Nestjs ClassSerializerInterceptor doesn't work

Question

I want ClassSerializerInterceptor to make my response body match response type, currently it doesn't work and still returns all the fields that are returned from function. Example of my response DTO:

export class SignedInUserDTO extends PartialType(
  PickType(User, ['id', 'email', 'role']),
) {
  @IsString()
  accessToken: string;
}

For my DTO I also tried to attach @Exclude(), but this had no effect.

Controller:

 @Post('sign-in')
  async signUp(@Body() signInUserDto: SignInUserDTO): Promise<SignedInUserDTO> {
    return this.authService.signIn(signInUserDto);
  }

How I set up interceptor in main.ts:

  app.useGlobalInterceptors(new ClassSerializerInterceptor(app.get(Reflector)));

I also tried to attach it directly to route like this:

@UseInterceptors(ClassSerializerInterceptor)

But neither method works. I really have no clue what is wrong here, any thoughts?

UPDATE:

I've played around for a few more hours, it's working with another route which just returns user from database, fields marked with @Exclude() are not returned, which is correct, yet it still doesn't work for other routes, even using plainToInstance().

Answer 1

So this is happening because plain object is returned from response, but ClassSerializerInterceptor can work only with classes.

I used approach like this: https://gist.github.com/ibayazit/dee57afc274297490e7265bcf4da63ab

And now for every route that returns plain object I attach @Serialize() decorator.

Still I'd prefer to set this up on global level, any suggestions on that are higly appreciated.