Pipes

The most common pipe used with and provided by Nest.js is the ValidationPipe. This pipe, however, cannot be used with microservice handlers because it throws exceptions extending HttpException. All exceptions thrown in a microservice must extend RpcException. To fix this, we can extend the ValidationPipe, catch the HttpException, and throw an RpcException.

@Injectable()
export class RpcValidationPipe extends ValidationPipe implements PipeTransform<any> {
    public async transform(value: any, metadata: ArgumentMetadata) {
        try {
            await super.transform(value, metadata);
        } catch (error) {
            if (error instanceof BadRequestException) {
                throw new RpcValidationException();
            }

            throw error;
        }

        return value;
    }
}

Before we can use the ValidationPipe, we have to create a class that describes the format of the data our microservice method expects.

class CreateUserRequest {
      @IsEmail...