NestJS Full Course 2024

Introduction

This tutorial provides a comprehensive step-by-step guide to mastering NestJS, a powerful framework for building server-side applications. NestJS offers a more structured and scalable approach compared to traditional frameworks like Express.js. This course is perfect for beginners and developers familiar with Express.js who want to enhance their skills in building robust applications.

Step 1: Understanding NestJS

• What is NestJS: NestJS is a progressive Node.js framework for building efficient and scalable server-side applications. It uses TypeScript and is heavily inspired by Angular's architecture.
• Why Choose NestJS Over Express.js:
  • Modular architecture for better organization
  • Built-in support for dependency injection
  • Enhanced testing capabilities
  • Support for GraphQL and WebSockets out of the box

Step 2: Core Concepts of NestJS

• Modules: The fundamental building blocks in NestJS. Every NestJS application consists of at least one module.
  • Create modules using @Module() decorator.
• Controllers: Handle incoming requests and return responses. They define routes for the application.
  • Use the @Controller() decorator to define controllers.
• Services: Contain business logic. Services are typically used to interact with databases or external APIs.
  • Create services using the @Injectable() decorator.
• Dependency Injection: A design pattern that allows a class to receive its dependencies from external sources rather than creating them itself.

Step 3: Application Structure

• File Structure: Organize your files for maintainability.
  • Follow a modular structure with separate directories for modules, controllers, and services.
• Example Structure:

  src/
    ├── app.module.ts
    ├── main.ts
    ├── users/
    │   ├── users.module.ts
    │   ├── users.controller.ts
    │   └── users.service.ts
  

Step 4: Building a Simple API with CRUD Operations

• Setting Up the Project:
  • Install NestJS CLI globally using:

    npm install -g @nestjs/cli
    

  • Create a new project:

    nest new project-name
    

• Implementing CRUD:
  • Define routes in the controller for Create, Read, Update, and Delete operations.
  • Use services to handle the logic behind these operations.

Step 5: Integrating with Databases

• Choose a Database: You can use SQL (PostgreSQL, MySQL) or NoSQL (MongoDB).
• ORM/ODM: Use TypeORM or Mongoose for database interactions.
• Example with TypeORM:
  • Install TypeORM and the required database driver:

    npm install --save @nestjs/typeorm typeorm mysql2
    

  • Set up TypeORM in your module:

    import { TypeOrmModule } from '@nestjs/typeorm';
    
    @Module({
      imports: [
        TypeOrmModule.forRoot({
          type: 'mysql',
          host: 'localhost',
          port: 3306,
          username: 'test',
          password: 'test',
          database: 'test',
          entities: [__dirname + '/**/*.entity{.ts,.js}'],
          synchronize: true,
        }),
      ],
    })
    

Step 6: User Authentication and Authorization

• Implement Authentication: Use Passport.js for implementing authentication strategies.
• Creating Guards: Use guards for route protection.
  • Example:

    import { Injectable, CanActivate, ExecutionContext } from '@nestjs/common';
    
    @Injectable()
    export class AuthGuard implements CanActivate {
      canActivate(context: ExecutionContext): boolean {
        // Logic to check if the user is authenticated
        return true;
      }
    }
    

Step 7: Data Serialization

• Using DTOs: Define Data Transfer Objects (DTOs) for validating and transforming data.
• Example DTO:

  import { IsString, IsInt } from 'class-validator';
  
  export class CreateUserDto {
    @IsString()
    readonly name: string;
  
    @IsInt()
    readonly age: number;
  }
  

Step 8: Testing and Deployment Strategies

• Testing: Use Jest for testing your application.
  • Write unit and integration tests to ensure code quality.
• Deployment: Choose a cloud provider (e.g., AWS, Heroku) for deploying your NestJS application.

Conclusion

In this tutorial, you learned about NestJS, its core concepts, and how to build a simple API. You also explored how to integrate with databases, implement user authentication, and prepare your application for testing and deployment. As you progress, consider diving deeper into advanced features and best practices within the NestJS ecosystem. Happy coding!