: UserRepository,
    private readonly publicFileService: PublicFileService,
    private readonly addressService: AddressService,
    private readonly privateFileService: PrivateFileService,
  ) {}

  //...
  public async addPrivateFile(
    userId: string,
    dataBuffer: Buffer,
    filename: string,
  ) {
    return await this.privateFileService.uploadPrivateFile(
      userId,
      dataBuffer,
      filename,
    );
  }

  public async addMultiplePrivateFile(
    userId: string,
    uploadFiles: UploadFileDto[],
  ) {
    return await this.privateFileService.uploadMultiplePrivateFile(
      userId,
      uploadFiles,
    );
  }
  public async deletePrivateFile(userId: string, fileId: string) {
    try {
      const canRemoveFile = await this.userRepository.canRemoveFile(
        userId,
        fileId,
      );
      if (canRemoveFile) {
        await this.privateFileService.deletePrivateFile(fileId);
        return { deleted: true };
      }
      return { deleted: false };
    } catch (error) {
      throw new HttpException(error.message, HttpStatus.INTERNAL_SERVER_ERROR);
    }
  }
}

Update UserController

// user.controller.ts
  @Post('files')
  @UseGuards(JwtAuthGuard)
  @UseInterceptors(FileInterceptor('file'))
  public async addFile(@Req() req: IRequestWithUser, @UploadedFile() file) {
    const { user } = req;
    return await this.userService.addPrivateFile(
      user.id,
      file.buffer,
      file.originalname,
    );
  }

  @Post('files')
  @UseGuards(JwtAuthGuard)
  @UseInterceptors(FilesInterceptor('files', 10))
  public async addMultipleFiles(
    @Req() req: IRequestWithUser,
    @UploadedFiles() files,
  ) {
    const { user } = req;
    const uploadFiles = [] as UploadFileDto[];
    files.forEach((file) => {
      uploadFiles.push({
        dataBuffer: file.buffer,
        filename: file.originalname,
      });
    });
    return await this.userService.addMultiplePrivateFile(user.id, uploadFiles);
  }

  @Delete('files/:fileId')
  @UseGuards(JwtAuthGuard)
  public async deleteFile(
    @Req() req: IRequestWithUser,
    @Param('fileId') fileId: string,
  ) {
    return await this.userService.deletePrivateFile(req.user.id, fileId);
  }

Test with Postman After doing all of the above, our users can start uploading private files.

You can also implement deleting the files in a very similar way as in the previous part.
Accessing private files Since the files we upload above are private, we can’t access them by simply entering a URL. Trying to do so will result in getting an error.

There is more than one way to approach this issue. Let’s start with the most straightforward one.

Fetch files and Generating presigned URLs from AWS S3 as a stream

The first solution to the above issue is to send the file through our API. The most fitting way to do that is to pipe a readable stream that we can get from the AWS SDK to our response. We will work directly with streams and don't need to download the file into the memory server.

The first thing to do is to get a readable stream of data from our Amazon S3 bucket.

Update S3PrivateFileService: src/modules/files/services/s3-private-file.service.ts

//...
 public async createStreamFromFile(fileKey: string) {
  return await this.s3
    .getObject({
      Bucket: this.bucketName,
      Key: fileKey,
    })
    .createReadStream();
}

public async generatePresignedUrl(fileKey: string) {
  const url = await this.s3.getSignedUrlPromise('getObject', {
    Bucket: this.bucketName,
    Key: fileKey,
  });
  return url;
}

Update PrivateFileService: src/modules/files/services/private-file.service.ts

// private-file.service.ts
// ...
public async getPrivateFileFromAWS(fileId: string) {
  const file = await this.getFileById(fileId);
  try {
    const stream = await this.s3PrivateFileService.createStreamFromFile(
      file.key,
    );
    return {
      stream,
      info: file,
    };
  } catch (error) {
    throw new HttpException(error.message, HttpStatus.INTERNAL_SERVER_ERROR);
  }
}

public async generatePresignedUrl(fileKey: string) {
  try {
    return await this.s3PrivateFileService.generatePresignedUrl(fileKey);
  } catch (error) {
    throw new HttpException(error.message, HttpStatus.INTERNAL_SERVER_ERROR);
  }
}

Now we need to make sure if the users should be able to download the file.

