I have defined custom pipe in Nest.js

 @Injectable()
export class QueryValidationPipe implements PipeTransform<GetDto> {
    public transform(value: GetDto, metadata: ArgumentMetadata): GetDto {
      console.log('TEST');
      (...)
      return value;
}

I'm using it in controller for certain GET method in controller A. I'm using Nest.js @Query decorator:

@Get()
@UsePipes(new QueryValidationPipe())
@UseFilters(new ExceptionFilters())
public async getMethod(@Query() query: GetDto) {
    (...)
}

And it works fine, for every request, pipe is logging test message to console. Now in controller B I'm using same decorator, but for method with underlying req and res object as parameters:

@Get()
@UsePipes(new QueryValidationPipe())
@UseFilters(new ExceptionFilters())
public async getMethodTo(@Req() req: GetRequest, @Res() res: Response): Promise<Response> {
    (...)
}

Here it doesn't work. Pipe transform method is not called despite requests being received by above method. What can be cause of this? I didn't found any word in documentation about pipes not working when @Req and @Res parameters are used in method.

And if that's the case (it seems it is), how can I fix this? I can't just use @Query query method parameter because I need to send back different headers depending on query param.

I have defined custom pipe in Nest.js

 @Injectable()
export class QueryValidationPipe implements PipeTransform<GetDto> {
    public transform(value: GetDto, metadata: ArgumentMetadata): GetDto {
      console.log('TEST');
      (...)
      return value;
}

I'm using it in controller for certain GET method in controller A. I'm using Nest.js @Query decorator:

@Get()
@UsePipes(new QueryValidationPipe())
@UseFilters(new ExceptionFilters())
public async getMethod(@Query() query: GetDto) {
    (...)
}

And it works fine, for every request, pipe is logging test message to console. Now in controller B I'm using same decorator, but for method with underlying req and res object as parameters:

@Get()
@UsePipes(new QueryValidationPipe())
@UseFilters(new ExceptionFilters())
public async getMethodTo(@Req() req: GetRequest, @Res() res: Response): Promise<Response> {
    (...)
}

Here it doesn't work. Pipe transform method is not called despite requests being received by above method. What can be cause of this? I didn't found any word in documentation about pipes not working when @Req and @Res parameters are used in method.

And if that's the case (it seems it is), how can I fix this? I can't just use @Query query method parameter because I need to send back different headers depending on query param.

• javascript
• node.js
• nestjs

1 Answer 1

Pipes only work for @Body(), @Param(), @Query() and custom decorators in the REST context. There's a brief mention here, but that should definitely get added to the docs.

Technically, you could make a custom decorator for req and res and get pipes to run for them.

export const ReqDec = createParamDecorator(
  (data: unknown, ctx: ExecutionContext) => {
    const request = ctx.switchToHttp().getRequest();
    return request;
  },
);

And then use it as @ReqDec()