Nestjs Global Validation Pipe unable to Parse Boolean Query Param-CodePudding

In following controller, in the GET call I intend to pass a boolean parameter.

@Controller('tests')
export class TestController {
    constructor(private readonly testService: TestService) {}

    @Get()
    async getTests(@Query() params: QueryParamDto) {
        return await this.testService.getTests(params.var);
    }
}

and the Service method understands the type of params.var as a boolean.

@Injectable()
export class TestService {
    @Get()
    async getTests(var: boolean) {
        return ...;
    }
}

The QueryParamDto looks like.

export class QueryParamDto {
    @IsDefined()
    @IsBoolean()
    var: boolean;
}

I have defined a Global Validation Pipe in main.ts.

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  app.useGlobalPipes(
    new ValidationPipe({
      transform: true,
    }),
  );
  await app.listen(3000);
}
bootstrap();

However, when I make a call to the endpoint /tests?var=true it is unable to parse the var as a boolean and errors.

{
    "statusCode": 400,
    "message": [
        "var must be a boolean value"
    ],
    "error": "Bad Request"
}

My understanding is that app.useGlobalPipes(new ValidationPipe({transform: true...}) should automatically parse the params type as defined in the Dto, in this case var as boolean in QueryParamDto.

CodePudding user response：

transform means that the result of plainToClass from class-transformer will be the resulting parameter passed to your route handler. Normally this would be fine, but query and url parameters always come in as strings, so you either need to add your own @Transform() to make them get transformed properly, or use the transformOptions.enableImplicitConversion option