如何从具有关系的表中检索数据-多对多（SQLAlchemy）？

Question

I have two models with a many to many relationship (SQLAlchemy):

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",
                    backref="parents")

class Child(Base):
    __tablename__ = 'right'
    id = Column(Integer, primary_key=True)

Get "all parents of one (second on the list) the child" I can that way:

parents = session.query(Parent).filter(Parent.children.any(id=2))

And how to get "all the children of a parent"?

Answer 1

Any of the below should do:

# 1.
children = session.query(Child).filter(Child.parents.any(Parent.id==??))
# 2.
children = session.query(Child).join(Parent, Child.parents).filter(Parent.id == 99)
# 3.
my_parent = session.query(Parent).get(2)
children = session.query(Child).with_parent(my_parent).all()