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Description
Initial Checks
- I confirm that I'm using Pydantic V2
Description
Given a function with a model_serializer decorator, and that function calls an instance method on the model, when I attempt to run mypy with the pydantic plugin enabled, then I incorrectly see two errors from mypy regarding the types to the call of the instance method.
demo.py:21: error: Missing positional argument "value" in call to "_calculate_is_hot" of "TemperatureModel" [call-arg]
demo.py:21: error: Argument 1 to "_calculate_is_hot" of "TemperatureModel" has incompatible type "int"; expected "TemperatureModel" [arg-type]
demo.py:26: error: Missing positional argument "value" in call to "_calculate_is_hot" of "TemperatureModel" [call-arg]
demo.py:26: error: Argument 1 to "_calculate_is_hot" of "TemperatureModel" has incompatible type "int"; expected "TemperatureModel" [arg-type]Given the same as above, when I run mypy without the pydantic plugin enabled, mypy evaluates the example correctly with no issues.
Example Code
from typing import Literal
from pydantic import BaseModel, model_serializer
class TemperatureModel(BaseModel):
unit: Literal["C", "F"]
value: int
def _calculate_is_hot(self, value: int) -> bool:
if self.unit == "F":
return value > 100
return value > 38
@model_serializer(when_used="json")
def serialize_model(self) -> dict[str, int | str | bool]:
var: int = self.value
if self.unit == "F":
return {
"unit": "C",
"value": int((self.value - 32) / 1.8),
"is_hot": self._calculate_is_hot(var),
}
return {
"unit": self.unit,
"value": self.value,
"is_hot": self._calculate_is_hot(var),
}
temperature = TemperatureModel(unit="F", value=212)
print(temperature.model_dump_json())Python, Pydantic & OS Version
pydantic version: 2.9.2
pydantic-core version: 2.23.4
pydantic-core build: profile=release pgo=false
install path: /Users/drewayling/Workspace/apps.autosar.authoring-tool/.venv/lib/python3.12/site-packages/pydantic
python version: 3.12.6 (main, Sep 6 2024, 19:03:47) [Clang 15.0.0 (clang-1500.3.9.4)]
platform: macOS-15.0.1-x86_64-i386-64bit
related packages: pydantic-extra-types-2.9.0 typing_extensions-4.12.2 mypy-1.11.1
commit: unknown