Example of using dataclass-json nested inheritance attributes

dataclass_json_inherit.py

import dataclasses

import dataclasses_json
from dataclasses_json import DataClassJsonMixin


@dataclasses.dataclass(frozen=True)
class Value(DataClassJsonMixin):
    value_type: str = dataclasses.field(init=False, default="unknown", metadata=dataclasses_json.config(field_name="type"))

    @staticmethod
    def value_decoder(content: any) -> 'Value':
        if isinstance(content, dict) and "type" in content:
            if content["type"] == "str":
                return StringValue.from_dict(content)
            elif content["type"] == "int":
                return IntValue.from_dict(content)
            elif content["type"] == "unknown":
                return Value.from_dict(content)
        raise NotImplementedError(f"Unknown value: {content}")


@dataclasses.dataclass(frozen=True)
class StringValue(Value, DataClassJsonMixin):
    value: str
    value_type: str = dataclasses.field(init=False, default="str", metadata=dataclasses_json.config(field_name="type"))


@dataclasses.dataclass(frozen=True)
class IntValue(Value, DataClassJsonMixin):
    value: int
    value_type: str = dataclasses.field(init=False, default="int", metadata=dataclasses_json.config(field_name="type"))


@dataclasses.dataclass(frozen=True)
class Data(DataClassJsonMixin):
    name: str
    value: Value = dataclasses.field(metadata=dataclasses_json.config(decoder=Value.value_decoder))


if __name__ == '__main__':
    obj_1 = Data(
        name="data",
        value=StringValue("text")
    )
    obj_2 = Data(
        name="data",
        value=IntValue(12345)
    )

    dict_1 = obj_1.to_dict()
    dict_2 = obj_2.to_dict()

    # {'name': 'data', 'value': {'type': 'str', 'value': 'text'}}
    print(dict_1)
    # {'name': 'data', 'value': {'type': 'int', 'value': 12345}}
    print(dict_2)

    # Data(name='data', value=StringValue(value_type='str', value='text'))
    print(Data.from_dict(dict_1))
    # Data(name='data', value=IntValue(value_type='int', value=12345))
    print(Data.from_dict(dict_2))