NestJS でのバリデーション設定

• ライブラリの登録

npm i class-validator, class-transformer -S

• ValidationPipe有効化

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  app.useGlobalPipes(new ValidationPipe());

@UsePipes(new ValidationPipe()) を使ってメソッドごとの設定も可

• DTO の作成

export class UserDto implements User {
  @IsString()
  readonly id: string;

  @IsString()
  readonly name: string;

  @IsNumber()
  readonly age: number;

  @IsString()
  @IsOptional()
  readonly organization: string;
}

• 実行例

% curl -XPOST localhost:3000/api/v1/user -H "Content-Type: application/json" -d '{"id": "aa", "name": "aa", "age": "aaa"}'
{"statusCode":400,"message":["age must be a number conforming to the specified constraints"],"error":"Bad Request"}