ReturnDict throws KeyError when part of dataclass and dataclasses.asdict() called

[LiamClarkeNZ]

ReturnDict's constructor expects the kwarg serializer to always be provided, and if not an exception is thrown.

So when the code in dataclasses.asdict that handles dict elements of a dataclass tries to copy it using the constructor, it fails.

This has also bitten us when using further serializers (Avro etc.) that also use the same approach to copy a subclass of dict.

Reproduction test case:

from typing import Dict, Any

import dataclasses
from django.test import SimpleTestCase
from rest_framework.utils.serializer_helpers import ReturnDict


@dataclasses.dataclass
class Example:
    some_dict: Dict[Any, Any]


class TestReturnDictInDataClass(SimpleTestCase):

    def test_kwargs_error(self):
        rdict = ReturnDict(serializer=None, a=1, b=2)
        example = Example(some_dict=rdict)
        self.assertRaises(KeyError, lambda: dataclasses.asdict(example))

Suggestion

Given that providing a value of None for serializer doesn't break the instantiation of ReturnDict, perhaps the pop could be replaced by a more forgiving approach?

[auvipy]

I would be open to review a PR with a proper failing testcase and a draft solution which don't break any existing right behavior

[LiamClarkeNZ]

Cheers, will flick up a draft PR soon :)

[dfm88]

Any update on this? thanks

[LiamClarkeNZ]

Not from my end sorry, I haven't had the time to do so yet, but will give it a crack soon.

[jamesliberatii]

This affects ReturnList as well, see: goauthentik/authentik#9430