cattrs.preconf.tomlkit doesn't support TOML date type

[RazerM]

from datetime import date, datetime

import tomlkit
from attrs import define
from cattrs.preconf.tomlkit import make_converter


@define
class Event:
    event_date: date
    event_datetime: datetime


TOML_INPUT = """\
event_date = 2025-12-16
event_datetime = 2025-12-16T20:00:00
"""


def main() -> None:
    converter = make_converter()

    parsed = tomlkit.loads(TOML_INPUT)
    print(converter.structure(parsed, Event))


if __name__ == "__main__":
    main()

  + Exception Group Traceback (most recent call last):
  |   File "cattrs_tomlkit_issue.py", line 28, in <module>
  |     main()
  |   File "cattrs_tomlkit_issue.py", line 24, in main
  |     converter.structure(parsed, Event)
  |   File ".venv/lib/python3.12/site-packages/cattrs/converters.py", line 589, in structure
  |     return self._structure_func.dispatch(cl)(obj, cl)
  |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |   File "<cattrs generated structure __main__.Event>", line 14, in structure_Event
  | cattrs.errors.ClassValidationError: While structuring Event (1 sub-exception)
  +-+---------------- 1 ----------------
    | Traceback (most recent call last):
    |   File "<cattrs generated structure __main__.Event>", line 5, in structure_Event
    |   File ".venv/lib/python3.12/site-packages/cattrs/preconf/tomlkit.py", line 73, in <lambda>
    |     converter.register_structure_hook(date, lambda v, _: date.fromisoformat(v))
    |                                                          ^^^^^^^^^^^^^^^^^^^^^
    | TypeError: fromisoformat: argument must be str
    | Structuring class Event @ attribute event_date
    +------------------------------------

[Tinche]

Ooph, got it. Let me see about fixing this.

[Tinche]

I think I got this in #708

In the mean time, you can work around it by overriding the hook:

from datetime import date

converter.register_structure_hook(
    date, lambda v, _: v if isinstance(v, date) else date.fromisoformat(v)
)