mypy 无法识别具有 hybrid_property 的 SQLAlchemy 列答案

【问题标题】：mypy doesn't recognize SQLAlchemy columns with hybrid_propertymypy 无法识别具有 hybrid_property 的 SQLAlchemy 列
【发布时间】：2022-12-22 15:08:38
【问题描述】：

我正在尝试将 mypy 与 SQLAlchemy 一起使用。为了验证/修改特定的列值（在本例中为email），SQLAlchemy official document提供了hybrid_property装饰器。

问题是，mypy 无法正确识别 EmailAddress 类构造函数，它给出：

email_address.py:31: error: Unexpected keyword argument "email" for "EmailAddress"; did you mean "_email"?

我如何告诉 mypy 识别这些列？

from typing import TYPE_CHECKING

from sqlalchemy import Column, Integer, String
from sqlalchemy.ext.declarative import declarative_base

# I don't even like the following statements just for setter
if TYPE_CHECKING:
    hybrid_property = property
else:
    from sqlalchemy.ext.hybrid import hybrid_property

Base = declarative_base()


class EmailAddress(Base):
    __tablename__ = "email_address"

    id = Column(Integer, primary_key=True)

    _email = Column("email", String)

    @hybrid_property
    def email(self):
        return self._email

    @email.setter
    def email(self, email):
        self._email = email


EmailAddress(email="foobar@example.com")
# email_address.py:31: error: Unexpected keyword argument "email" for "EmailAddress"; did you mean "_email"?

我正在使用以下软件包：

SQLAlchemy==1.4.35
mypy==0.942
mypy-extensions==0.4.3
sqlalchemy2-stubs==0.0.2a22

【问题讨论】：

到目前为止，您是否找到了让它发挥作用的方法？
@Welyweloo，不。在对象初始化后分配属性“技术上”可以避免 mypy 错误，但这与我想要的相差甚远，例如 email = EmailAddress() 然后 email.email = "foobar@example.com"
@Welyweloo，我在下面写下了我的答案。

标签： python sqlalchemy mypy

【解决方案1】：

好的，看来我终于找到了解决问题的方法。

这让我想起了here 中讨论的数据类/属性装饰器之间的不合作行为。

我最终将 EmailAddress 类分成 2 个：

在基类上使用 @dataclass 装饰器以指示构造函数选项。

覆盖email 属性，这样 mypy 就不会抱怨重新定义。

from dataclasses import dataclass
from typing import TYPE_CHECKING, Optional

from sqlalchemy import Column, Integer, String, Table
from sqlalchemy.orm import registry

mapper_registry: registry = registry()

# I don't even like the following statements just for setter
if TYPE_CHECKING:
    hybrid_property = property
else:
    from sqlalchemy.ext.hybrid import hybrid_property


@dataclass
@mapper_registry.mapped
class EmailAddressBase:
    __tablename__ = "email address"

    id: int = Column(Integer, primary_key=True)
    email: Optional[str] = None


class EmailAddress(EmailAddressBase):
    _email = Column("email", String)

    @hybrid_property
    def email(self):
        return self._email

    @email.setter
    def email(self, email):
        self._email = email


email = EmailAddress(email="foobar@example.com")
print(email.email)

【讨论】：