import dataclasses
import dacite
import typing


@dataclasses.dataclass
class OptionalDataclass:
    text1: typing.Optional[str]


@dataclasses.dataclass
class UnionDataclass:
    text2: str | None


if __name__ == '__main__':
    d1 = {"text1": None}
    # In order to reproduce this bug:
    # 1. this needs to be called first
    dacite.from_dict(OptionalDataclass, d1)

    # 2. this field has to be non None
    d2 = {"text2": "abc"}

    # 3. config with cast needs to be provided
    # (content of cast array does not matter, as it only is necessary to trigger
    #   for cast_type in config.cast
    # in dacite/core.py)
    c = dacite.Config(cast=[int])

    # then below fails
    res = dacite.from_dict(UnionDataclass, d2, config=c)

    # without either of 1-3 from above steps, final from_dict will work as expected

/usr/local/lib/python3.10/site-packages/dacite/core.py:64: in from_dict
    value = _build_value(type_=field_type, data=field_data, config=config)
/usr/local/lib/python3.10/site-packages/dacite/core.py:101: in _build_value
    if is_subclass(type_, cast_type):
/usr/local/lib/python3.10/site-packages/dacite/types.py:174: in is_subclass
    if is_generic_collection(sub_type):
/usr/local/lib/python3.10/site-packages/dacite/types.py:147: in is_generic_collection
    origin = extract_origin_collection(type_)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

collection = str | None

    def extract_origin_collection(collection: Type) -> Type:
        try:
            return collection.__extra__
        except AttributeError:
>           return collection.__origin__
E           AttributeError: 'types.UnionType' object has no attribute '__origin__'

if __name__ == '__main__':
    is_generic(typing.Optional[str])
    is_generic_collection(str | None)

if __name__ == '__main__':
    is_generic_collection(str | None)