Dependencies imported from file with python annotations don't work #446
Description
Describe the bug
When there is a file that contains python annotations import at the top and contains some async function returning parameters dependency injection doesn't work.
To Reproduce
Create file deps.py:
from __future__ import annotation
async def test(foo: Optional[str] = None):
return fooAnd then in the other file containing route definition:
from .deps import test
@api.get("/foo")
async def foo_route(foo: Optional[str] = Depends(test)):
return NoneTrying to run the app with such configuration results in error:
...
File "/Users/user/.local/share/virtualenvs/pilgrim-api-A9HJbenQ/lib/python3.7/site-packages/fastapi/dependencies/utils.py", line 179, in get_dependant
param_field = get_param_field(param=param, default_schema=params.Query)
File "/Users/user/.local/share/virtualenvs/pilgrim-api-A9HJbenQ/lib/python3.7/site-packages/fastapi/dependencies/utils.py", line 265, in get_param_field
schema=schema,
File "/Users/user/.local/share/virtualenvs/pilgrim-api-A9HJbenQ/lib/python3.7/site-packages/pydantic/fields.py", line 112, in __init__
self.prepare()
File "/Users/user/.local/share/virtualenvs/pilgrim-api-A9HJbenQ/lib/python3.7/site-packages/pydantic/fields.py", line 178, in prepare
self._populate_validators()
File "/Users/user/.local/share/virtualenvs/pilgrim-api-A9HJbenQ/lib/python3.7/site-packages/pydantic/fields.py", line 269, in _populate_validators
*(get_validators() if get_validators else list(find_validators(self.type_, self.model_config))),
File "/Users/user/.local/share/virtualenvs/pilgrim-api-A9HJbenQ/lib/python3.7/site-packages/pydantic/validators.py", line 470, in find_validators
raise RuntimeError(f'error checking inheritance of {type_!r} (type: {display_as_type(type_)})') from e
RuntimeError: error checking inheritance of 'Optional[str]' (type: str)
Expected behavior
It runs and works.
Environment:
- OS: macOS
- FastAPI Version: 0.35
- Python: 3.7.3