How To Install And Setup First NestJS Application?

NestJS is a progressive Node.js framework that simplifies the creation of server-side applications. Whether you're building REST APIs, microservices, or GraphQL applications, NestJS offers a structured and modern approach to development. This article will guide you through the installation and initial setup of a NestJS project.

Prerequisites

• NodeJS and NPM
• Nest CLI

Steps to Install and Setup NestJS application

Step 1: Install the Nest CLI

The Nest CLI provides an efficient way to create and manage NestJS projects. To install the CLI globally, run the following command in your terminal:

npm install -g @nestjs/cli

You can verify the installation by checking the CLI version:

nest --version

Step 2: Create a New Project

To create a new NestJS project, use the Nest CLI:

nest new nest-gfg

The CLI will prompt you to choose a package manager (npm or yarn) for installing dependencies. After making your choice, the CLI sets up the project structure and installs the necessary packages.

Navigate into your project directory:

cd project-name

Folder Structure

Dependencies

 "dependencies": {
      "@nestjs/common": "^10.0.0",
      "@nestjs/core": "^10.0.0",
      "@nestjs/platform-express": "^10.0.0",
      "reflect-metadata": "^0.2.0",
      "rxjs": "^7.8.1"
  }

Key Files and Directories

• src: Contains the source code of your application.
• app.controller.ts: Defines a basic controller.
• app.module.ts: The root module of your application.
• app.service.ts: A basic service.
• main.ts: The entry point of your application.
• test: Contains test files.
• package.json: Lists the dependencies and scripts for your project.
• tsconfig.json: TypeScript configuration file.
• nest-cli.json: Nest CLI configuration file.

Example: Here is a basic NestJS application

//app.controller.ts

import { Controller, Get } from '@nestjs/common';
import { AppService } from './app.service';

@Controller()
export class AppController {
    constructor(private readonly appService: AppService) { }

    @Get()
    getHello(): string {
        return this.appService.getHello();
    }
}

//app.service.ts

import { Injectable } from '@nestjs/common';

@Injectable()
export class AppService {
    getHello(): string {
        return 'Hello, NestJS!';
    }
}

//app.module.ts

import { Module } from '@nestjs/common';
import { AppController } from './app.controller';
import { AppService } from './app.service';

@Module({
    imports: [],
    controllers: [AppController],
    providers: [AppService],
})
export class AppModule { }

//main.ts

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

async function bootstrap() {
    const app = await NestFactory.create(AppModule);
    await app.listen(3000);
}
bootstrap();

Step 3: Run the Application

To start the application, use the following command:

npm run start

By default, the application runs on 'http://localhost:3000'.

You can also run the application in development mode with live reloading:

npm run start:dev

This mode watches for file changes and automatically restarts the server.

Output

Additional Tips and Best Practices

1. Use TypeScript Features: Use TypeScript’s static typing and interfaces for more robust code.

2. Organize Your Code: Keep your code modular by creating separate modules for different features or domains.

3. Use DTOs: Use Data Transfer Objects (DTOs) to validate and transform incoming request data.

4. Enable CORS: Enable Cross-Origin Resource Sharing (CORS) if your application needs to interact with clients from different origins.

5. Security: Use guards and interceptors to handle authentication and authorization.