Mypy issues with BaseSettings and SettingsConfigDict - v2

[axeng]

It seems that mypy has some issues with the new BaseSettings.
I did the same tests with pydantic v1 and it did not throw these errors.

Using this example:

from pydantic_settings import BaseSettings, SettingsConfigDict

class TestSettings(BaseSettings):
    model_config = SettingsConfigDict(env_file=".env")

    test_field: str

settings = TestSettings()

Mypy is throwing the following:

test.py:4: error: Incompatible types (expression has type "str", TypedDict item "env_file" has type "Path | list[Path] | tuple[Path, ...] | None")  [typeddict-item]
test.py:8: error: Missing named argument "test_field" for "TestSettings"  [call-arg]
Found 2 errors in 1 file (checked 1 source file)

Here the Mypy configuration I am using:

[tool.mypy]
ignore_missing_imports = true
plugins = [
    "pydantic.mypy",
]
disallow_untyped_defs = true
disallow_any_unimported = true
no_implicit_optional = true
check_untyped_defs = true
warn_unused_ignores = true
show_error_codes = true
warn_unreachable = true

---

pydantic version: 2.0
pydantic-core version: 2.0.1
pydantic-settings version: 2.0
mypy version: 1.4.1

Selected Assignee: @dmontagu

[hramezani]

Thanks @axeng for reporting this issue.

The first error:

test.py:4: error: Incompatible types (expression has type "str", TypedDict item "env_file" has type "Path | list[Path] | tuple[Path, ...] | None") [typeddict-item]

Can be fixed by including str in the allowed type for env_file config.

The second error:

test.py:8: error: Missing named argument "test_field" for "TestSettings" [call-arg]

There was some logic related to setting management in V1 mypy plugin which has been removed because settings management is not part of Pydantic V2.
I think we can create a mypy plugin for pydantic-settings that inherit from Pydantic V2 mypy plugin and add specific logic for pydantic-settings.

What do you think @samuelcolvin @dmontagu ?