Python dataclass inverse of asdict

fromdict.py

from dataclasses import is_dataclass, fields
from typing import TypeVar

T = TypeVar("T")


def fromdict(d: dict, ty: type[T]) -> T:
    assert is_dataclass(ty)
    for field in fields(ty):
        if field.name in d:
            if is_dataclass(field.type):
                assert isinstance(d[field.name], dict)
                d[field.name] = fromdict(d[field.name], field.type)
    return ty(**d)


from dataclasses import dataclass, asdict


@dataclass
class Foo:
    a: int = 5
    b: int = 6


@dataclass
class Bar:
    foo: Foo
    c: int = 7


b1 = Bar(foo=Foo())
d = asdict(b1)
b2 = fromdict(d, Bar)

print(b1, b2)