The default relationship cascade settings will do it for you. Here I made
them explicit.
class Parent(Base):
__tablename__ = 'parent'
id = Column(Integer, primary_key=True)
class Child(Base):
__tablename__ = 'child'
id = Column(Integer, primary_key=True)
p_id = Column(Integer, ForeignKey(Parent.id))
parent = relation(Parent, backref=backref('children',
cascade="save-update,merge"))
sess.add(Parent(children=[Child(),Child()]))
sess.commit()
p = sess.query(Parent).first()
sess.delete(p)
sess.commit()
--
Mike Conley
On Fri, Aug 19, 2011 at 12:10 PM, Mark Erbaugh <[email protected]> wrote:
> I have a table that has a foreign key field that is optional. IOW, the
> current row may be linked to at most one row in the foreign table. If the
> foreign key field is not NULL, it must point to a valid row in the foreign
> table, but if it is NULL that means that it it not linked.
>
> Is there an automatic way to have the value of the foreign key field set to
> NULL if the linked row in the foreign table is deleted?
>
> Thanks,
> Mark
>
>
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