Flask-SQLAlchemy 中带有连接查询的不明确列名

Question

表设置：

我的列名不明确？...在​​我的第一个表中，sqlalchemy 加入的列不存在。

但是，在sqlite浏览器中，已经建立了关系。

class Parent:
    childs = db.relationship('Child',
                                   backref=db.backref('parent', lazy='joined'),
                                   lazy='select',
                                   )
class Child:
     parents = db.column(db.Integer, db.ForeignKey='parents.id')
     siblings = db.relationship('Sibling', backref=db.backref'child', lazy='select')

class Sibling:
     childs = db.column(db.Integer, db.ForeignKey='child.id')

查询：

def json_join():
   data = db.session.query(Parent, Child, Sibling)\
    .join(Parent)\
    .join(Child)\
    .join(Sibling)\
    .filter(Parent.id == Child.id == Sibling.id)\
    .all()
   return data

错误： 不明确的列名 child.id

我认为： 父列中的关系不会为子关系创建列？所以没有加入...

Answer 1

查看文档以了解父子关系的一对多关系： https://docs.sqlalchemy.org/en/14/orm/basic_relationships.html#many-to-one

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

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

另请参阅有关儿童和兄弟姐妹（作为父母和儿童）的多对多关系的文档：https://docs.sqlalchemy.org/en/14/orm/basic_relationships.html#many-to-many

association_table = Table('association', Base.metadata,
    Column('left_id', Integer, ForeignKey('left.id')),
    Column('right_id', Integer, ForeignKey('right.id'))
)

class Parent(Base):
    __tablename__ = 'left'
    id = Column(Integer, primary_key=True)
    children = relationship(
        "Child",
        secondary=association_table,
        back_populates="parents")

class Child(Base):
    __tablename__ = 'right'
    id = Column(Integer, primary_key=True)
    parents = relationship(
        "Parent",
        secondary=association_table,
        back_populates="children")