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![/src/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 { }](https://image.slidesharecdn.com/nestjs-201217055528/75/NestJS-8-2048.jpg)
![/src/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 { }](https://crownmelresort.com/image.slidesharecdn.com/nestjs-201217055528/75/NestJS-8-2048.jpg)
Uploaded byWilson Su
NestJS
NestJS is a framework for building Node.js server-side applications, fully supporting TypeScript and designed for creating scalable, maintainable applications. The document provides a detailed introduction to creating and managing a NestJS project, including examples of modules, controllers, services, middleware, and routing. It also highlights error handling by demonstrating a bad API call that triggers validation errors.
In this document
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NestJS is a TypeScript-based framework for building scalable Node.js applications, inspired by Angular.
Overview of components like Controllers, Modules, Providers, and Guards in NestJS architecture.
Instructions to create a new NestJS application and basic files structure including AppService, AppController, and AppModule.
Overview of commands available in Nest CLI for building, starting, and generating files in a NestJS application.
Introduction to middleware in NestJS including a LoggerMiddleware example and its configuration in AppModule.
Routing setup in NestJS with an example CatsController demonstrating various HTTP methods.
Implementation of pipes in NestJS, with ParseIntPipe in a cats controller and error handling for bad requests.
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NestJS
- 1.
- 2. Introduction NestJS − is aframework for building Node.js server-side applications − is built with and fully supports TypeScript − allows developers to create testable, scalable, loosely coupled, and easily maintainable applications − the architecture is heavily inspired by Angular
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- 5. Create a NewProject $ npm i -g @nestjs/cli $ nest new my-nest-app my-nest-app ㄴ src ㄴ app.controller.spec.ts ㄴ app.controller.ts ㄴ app.module.ts ㄴ app.service.ts ㄴ main.ts ㄴ test ㄴ app.e2e-spec.ts ㄴ jest-e2e.json ㄴ nest-cli.json ㄴ package.json ㄴ tsconfig.build.json ㄴ tsconfig.json
- 6. /src/app.service.ts import { Injectable} from '@nestjs/common'; @Injectable() export class AppService { getHello(): string { return 'Hello World!'; } }
- 7. /src/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(); } }
- 8. /src/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 { }
- 9. /src/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();
- 10. Nest CLI # Compilesand runs an application in watch mode $ nest start --watch # Compiles an application or workspace into an output folder. $ nest build # Generates files based on a schematic $ nest generate module cats $ nest generate controller cats $ nest generate service cats ...
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- 13. /src/middleware/logger.middleware import { Injectable,NestMiddleware } from '@nestjs/common'; import { Request, Response } from 'express'; @Injectable() export class LoggerMiddleware implements NestMiddleware { use(req: Request, res: Response, next: () => void) { const now = new Date().toISOString(); const { method, originalUrl } = req; console.log(`${now} ${method} ${originalUrl}`); next(); } }
- 14. /src/app.module.ts import { Module,MiddlewareConsumer } from '@nestjs/common'; import { CatsModule } from './cats/cats.module'; import { CatsController } from './cats/cats.controller'; import { LoggerMiddleware } from './middleware/logger.middleware'; @Module({ ... }) export class AppModule { configure(consumer: MiddlewareConsumer) { consumer.apply(LoggerMiddleware) .forRoutes(CatsController); } }
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- 16. /src/cats/cats.controller @Controller('cats') export class CatsController{ @Get() // GET /cats fetchAll(): Cats { ... } @Post() // POST /cats create(): Promise<Cat> { ... } @Delete(':id') // DELETE /cats/1 removeOne() { ... } }
- 17.
- 18. /src/cats/cats.controller import { ParseIntPipe,... } from '@nestjs/common'; import { Response } from 'express'; import { cats } from './cats.mock'; @Controller('cats') export class CatsController { @Get(':id') findOne(@Param('id', ParseIntPipe) id: number, @Res() res: Response) { const target = cats.find(cat => cat.id === id); res.status(HttpStatus.OK).json(target); } }
- 19. A Bad APICall GET /cats/abc /* Nest will throw an exception */ { "statusCode": 400, "message": "Validation failed (numeric string is expected)", "error": "Bad Request" }