개요

npm: nestloggednpm

NestLogged

NestLogged 는 NestJS 전용 로깅 데코레이터로, NestJS에서의 실제 로직과 로그를 분리시켜 개발자가 실제 로직만을 신경쓸 수 있도록 간단하고 유연한 방법을 제공합니다.

클래스, 함수, 파라미터에 붙이는 몇 가지 간단한 데코레이터로 바로 로그를 얻을 수 있습니다.

NestLogged 데코레이터는 로거를 초기화하고 로거에 범위를 추가한 뒤 호출과 반환 시에 로그를 출력하며, 파라미터의 값을 로그에 포함하거나 반환 값을 포함하는 등의 기능을 포함하고 있습니다.

설치

$ npm install nestlogged

또는

$ yarn add nestlogged

사용 예제

일반적인 예제의 경우:

cats.controller.ts

@Controller('cats')
export class CatsController {
  private readonly logger = new Logger(CatsController.name);
  
  constructor(private catsService: CatsService) {}
  
  @Get(':name')
  findCatByName(
    @Param('name')
    name: string
  ) {
    this.logger.log(`/cats/:name called with name=${name}`);
    const cat = this.catsService.findCatByName(name);
    if (!cat) {
      this.logger.error(`There is no cat named ${name}..`);
      throw new NotFoundException('cat_not_found');
    }
    this.logger.log(`Found cat ${cat}!!`)
    return cat;
  }
}

cats.service.ts

@Injectable()
export class CatsService {
  private readonly logger = new Logger(CatsService.name);
  private readonly cats = [
    {
      name: "Adela"
    },
    {
      name: "Baba"
    }
  ];
  
  findCatByName(name: string): string {
    this.logger.log(`findCatByName called with name=${name}`)
    const foundCat = this.cats.filter((cat) => cat.name === name);
    this.logger.log(`found ${foundCat.length} cats`)
    if (!foundCat.length) return null;
    this.logger.log(`returning cat ${foundCat[0].name}`)
    return foundCat[0].name
  }
}

Console (success with name=Baba)

[Nest] 22072  - 01/10/2024, 2:26:02 AM     LOG [CatsController] /cats/:name called with name=Baba
[Nest] 22072  - 01/10/2024, 2:26:02 AM     LOG [CatsService] findCatByName called with name=Baba
[Nest] 22072  - 01/10/2024, 2:26:02 AM     LOG [CatsService] found 1 cats
[Nest] 22072  - 01/10/2024, 2:26:02 AM     LOG [CatsService] returning cat Baba
[Nest] 22072  - 01/10/2024, 2:26:02 AM     LOG [CatsController] Found cat Baba!!

Console (fail with name=baba)

[Nest] 13064  - 01/10/2024, 2:27:29 AM     LOG [CatsController] /cats/:name called with name=baba
[Nest] 13064  - 01/10/2024, 2:27:29 AM     LOG [CatsService] findCatByName called with name=baba
[Nest] 13064  - 01/10/2024, 2:27:29 AM     LOG [CatsService] found 0 cats
[Nest] 13064  - 01/10/2024, 2:27:29 AM   ERROR [CatsController] There is no cat named baba..

NestLogged 데코레이터 적용 시:

cats.controller.ts

@LoggedController('cats')
export class CatsController {
  constructor(private catsService: CatsService) {}
  
  @Get(':name')
  findCatByName(
    @LoggedParam('name')('name') name: string,
    @InjectLogger logger: ScopedLogger,
  ) {
    const cat = this.catsService.findCatByName(name, logger);
    if (!cat) {
      throw new NotFoundException('cat_not_found');
    }
    logger.log(`Found cat ${cat}!!`)
    return cat;
  }
}

cats.service.ts

@LoggedInjectable()
export class CatsService {
  private readonly cats = [
    {
      name: "Adela"
    },
    {
      name: "Baba"
    }
  ];
  
  @Returns('name')
  findCatByName(
    @Logged('name') name: string,
    @InjectLogger logger: ScopedLogger,
  ): string {
    const foundCat = this.cats.filter((cat) => cat.name === name);
    this.logger.log(`found ${foundCat.length} cats`)
    if (!foundCat.length) return null;
    return foundCat[0].name
  }
}

Console (success with name=Baba)

[Nest] 13784  - 01/10/2024, 2:14:54 AM     LOG [CatsController] findCatByName(w4ZOccMCT6qaQRFJig82nw/0000000000): HIT HTTP CatsController:::name[GET] (findCatByName) WITH name=Baba
[Nest] 13784  - 01/10/2024, 2:14:54 AM     LOG [CatsController] findCatByName(w4ZOccMCT6qaQRFJig82nw/0000000000): -> findCatByName: CALL findCatByName WITH name=Baba
[Nest] 13784  - 01/10/2024, 2:14:54 AM     LOG [CatsController] findCatByName(w4ZOccMCT6qaQRFJig82nw/0000000000): -> findCatByName: found 1 cats
[Nest] 13784  - 01/10/2024, 2:14:54 AM     LOG [CatsController] findCatByName(w4ZOccMCT6qaQRFJig82nw/0000000000): -> findCatByName: RETURNED findCatByName Baba
[Nest] 13784  - 01/10/2024, 2:14:54 AM     LOG [CatsController] findCatByName(w4ZOccMCT6qaQRFJig82nw/0000000000): Found cat Baba!!
[Nest] 13784  - 01/10/2024, 2:14:54 AM     LOG [CatsController] findCatByName(w4ZOccMCT6qaQRFJig82nw/0000000000): RETURNED HTTP CatsController:::name[GET] (findCatByName)

Console (fail with nam=baba)

[Nest] 20668  - 01/10/2024, 2:28:42 AM     LOG [CatsController] findCatByName(sIb8e7UUTyubQecsS+rHyw/0000000001): HIT HTTP CatsController:::name[GET] (findCatByName) WITH name=baba
[Nest] 20668  - 01/10/2024, 2:28:42 AM     LOG [CatsController] findCatByName(sIb8e7UUTyubQecsS+rHyw/0000000001): -> findCatByName: CALL findCatByName WITH name=baba
[Nest] 20668  - 01/10/2024, 2:28:42 AM     LOG [CatsController] findCatByName(sIb8e7UUTyubQecsS+rHyw/0000000001): -> findCatByName: found 0 cats
[Nest] 20668  - 01/10/2024, 2:28:42 AM     LOG [CatsController] findCatByName(sIb8e7UUTyubQecsS+rHyw/0000000001): -> findCatByName: RETURNED findCatByName null
[Nest] 20668  - 01/10/2024, 2:28:42 AM   ERROR [CatsController] findCatByName(sIb8e7UUTyubQecsS+rHyw/0000000001): WHILE HTTP CatsController:::name[GET] (findCatByName) ERROR NotFoundException: cat_not_found