SQLAlchemy循环一对一的关系

Question

我试图与SQLAlchemy建立一个循环的一对一关系(不确定正确的术语是什么),看起来如下:

class Parent(Base):
    __tablename__ = 'parents'
    id = db.Column(Integer, primary_key=True)
    child_id = db.Column(db.Integer,db.ForeignKey("children.id", use_alter=True))
    child = db.relationship("Child",
                        uselist=False,
                        foreign_keys=[child_id],
                        post_update=True)

class Child(Base):
    __tablename__ = 'children'
    id = db.Column(db.Integer, primary_key=True)
    parent_id = db.Column(db.Integer, db.ForeignKey("parents.id"))
    user = db.relationship("Parent",
                       uselist=False,
                       foreign_keys=[parent_id])

一切正常,直到我尝试db.drop_all(),我得到一个错误的sqlalchemy.sql.schema.ForeignKeyConstraint name是None.在尝试建立这种循环的一对一关系时,我做错了吗？我真的希望能够只查询单个列来获取另一个列的id,因此循环引用.

Answer 1

来自SQLAlchemy文档:

class Parent(Base):
    __tablename__ = 'parent'
    id = Column(Integer, primary_key=True)
    child = relationship("Child", uselist=False, back_populates="parent")

class Child(Base):
    __tablename__ = 'child'
    id = Column(Integer, primary_key=True)
    parent_id = Column(Integer, ForeignKey('parent.id'))
    parent = relationship("Parent", back_populates="child")

然后你可以整天使用Parent.child或Child.parent