Update UserService: src/modules/user/user.service.ts

// user.service.ts
 public async getPrivateFileFromAWS(userId: string, fileId: string) {
  try {
    const file = await this.privateFileService.getPrivateFileFromAWS(fileId);
    if (file.info.owner.id === userId) {
      return file;
    }
    throw new UnauthorizedException();
  } catch (error) {
    if (error.status) {
      throw error;
    }
    throw new HttpException(error.message, HttpStatus.UNAUTHORIZED);
  }
}

public async getAllPrivatesFileFromAWS(userId: string) {
  try {
    const userWithFiles = await this.userRepository.getUserWithFilesById(
      userId,
    );
    if (!userWithFiles) {
      throw new NotFoundException('User not found');
    }
    return Promise.all(
      userWithFiles.files.map(async (file) => {
        const url = await this.privateFileService.generatePresignedUrl(
          file.key,
        );
        return {
          ...file,
          url,
        };
      }),
    );
  } catch (error) {
    if (error.status) {
      throw error;
    }
    throw new HttpException(error.message, HttpStatus.INTERNAL_SERVER_ERROR);
  }
}

Update UserController

// user.service.ts
// ...
@Get('files/:fileId')
@UseGuards(JwtAuthGuard)
public async getUserPrivateFileFromAWS(
  @Req() req: IRequestWithUser,
  @Param('fileId') fileId: string,
) {
  const file = await this.userService.getPrivateFileFromAWS(
    req.user.id,
    fileId,
  );
  file.stream.pipe(req.res);
}

@Get('files')
@UseGuards(JwtAuthGuard)
public async getAllUserFilesFromAWS(@Req() req: IRequestWithUser) {
  return await this.userService.getAllPrivatesFileFromAWS(req.user.id);
}

Now, the user can access all of the files in a very straightforward way.

10. Elasticsearch

Click to expand section

Check the code at branch 10-elasticsearch

Elasticsearch is a distributed, RESTful search and analytics engine capable of addressing a growing number of use cases.

Elastic search is just a really, really fast RESTful search and analytics engine which can interface with various programming languages.

Let's start:

Check awesome article about this part at wanago-nestjs-elasticsearch

Missing docs for this part. Working in progress....

11. Refresh token

Click to expand section

Check the code at branch 11-refresh-token

Check awesome article about this part at wanago-nestjs-refresh-token

Why do we need refresh tokens?

So far, we’ve implemented JWT access tokens. They have a specific expiration time that should be short. If someone steals it from our user, the token is usable just until it expires.

After the user logs in successfully, we send back the access token. Let’s say that it has an expiry of 15 minutes. During this period, it can be used by the user to authenticate while making various requests to our API.

After the expiry time passes, the user needs to log in by again providing the username and password. This does not create the best user experience, unfortunately. On the other hand, increasing the expiry time of our access token might make our API less secure.

The solution to the above issue might be refresh tokens. The basic idea is that on a successful log-in, we create two separate JWT tokens. One is an access token that is valid for 15 minutes. The other one is a refresh token that has an expiry of a week, for example.
How refresh tokens work The user saves both of the tokens in cookies but uses just the access token to authenticate while making requests. It works for 15 minutes without issues. Once the API states that the access token expires, the user needs to perform a refresh.

The crucial thing about storing tokens in cookies is that they should use the httpOnly flag. For more information, check out Cookies: explaining document.cookie and the Set-Cookie header

To refresh the token, the user needs to call a separate endpoint, called /refresh. This time, the refresh token is taken from the cookies and sent to the API. If it is valid and not expired, the user receives the new access token. Thanks to that, there is no need to provide the username and password again.
Addressing some of the potential issues

Unfortunately, we need to consider the situation in which the refresh token is stolen. It is quite a sensitive piece of data, almost as much as the password.

We need to deal with the above issue in some way. The most straightforward way of doing so is changing the JWT secret once we know about the data leak. Doing that would render all of our refresh tokens invalid, and therefore, unusable.

We might not want to log out every user from our application, though. Assuming we know the affected user, we would like to make just one refresh token invalid. JWT is in its core stateless, though.

One of the solutions that we might stumble upon while browsing the web is a blacklist. Every time someone uses a refresh token, we check if it is in the blacklist first. Unfortunately, this does not seem like a solution that would have good enough performance. Checking the blacklist upon every token refresh and keeping it up-to-date might be a demanding task.

An alternative is saving the current refresh token in the database upon logging in. When someone performs a refresh, we check if the token kept in the database matches the provided one. If it is not the case, we reject the request. Thanks to doing the above, we can easily make the token of a particular person invalid by removing it from the database.
Logging out

So far, when the user logged out, we’ve just removed the JWT token from cookies. While this might be a viable solution for tokens with a short expiry time, it creates some issues with refresh tokens. Even though we removed the refresh token from the browser, it is still valid for a long time.

