NestJS introduction

NestJS introduction made during Node.js Paris meetup (https://www.meetup.com/fr-FR/Nodejs-Paris/events/263164020/)

Transcript

1. October 9, 2019 | Node.js Paris | Sylvain Pontoreau
   NestJS introduction
   NestJS
   

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2. Writer
   In ❤ with
   Co-organizer
   Who I am?
   @spontoreau
   Formerly Microsoft
   

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3. Paris TypeScript
   @ParisTypeScript
   www.typescript.paris
   

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4. What is NestJS?
   • A Node.js MVC framework
   • Progressive
   • Written in TypeScript
   • Project organization inspired by Angular
   • A lot of modules:
   • Endpoint: Rest, GraphQL, WebSocket, ...
   • Data: TypeORM, Mongoose, ...
   • Communication: MQTT, RabbitMQ, gRPC, …
   • Others: Elastic Search, OpenAPI, Health checks, JWT, CQRS ...
   • Amazing documentation: https://docs.nestjs.com
   • Huge community (20k stars on Github, 120 contributors on the core)
   • CLI
   

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5. Create a project
   • Install CLI:
   • Create a project:
   $ npm install –g @nestjs/cli
   $ nest new appName
   

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6. Controllers
   import { Controller, Get } from '@nestjs/common';
   @Controller()
   export class UserController {
   @Get('hello')
   get(): string {
   return 'Hello world!';
   }
   }
   • Verbs:
   • @Get
   • @Post
   • @Put
   • @Delete
   • @Patch
   • ...
   • Actions & decorators:
   • @Param(key?: string) -> req.params
   • @Body(key?: string) -> req.body
   • @Headers(key?: string)-> req.headers
   • @Request(), @Response(), @Next()
   • ...
   

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7. Services / Providers
   • A dependency to inject
   • Close to the Angular concept
   • Have to be injected
   • @Injectable
   • Example:
   import { Injectable } from '@nestjs/common';
   @Injectable()
   export class UserService {
   findAll(): User[] {
   return [
   // ...
   ];
   }
   }
   import { Controller, Get } from '@nestjs/common';
   import { UserService } from 'user.service';
   @Controller()
   export class UserController {
   constructor(
   private readonly userService: UserService
   ) { }
   @Get()
   getAll(): User[] {
   this.userService.findAll();
   }
   }
   user.service.ts user.controller.ts
   

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8. Modules
   • Organize the application structure
   • A class annotated with @Module()
   • Contains:
   • providers, controllers, imports, exports
   • Example:
   import { Module } from '@nestjs/common';
   import { UserService } from './user.service';
   import { UserController } from './user.controller';
   @Module({
   imports: [],
   controllers: [UserController],
   providers: [
   UserService,
   ],
   })
   export class UserModule {}
   

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9. Other capabilities
   • Middleware
   import {
   Injectable,
   NestMiddleware
   } from '@nestjs/common';
   import {
   Request,
   Response
   } from 'express';
   @Injectable()
   export class LoggerMiddleware implements NestMiddleware {
   use(req: Request, res: Response, next: Function) {
   console.log('Request...');
   next();
   }
   }
   import {
   Module,
   NestModule,
   MiddlewareConsumer
   } from '@nestjs/common';
   import {
   LoggerMiddleware
   } from './common/middleware/logger.middleware';
   import { UserModule } from './user/user.module';
   import { UserController } from './user.controller';
   @Module({ imports: [UserModule], })
   export class AppModule implements NestModule {
   configure(consumer: MiddlewareConsumer) {
   consumer.apply(LoggerMiddleware)
   .forRoutes(UserController);
   }
   }
   logger.middleware.ts app.module.ts
   

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10. Other capabilities
    • Validation with class-validator
    import {
    IsString,
    IsEmail,
    IsNotEmpty
    } from 'class-validator';
    export class PostUserModel {
    @IsNotEmpty()
    @IsString()
    firstName: string;
    @IsNotEmpty()
    @IsString()
    lastName: string;
    @IsNotEmpty()
    @IsEmail()
    email: string;
    }
    import { NestFactory } from '@nestjs/core';
    import { AppModule } from './app.module';
    import { ValidationPipe } from '@nestjs/common';
    async function bootstrap() {
    const app = await NestFactory.create(AppModule);
    app.useGlobalPipes(new ValidationPipe())
    await app.listen(3000);
    }
    bootstrap();
    postUser.model.ts main.ts
    

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11. Data access
    • Example with TypeORM:
    import {
    Entity,
    Column,
    PrimaryGeneratedColumn
    } from 'typeorm';
    @Entity()
    export class User {
    @PrimaryGeneratedColumn()
    id: number;
    @Column()
    firstName: string;
    @Column()
    lastName: string;
    @Column()
    email: string;
    }
    import { createConnection } from 'typeorm';
    export const databaseProviders = [
    {
    provide: 'DatabaseConnection',
    useFactory: async () => await createConnection({
    type: 'mysql',
    // ...
    })
    },
    ];
    user.entity.ts
    database.provider.ts
    

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12. Data access
    • Example with TypeORM:
    import { Injectable, Inject } from '@nestjs/common';
    import { Repository, Connection } from 'typeorm';
    import { User } from './user.entity';
    @Injectable()
    export class UserService {
    private readonly userRepository: Repository
    constructor(
    @Inject('DatabaseConnection')
    connection: Connection
    ) {
    this.userRepository = connection.getRepository(User);
    }
    async findAll(): Promise {
    return await this.userRepository.find();
    }
    }
    user.service.ts
    

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13. Open API
    • Installation:
    import { NestFactory } from '@nestjs/core';
    import { SwaggerModule, DocumentBuilder } from '@nestjs/swagger';
    import { ApplicationModule } from './app.module';
    async function bootstrap() {
    const app = await NestFactory.create(ApplicationModule);
    const options = new DocumentBuilder()
    .setTitle('User API')
    .setDescription('The user API description')
    .setVersion('1.0')
    .addTag('user')
    .build();
    const document = SwaggerModule.createDocument(app, options);
    SwaggerModule.setup('api', app, document);
    await app.listen(3000);
    }
    bootstrap();
    $ npm install --save @nestjs/swagger swagger-ui-express
    • Decorators:
    • @ApiModelProperty
    • @ApiModelPropertyOptional
    • @ApiImplicitQuery
    • @ApiUseTags
    • @ApiResponse
    • @ApiBearerAuth
    • ...
    

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14. Demo
    

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15. Resources
    • NestJS website:
    https://nestjs.com
    • NestJS & Fastify:
    https://docs.nestjs.com/techniques/performance
    • Demo (Github repository):
    https://github.com/spontoreau/nestjs-nodejs-paris
    

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16. Questions?
    

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17. Thank you!
    

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