Dataclasses JSON

This library provides a simple API for encoding and decoding dataclasses to and from JSON.

It's recursive (see caveats below), so you can easily work with nested dataclasses.

In addition to the supported types in the py to JSON table, any arbitrary Collection type is supported (they are encoded into JSON arrays, but decoded into the original collection types).

The latest release is compatible with both Python 3.7 and Python 3.6 (with the dataclasses backport).

Quickstart

pip install dataclasses-json

from dataclasses import dataclass
from dataclasses_json import DataClassJsonMixin

@dataclass
class MyDataClass(DataClassJsonMixin):
    name: str

my_dataclass_instance = MyDataClass('example')

# Encoding to JSON
some_json_string = my_dataclass_instance.to_json()

# Decoding from JSON
MyDataClass.from_json(some_json_string)

A larger example

from dataclasses import dataclass
from dataclasses_json import DataClassJsonMixin
from typing import List


@dataclass(frozen=True)
class Minion(DataClassJsonMixin):
    name: str


@dataclass(frozen=True)
class Boss(DataClassJsonMixin):
    minions: List[Minion]

boss = Boss([Minion('evil minion'), Minion('very evil minion')])
boss_json = """
{
    "minions": [
        {
            "name": "evil minion"
        },
        {
            "name": "very evil minion"
        }
    ]
}
""".strip()

assert boss.to_json(indent=4) == boss_json
assert Boss.from_json(boss_json) == boss

Caveats

Data Classes that contain forward references (e.g. recursive dataclasses) are not currently supported.