I have the following dataclass:

@dataclass
class Image:content_type: strdata: bytes = b''id: str = ""upload_date: datetime = Nonesize: int = 0def to_dict(self) -> Dict[str, Any]:result = {}if self.id:result['id'] = self.idif self.content_type:result['content_type'] = self.content_typeif self.size:result['size'] = self.sizeif self.upload_date:result['upload_date'] = self.upload_date.isoformat()return result

Is there any way to simplify to_dict method? I don't want to list all of the fields using if.

As suggested by meowgoesthedog, you can use asdict and filter the result to skip falsy values:

from dataclasses import dataclass, asdict
from datetime import datetime
from typing import Dict, Any@dataclass
class Image:content_type: strdata: bytes = b''id: str = ""upload_date: datetime = Nonesize: int = 0def to_dict(self) -> Dict[str, Any]:return {k: v for k, v in asdict(self).items() if v}print(Image('a', b'b', 'c', None, 0).to_dict())
# {'content_type': 'a', 'data': b'b', 'id': 'c'}