We can address the above issue by removing the refresh token from the database once the user logs out. If someone tries to use the refresh token before it expires, it is not possible anymore.
Preventing logging in on multiple devices

Let’s assume that we provide services that require a monthly payment. Allowing many people to use the same account at the same time might have a negative impact on our business.

Saving the refresh token upon logging in can help us deal with the above issue too. If someone uses the same user credentials successfully, it overwrites the refresh token stored in the database. Thanks to doing that, the previous person is not able to use the old refresh token anymore.
A potential database leak

We’ve mentioned that the refresh token is sensitive data. If it leaks out, the attacker can easily impersonate our user.

We have a similar case with the passwords. This is why we keep hashes of the passwords instead of just plain text. We can improve our refresh token solution similarly.

If we hash our refresh tokens before saving them in the database, we prevent the attacker from using them even if our database is leaked.

Now we start to implement JWT refresh token in Nestjs

Implementation in Nestjs

Add new variables environment:

# .env
JWT_REFRESH_TOKEN_SECRET=somesecretforjwtrefreshtoken
# 30d
JWT_REFRESH_TOKEN_EXPIRATION_TIME= 2592000

And update in node.d.ts

declare namespace NodeJS {
  interface ProcessEnv {
    // ...
    readonly JWT_REFRESH_TOKEN_SECRET: string;
    readonly JWT_REFRESH_TOKEN_EXPIRATION_TIME: string;
  }
}

Create new column for UserEntity to stock a refresh token code encrypted

+ @Column({
+    nullable: true,
+  })
+  @Exclude()
+  public currentHashedRefreshToken?: string;

We also need to create a function for creating a method for creating a cookie with the refresh token and method to save the hash of the current refresh token. We will update in auth.service.ts

// auth.service.ts
// Method to get access token cookie
 public getCookieWithToken(payload: IPayloadJwt) {
  const token = this.jwtService.sign(payload, {
    secret: process.env.JWT_SECRET,
    expiresIn: `${process.env.JWT_EXPIRATION_TIME}s`,
  });
  return `Authorization=${token};HttpOnly;Path=/;Max-Age=${process.env.JWT_EXPIRATION_TIME}`;
}

// Method to get refresh token cookie
public getCookieWithJwtRefreshToken(payload: IPayloadJwt) {
  const token = this.jwtService.sign(payload, {
    secret: process.env.JWT_REFRESH_TOKEN_SECRET,
    expiresIn: `${process.env.JWT_REFRESH_TOKEN_EXPIRATION_TIME}s`,
  });
  const cookie = `Refresh=${token}; HttpOnly; Path=/; Max-Age=${process.env.JWT_REFRESH_TOKEN_EXPIRATION_TIME}`;
  return {
    cookie,
    token,
  };
}

We need create some methods helpers for AuthService to create in auth.repository.ts:

// auth.repository.ts
  public async updateRefreshToken(
  user: User,
  currentHashedRefreshToken: string,
) {
  await this.save({
    ...user,
    currentHashedRefreshToken: currentHashedRefreshToken,
  });
  return user;
}

Let’s make sure that we send both cookies when logging in. Update auth.controller:

@Post('login')
@UseGuards(LocalAuthGuard)
public async login(@Req() req: IRequestWithUser) {
  const { user } = req;
  const payload: IPayloadJwt = {
    userId: user.id,
    email: user.email,
  };
  const accessTokenCookie = this.authService.getCookieWithToken(payload);
  const {
    cookie: refreshTokenCookie,
    token: refreshToken,
  } = this.authService.getCookieWithJwtRefreshToken(payload);
  await this.authService.setCurrentRefreshToken(user, refreshToken);
  this.authService.setHeaderArray(req.res, [
    accessTokenCookie,
    refreshTokenCookie,
  ]);
  return user;
}

Creating an endpoint that uses the refresh token

Now we can start handling the incoming refresh token. For starters, let’s deal with checking if the token from cookies matches the one in the database.

