serdejson.py

from __future__ import annotations
from dataclasses import dataclass, asdict, is_dataclass
from typing import Any
from typing_extensions import dataclass_transform  # pip install typing-extensions
import dacite  # pip install dacite
import json

@dataclass_transform(kw_only_default=True)
class SerdeJson:
    def __init_subclass__(cls):
        _ = dataclass(cls)

    @classmethod
    def from_dict(cls, data: dict[str, Any]):
        return dacite.from_dict(cls, data)

    @classmethod
    def from_json(cls, data: str):
        return cls.from_dict(json.loads(data))

    def to_dict(self):
        assert is_dataclass(self)  # Suppress type error
        return asdict(self)

    def to_json(self):
        return json.dumps(self.to_dict())


if __name__ == "__main__":
    class ExampleClass(SerdeJson):
        name: str
        age: int
        is_old: bool

        def birthday(self):
            self.age += 1
            self.is_old = True

    a = ExampleClass.from_json(r'{"name": "Kris", "is_old": false, "age": 30}')
    a.birthday()
    assert(a.to_json() == r'{"name": "Kris", "age": 31, "is_old": true}')