serializable_helper.py

import inspect
import json
from typing import Dict, TypeVar


SerializableDataType = TypeVar(
    "SerializableDataType",
    bound="Serializable"
)


class Serializable:
    default_cls_encoder = json.JSONEncoder
    default_cls_decoder = json.JSONDecoder

    @classmethod
    def from_json(cls, content: str, **kwargs) -> SerializableDataType:
        kwargs["cls"] = kwargs.pop("json_cls", cls.default_cls_decoder)
        instance_kwargs = json.loads(content, **kwargs)
        return cls(**instance_kwargs)
    
    @classmethod
    def from_file(cls, filename: str, **kwargs) -> SerializableDataType:
        with open(filename, "r") as file:
            return cls.from_json(content=file.read(), **kwargs)

    @classmethod
    def _get_init_arglist(cls):
        return inspect.getfullargspec(cls).args
        
    def to_dict(self, error_if_not_exists: bool = False) -> Dict:
        return {
            arg: getattr(self, arg) if error_if_not_exists else \
                 getattr(self, arg, None)
            for arg in self._get_init_arglist()
            if arg != "self"
        }

    def to_json(self, **kwargs) -> str:
        dictionary = self.to_dict()
        kwargs["cls"] = kwargs.pop("json_cls", self.default_cls_encoder)
        return json.dumps(dictionary, **kwargs)