Create method retrieve user from refresh token in auth.service.ts

// auth.service.ts
 public async setCurrentRefreshToken(
  user: User,
  refreshToken: string,
): Promise<User> {
  const salt = await bcrypt.genSalt(10);
  const currentHashedRefreshToken = await bcrypt.hash(refreshToken, salt);

  return await this.authRepository.updateRefreshToken(
    user,
    currentHashedRefreshToken,
  );
}

And method helper from auth.repository.ts

// auth.repository.ts
  // Get user with from refresh token
public async getUserIfRefreshTokenMatches(
  refreshToken: string,
  userId: string,
) {
  const user = await this.getUserById(userId);

  const isRefreshTokenMatching = await bcrypt.compare(
    refreshToken,
    user.currentHashedRefreshToken,
  );
  if (isRefreshTokenMatching) return user;
  return null;
}
public setHeaderSingle(res: Response, cookie: string): void {
  res.setHeader('Set-Cookie', cookie);
}
public setHeaderArray(res: Response, cookies: string[]): void {
  res.setHeader('Set-Cookie', cookies);
}

Create new strategy jwt-refresh-token from PassportStrategy Create new file src/modules/auth/strategies/jwt-refresh-token.strategy.ts

// jwt-refresh-token.strategy.ts
import { IPayloadJwt } from '../auth.interface';
import { Injectable } from '@nestjs/common';
import { ExtractJwt, Strategy } from 'passport-jwt';
import { PassportStrategy } from '@nestjs/passport';
import { Request } from 'express';
import { InjectRepository } from '@nestjs/typeorm';
import { AuthRepository } from '../auth.repository';

@Injectable()
export class JwtRefreshTokenStrategy extends PassportStrategy(
  Strategy,
  'jwt-refresh-token',
) {
  constructor(
    @InjectRepository(AuthRepository)
    private readonly authRepository: AuthRepository,
  ) {
    super({
      jwtFromRequest: ExtractJwt.fromExtractors([
        (req: Request) => {
          return req?.cookies?.Refresh;
        },
      ]),
      ignoreExpiration: false,
      secretOrKey: process.env.JWT_REFRESH_TOKEN_SECRET,
      passReqToCallback: true,
    });
  }
  public async validate(req: Request, payload: IPayloadJwt) {
    const refreshToken = req.cookies?.Refresh;
    return this.authRepository.getUserIfRefreshTokenMatches(
      refreshToken,
      payload.userId,
    );
  }
}

Note: We use the name jwt-refresh-token for the name of guard. And Please note that we use the passReqToCallback parameter so that we can access the cookies in our validate method.

Create new guard : src/modules/auth/guards/jwt-refresh-token.guard.ts

// jwt-refresh-token.guard.ts
import { Injectable } from '@nestjs/common';
import { AuthGuard } from '@nestjs/passport';

@Injectable()
export class JwtRefreshTokenAuthGuard extends AuthGuard('jwt-refresh-token') {}

Update JwtRefreshTokenStrategy in AuthModule

// auth.module.ts
// ...
@Module({
  imports: [
    ConfigModule.forRoot(),
    TypeOrmModule.forFeature([AuthRepository]),
    PassportModule,
    JwtModule.register({}),
  ],
  providers: [AuthService, LocalStrategy, JwtStrategy, JwtRefreshTokenStrategy],
  exports: [AuthService],
  controllers: [AuthController],
})
export class AuthModule {}

Now, the last thing to do is to create the /refresh endpoint in AuthController

// auth.controller.ts
// ...
@UseGuards(JwtRefreshTokenAuthGuard)
@Get('refresh')
public refresh(@Req() req: IRequestWithUser) {
  const { user } = req;
  const payload: IPayloadJwt = {
    userId: user.id,
    email: user.email,
  };
  const accessTokenCookie = this.authService.getCookieWithToken(payload);
  this.authService.setHeaderSingle(req.res, accessTokenCookie);
  return req.user;
}

Note: Please make sure we use @UseGuards(JwtRefreshTokenAuthGuard)

We will make request this endpoint in front-end side.

Improving the log-out flow

Update methods in src/modules/auth/auth.service.ts

// auth.service.ts
public async removeRefreshToken(user: User): Promise<User> {
  return await this.authRepository.clearRefreshToken(user);
}

public clearCookie(res: Response): void {
  const emptyCookie = [
    'Authentication=; HttpOnly; Path=/; Max-Age=0',
    'Refresh=; HttpOnly; Path=/; Max-Age=0',
  ];
  res.setHeader('Set-Cookie', emptyCookie);
}

Use theses methods in our AuthController

// auth.controller.ts
@Post('logout')
@UseGuards(JwtAuthGuard)
public async logout(@Req() req: IRequestWithUser) {
  const { user } = req;
  await this.authService.removeRefreshToken(user);
  this.authService.clearCookie(req.res);
  return {
    logout: true,
  };
}

12. Improve performance of databases

Click to expand section

Check the code at branch 12-database-indexes

Check awesome article of Wanago at:

Improving performance of our Postgres database with indexes
Transaction in Postgres and Typeorm
Using array data type in Postgres
Pagination for entity

Missing docs for this part. Working in progress....

