python - SQLAlchemy一对一，在每个表中存储外键？

Question

笼子代码和邓氏号码之间存在一对一的关系。

我已经建立了看起来像这样的关系，我在每个相应的表上存储了一个外键。

class Cage(Base):
    __tablename__ = 'DimCage'

    id = Column(Integer, primary_key=True)
    cage = Column(String(8), unique=True, nullable=False)
    duns_id = Column(Integer, ForeignKey('DimDuns.id'))

    duns = relationship('Duns', uselist=False, back_populates='cage')


class Duns(Base):
    __tablename__ = 'DimDuns'

    id = Column(Integer, primary_key=True)
    duns = Column(String(10), unique=True, nullable=False)
    dunsInt = Column(Integer, unique=True, nullable=False)
    cage_id = Column(Integer, ForeignKey('DimCage.id'))

    cage = relationship('Cage', uselist=False, back_populates='duns')

当我创建表时出现以下错误，如何设置外键以便在两个表上保留引用？

sqlalchemy.exc.AmbiguousForeignKeysError: Can't determine join between 'DimCage' and 'DimDuns'; tables have more than one foreign key constraint relationship between them. Please specify the 'onclause' of this join explicitly.

并且在处理上述异常的过程中，发生了另一个异常:

sqlalchemy.exc.AmbiguousForeignKeysError: Could not determine join condition between parent/child tables on relationship Cage.duns - there are multiple foreign key paths linking the tables. Specify the 'foreign_keys' argument, providing a list of those columns which should be counted as containing a foreign key reference to the parent table.

Answer 1

我相信您只需要存储一个外键即可建立一对一的关系。
请参阅https://docs.sqlalchemy.org/en/13/orm/basic_relationships.html#one-to-one

您不应以这种方式丢失任何数据访问权限。如果您从 Cage 中删除 duns_id 列，您现在可以通过 cage.duns.id 而不是 cage.duns_id< 访问 ID/.