如何使用超类调用键入 Python mixin？

Question

我正尝试在我的项目中使用，但我无法通过 mypy 检查。当前代码：

class DynamicFieldsMixin(Serializer):
    context: Dict[str, Any]

    def get_field_names(
        self, declared_fields: OrderedDict, info: FieldInfo
    ) -> Set[str]:
        field_names: Set[str] = self.context.get(
            "fields",
            super().get_field_names(declared_fields, info)
        )
        return field_names

从 rest_framework.serializers.Serializer 继承似乎很奇怪，我想知道是否有办法避免这种情况，因为它应该混合到实际的 Serializer 类中。仅删除超类会导致此错误：

error: "get_field_names" undefined in superclass

mypy配置：

[mypy]
check_untyped_defs = true
disallow_untyped_defs = true
ignore_missing_imports = true
no_implicit_optional = true
warn_redundant_casts = true
warn_return_any = true
warn_unused_ignores = true

Answer 1

您可以引入基数 class 仅用于类型检查：

import typing
from typing import Any, Dict, List, Mapping, TypeVar
from rest_framework.fields import Field
from rest_framework.serializers import ModelSerializer
from rest_framework.utils.model_meta import FieldInfo


if typing.TYPE_CHECKING:
    _Base = ModelSerializer
else:
    _Base = object


class DynamicFieldsMixin(_Base):
    context: Dict[str, Any]

    def get_field_names(self, declared_fields: Mapping[str, Field], info: FieldInfo) -> List[str]:
        field_names = super().get_field_names(declared_fields, info)
        # Revealed type is 'builtins.list[builtins.str]'
        reveal_type(field_names)
        return field_names

如何使用超类调用键入 Python mixin？

How to type Python mixin with superclass calls?

python

python-3.x

mypy