[英]Python: How to specify function return type in a mixin method
[英]How to type Python mixin with superclass calls?
我试图在我的项目中使用这个答案中的FieldMixin
,但我无法让它通过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,因为它意味着要混合到实际的Serializer
类中。 仅删除超类会导致此错误:
错误:“get_field_names”在超类中未定义
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
您可以仅出于类型检查的目的引入基类:
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
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