Dataclasses with FrozenSet members fail upon declaration. #745
Description
Feature Request
Please complete:
- OS: Ubuntu 16.04
- Python version
import sys; print(sys.version): 3.7.3 - Pydantic version
import pydantic; print(pydantic.VERSION): 0.32.1
When creating a pydantic dataclass that has a FrozenSet member, initialization fails in the @dataclass decorator.
For example,
from typing import FrozenSet
from pydantic.dataclasses import dataclass
@dataclass
class MyDataClass:
foo: FrozenSet[str]
...will fail with an assertion error:
Traceback (most recent call last):
File "<input>", line 1, in <module>
File "pydantic/dataclasses.py", line 125, in pydantic.dataclasses.dataclass.wrap
File "pydantic/dataclasses.py", line 87, in pydantic.dataclasses._process_class
File "pydantic/main.py", line 710, in pydantic.main.create_model
File "pydantic/main.py", line 228, in pydantic.main.MetaModel.__new__
File "pydantic/fields.py", line 145, in pydantic.fields.Field.infer
File "pydantic/fields.py", line 122, in pydantic.fields.Field.__init__
File "pydantic/fields.py", line 187, in pydantic.fields.Field.prepare
File "pydantic/fields.py", line 252, in pydantic.fields.Field._populate_sub_fields
AssertionErrorLooking in the pydantic source code, it looks like this has to do with how it determines the type of the field. Specifically, the issue is that FrozenSet, somewhat counter-intuitively, does not appear to be a subtype of Set:
>>> from typing import FrozenSet, Set
>>> issubclass(FrozenSet, Set)
False It looks like this if-else block has to be amended with a specific case for FrozenSet.