Learn NestJS – Complete Course

Introduction

This tutorial is designed to guide you through the essentials of NestJS, a powerful framework for building efficient, scalable web applications using Node.js. Whether you're a beginner or looking to solidify your understanding, this comprehensive course covers everything from project setup to advanced features like GraphQL and file uploads.

Step 1: Understanding NestJS

• NestJS is a progressive Node.js framework designed for building efficient server-side applications.
• It uses TypeScript by default, enhancing the development experience with type safety.
• Key features include a modular architecture, dependency injection, and built-in support for web sockets and GraphQL.

Step 2: Creating a NestJS Project

• Install Nest CLI if you haven't already:

  npm i -g @nestjs/cli
  

• Create a new project:

  nest new project-name
  

• Navigate into your project directory:

  cd project-name
  

Step 3: Exploring the NestJS Directory Structure

• Familiarize yourself with the main directories:
  • src: Contains application code.
  • modules: Group related components.
  • controllers: Define endpoints.
  • services: Business logic and data handling.

Step 4: Creating a Controller

• Generate a new controller:

  nest generate controller controller-name
  

• Implement your controller logic within the newly created file.

Step 5: Creating a Service

• Generate a service:

  nest generate service service-name
  

• Use the service in your controller to handle business logic.

Step 6: Creating a Module

• Generate a module to group your controller and service:

  nest generate module module-name
  

Step 7: Implementing Middleware

• Create middleware to intercept requests:

  import { Injectable, NestMiddleware } from '@nestjs/common';
  
  @Injectable()
  export class LoggerMiddleware implements NestMiddleware {
    use(req: Request, res: Response, next: Function) {
      console.log('Request...', req);
      next();
    }
  }
  

Step 8: Handling Errors with Exception Filters

• Create a custom exception filter to manage errors globally.

Step 9: Validating Input with Class Validator

• Use class-validator to enforce validation rules on incoming requests.

Step 10: Establishing Database Connection

• Use TypeORM or Mongoose to connect to your database.
• Install dependencies:

  npm install @nestjs/typeorm typeorm sqlite3
  

• Configure your database module in app.module.ts.

Step 11: Creating Entities

• Define entities representing your database tables.

Step 12: CRUD Operations

• Implement Create, Read, Update, and Delete operations for your entities.

Step 13: User Authentication

• Implement user signup and login functionality.
• Use JWT for token-based authentication.

Step 14: Configuring Environment Variables

• Use dotenv to manage environment-specific settings.
• Install dotenv:

  npm install dotenv
  

Step 15: Setting Up Swagger for API Documentation

• Install Swagger to document your API:

  npm install @nestjs/swagger swagger-ui-express
  

• Add Swagger setup in your main application file.

Step 16: Testing with Jest

• Write unit tests for your controllers and services using Jest.
• Generate tests using the NestJS CLI.

Step 17: Using GraphQL

• Set up a GraphQL server and define your schema.
• Implement queries and mutations.

Step 18: Real-Time Features with Websockets

• Create a websocket gateway to handle real-time communication.

Step 19: File Upload Handling

• Use the Multer package for file uploads.
• Set up routes to handle file uploads in your controllers.

Step 20: Deploying the Application

• Use platforms like Railway or Heroku to deploy your NestJS application.
• Push your source code to a GitHub repository for version control.

Conclusion

This tutorial has provided a structured approach to mastering NestJS, from project setup to deployment. As you continue your learning journey, consider exploring advanced features like caching and transactions. Dive into the provided resources to deepen your understanding and practice your skills. Happy coding!