13. Nestjs microservices

Click to expand section

Check the code at branch 13-microservice Check the code at branch 13-microservice-grpc

Project microservice found at nest-email-subscription

Check awesome articles of Marcin Wanago at:

Exploring the idea of microservice
Using RabbitMQ to communicate with microservices
Using gRPC framework to comunicate microservices

Missing docs for this part. Working in progress....

14. Command Query Responsibility Segregation (CQRS Pattern)

Click to expand section

Check the code at branch 14-cqrs

Check awesome article of Wanago at Nestjs CQRS

So far, in our application, we’ve been following a pattern of controllers using services to access and modify the data. While it is a very valid approach, there are other possibilities to look into.

NestJS suggests command-query responsibility segregation (CQRS). In this article, we look into this concept and implement it into our application.

Instead of keeping our logic in services, with CQRS, we use commands to update data and queries to read it. Therefore, we have a separation between performing actions and extracting data. While this might not be beneficial for simple CRUD applications, CQRS might make it easier to incorporate a complex business logic.

Doing the above forces us to avoid mixing domain logic and infrastructural operations. Therefore, it works well with Domain-Driven Design.

Domain-Driven Design is a very broad topic and it will be covered separately

Implementing CQRS in NestJs

The very first thing to do is to install a new package. It includes all of the utilities we need in this article.

$ yarn add @nestjs/cqrs

Let’s explore CQRS by creating a new module in our application that we’ve been working on in this series. This time, we add a comments module.

comment.entity.ts

import { Post } from '@modules/post/post.entity';
import { User } from '@modules/user/user.entity';
import { Column, Entity, ManyToOne, PrimaryGeneratedColumn } from 'typeorm';

@Entity()
export class Comment {
  @PrimaryGeneratedColumn('uuid')
  public id: string;

  @Column()
  public content: string;

  @ManyToOne(() => Post, (post: Post) => post.comments)
  public post: Post;

  @ManyToOne(() => User, (author: User) => author.posts)
  public author: User;
}

...

Missing docs for this part. Working in progress....

15.1 Implementing in-memory cache

Click to expand section

Check the code at branch 15-in-memory-cache

Check awesome article of Wanago about this part:

Implementing in-memory cache

Missing docs for this part. Working in progress....

15.2 Caching with Redis

Click to expand section

Check the code at branch 15-redis

Check awesome article of Wanago about this part:

Caching with Redis

Missing docs for this part. Working in progress....

16. Scheduling, cron jobs with Nodemailer

Click to expand section

Check the code at branch 16-cronjob

Check awesome article of Wanago at Nestjs scheduling, cron job

Missing docs for this part. Working in progress....

17. Realtime chat with Websocket

Click to expand section

Check the code at branch 17-chat

Check awesome article of Wanago at Nestjs Realtime chat with websocket

Missing docs for this part. Working in progress....

References

Docs NestJs

Files

README.md

Latest commit

History

README.md

File metadata and controls

NESTJS FLOW

1. Init project

Installation

Bootstrap projects

Using variable environment (.env)

Modules

Post modules

2. TypeORM

Post modules

Documentation with Swagger/Open API

3. Auth

User

Auth

Installation

Auth service

Auth controller

Complete authentication part

4. Error handling

Exception filter

Validation

5. Serialization

Exclude option

Expose option

Issues with using @Res() decorator

6. Database relationship

7. Testing

8. End to end testing (e2e)

Introduction

Test root folder

Develop

Other modules

9.1 Web service AWS S3

Create IAM user

Create AWS S3 bucket

Update variables enviroments

Create FileModule

9.2 Private bucket AWS

Setting up AWS S3

Update FileModule for Private bucket

Fetch files and Generating presigned URLs from AWS S3 as a stream

10. Elasticsearch

11. Refresh token

Implementation in Nestjs

Creating an endpoint that uses the refresh token

Improving the log-out flow

12. Improve performance of databases

13. Nestjs microservices

14. Command Query Responsibility Segregation (CQRS Pattern)

Implementing CQRS in NestJs

15.1 Implementing in-memory cache

15.2 Caching with Redis

16. Scheduling, cron jobs with Nodemailer

17. Realtime chat with Websocket

References