2

这是与 backref 和删除级联关系的简单示例。

class Parent(Base):
    __tablename__ = 'parent'
    id = Column(Integer, primary_key=True)

class Child(Base):
    __tablename__ = 'child'
    id = Column(Integer, primary_key=True)
    parent_id = Column(Integer, ForeignKey('Parent.id'))
    parent = relation(
        'Parent',
        backref=backref('children', cascade='delete, delete-orphan')
    )

需要将一些孩子从一个父母重新分配给另一个父母,然后需要删除另一个父母,但是 sqlalchemy 在删除父母之前会删除孩子......

p1 = Session.query(Parent).get(...)
p2 = Session.query(Parent).get(...)

p1.children.extend(p2.children)
Session.delete(p2)
Session.commit()

日志:

... [worker 0] UPDATE child SET parent_id=%(parent_id)s WHERE child.id = %(child_id)s
...
... [worker 0] DELETE FROM child WHERE child.id = %(id)s
...
... [worker 0] DELETE FROM parent WHERE parent.id = %(id)s
...
... [worker 0] COMMIT

需要以某种方式将孩子与另一个父母分开......

4

1 回答 1

0

我可以建议的唯一解决方案是:

p1 = Session.query(Parent).get(...)
p2 = Session.query(Parent).get(...)

for child in p2.children[:]:
    child.parent = p1

Session.delete(p2)
Session.commit()
于 2012-11-08T08:54:32.137 回答