nestjs-example

Finally JavaScript has something useful for backend development...

let's quickly guide its basics....

create default boilerplate

npx @nestjs/cli new nestjs-example
cd nestjs-example
npm start

structure

starting point

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();

nest app module

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 {}

controller

src/app.controller.ts

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

@Controller() // http://127.0.0.1:3000/**
export class AppController {
  constructor(private readonly appService: AppService) {}

  @Get() // -> GET /
  getHello(): string {
    return this.appService.getHello();
  }
}

service

this service will be injected in controller via constructor (see above)

src/app.service.ts

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

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

testing

as we can see, how we have only one endpoint: GET / which should hello:

http :3000

response

HTTP/1.1 200 OK
Connection: keep-alive
Content-Length: 12
Content-Type: text/html; charset=utf-8
Date: Sun, 09 Feb 2020 13:13:44 GMT
ETag: W/"c-Lve95gjOVATpfV8EL5X4nxwjKHE"
X-Powered-By: Express

Hello World!

implement a feature

if you familiar with ng cli (@angular/cli from Angular framework) it would be very similar!

new module

let's implement Maksimko's module:

npx @nestjs/cli generate module maksimko
#CREATE /src/maksimko/maksimko.module.ts (85 bytes)
#UPDATE /src/app.module.ts (324 bytes)

verify main module has been updated:

src/app.module.ts

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

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

as you can see, now imports array is not empty and contains created MaksimkoModule:

src/maksimko/maksimko.module.ts

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

@Module({})
export class MaksimkoModule {}

new controller

similarly, let's generate new controller

npx @nestjs/cli generate controller maksimko
#CREATE /src/maksimko/maksimko.controller.spec.ts (507 bytes)
#CREATE /src/maksimko/maksimko.controller.ts (105 bytes)
#UPDATE /src/maksimko/maksimko.module.ts (182 bytes)

now maksimko module should be updated:

src/maksimko/maksimko.module.ts

import { Module } from '@nestjs/common';
import { MaksimkoController } from './maksimko.controller';

@Module({
  controllers: [MaksimkoController]
})
export class MaksimkoModule {}

and new controller created:

src/maksimko/maksimko.controller.ts

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

@Controller('maksimko') // http://127.0.0.21:3000/maksimko/**
export class MaksimkoController {}

new service

finally let's similarly create new service:

npx @nestjs/cli generate service maksimko
#CREATE /src/maksimko/maksimko.service.spec.ts (474 bytes)
#CREATE /src/maksimko/maksimko.service.ts (92 bytes)
#UPDATE /src/maksimko/maksimko.module.ts (268 bytes)

src/maksimko/maksimko.module.ts

import { Module } from '@nestjs/common';
import { MaksimkoController } from './maksimko.controller';
import { MaksimkoService } from './maksimko.service';

@Module({
  controllers: [MaksimkoController],
  providers: [MaksimkoService]
})
export class MaksimkoModule {}

src/maksimko/maksimko.service.ts

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

@Injectable()
export class MaksimkoService {}

implementation

service

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

@Injectable()
export class MaksimkoService {
  wtf(what: string): string {
    return `O.o ${what}?`;
  }
}

controller

import { Controller, Param, Post } from '@nestjs/common';
import { MaksimkoService } from './maksimko.service';

@Controller('maksimko')
export class MaksimkoController {

  constructor(private maksimkoService: MaksimkoService) {}

  @Post('/wtf/:what')
  async wtf(@Param('what') what: string): Promise<string> {
    return this.maksimkoService.wtf(what);
  }
}

testing

http post :3000/maksimko/wtf/ololo

output:

HTTP/1.1 201 Created
Connection: keep-alive
Content-Length: 10
Content-Type: text/html; charset=utf-8
Date: Sun, 09 Feb 2020 15:22:17 GMT
ETag: W/"a-PbhLKehORdMno9Pz2s34zAbmS0I"
X-Powered-By: Express

O.o ololo?

License

Nest is MIT licensed.

resoiurces

• Official documentation
• project GitHub repo: nestjs/nest
• YouTube: NestJS For Absolute Beginners