UUID typing hints of Pydantic 1.8 are inaccurate #2418
Description
Checks
- I added a descriptive title to this issue
- I have searched (google, github) for similar issues and couldn't find anything
- I have read and followed the docs and still think this is a bug
Bug
It appears commit 7da04d9 introduces a type erasure on UUID1/UUID2/UUID3/UUID4 that makes them all Union[UUID, str], losing the strict inheritance from UUID.
Now:
from uuid import UUID, uuid4
from pydantic import UUID4, BaseModel
def expects_any_uuid(arg: UUID):
pass
class MyModel(BaseModel):
my_uuid: UUID4
# While these two are now correct in regards to type checking:
# (they were triggering typing errors in v1.7)
MyModel(my_uuid=uuid4()) # 1
MyModel(my_uuid="5259A9AA-D1FD-4D0A-B17D-87803904C233") # 2
# These two calls are not correct anymore:
expects_any_uuid(MyModel(my_uuid=uuid4()).my_uuid) # 3
expects_any_uuid(uuid4()) # 4
# Type checking like MyPy would say something along the following:
# Argument 1 to "expects_any_uuid" has incompatible type "Union[UUID, str]"; expected "UUID"I would argue that making # 2 clear the typing error from 1.7 is nice to have, but we could already use something like a # type: ignore comment to explicitly tell type-checking, which was acceptable since some strs are not UUID4s, and as such it makes sense to have to explicitly silent a warning here.
Same with # 1, since its type is “erased” to a generic UUID, we would need to check again that it is indeed a v4 UUID.
On the other hand, a UUID4 is always a UUID, so # 3 and # 4 should never trigger a static typing error.
I don't have a solution to make all examples # 1 to # 4 from above work, so instead I'm opening an issue here in hopes someone would have a solution.
Output of python -c "import pydantic.utils; print(pydantic.utils.version_info())":
pydantic version: 1.8
pydantic compiled: True
install path: <redacted>/venv/lib/python3.9/site-packages/pydantic
python version: 3.9.2 (default, Feb 19 2021, 17:43:04) [Clang 12.0.0 (clang-1200.0.32.29)]
platform: macOS-11.2.1-x86_64-i386-64bit
optional deps. installed: ['dotenv', 'email-validator', 'typing-extensions']