JSON Dataclasses

Typed JSON dataclasses for Python 3.9+

Check out the docs

Installation

pip install jsondataclasses

Usage

from datetime import date
from typing import Literal, Optional

from jsondataclasses import jsondataclass, jsonfield


def parse_date(date_string: str) -> date:
    return date.fromisoformat(date_string.replace(".", "-"))


@jsondataclass
class Car:
    make: Literal["Ford", "Renault", "Volkswagen"] = jsonfield("carMake")
    model: str = jsonfield("model")
    manufactured_at: date = jsonfield("dateOfManufacture", parse_date)
    num_of_wheels: Optional[int] = jsonfield("numberOfWheels", default_value=4)


car = Car({
    "carMake": "Ford",
    "model": "Focus",
    "dateOfManufacture": "2018.03.14"
})
print(car)  # Car(make='Ford', model='Focus', manufactured_at=datetime.date(2018, 3, 14), num_of_wheels=4)

Class field types can be any primitive type (eg. str, int, datetime), a variadic generic (eg. list[str], Optional[int], Literal["hello", "world"]), or even another jsondataclass. The default_value argument of jsonfield will be used if the specified key is not found in the dictionary and the type of the class field is not Optional[...]. In this case, the value of default_value will be passed to the supplied parser function.