[sqlalchemy] Cascading orphan deletes in self-referential table
Hi,
I'm using the following table (shortened, removed unnecessary columns)
to store a menu tree.
class MenuNode(Base):
__tablename__ = 'menu'
id = Column(Integer, primary_key=True, nullable=False,
unique=True)
parent_id = Column(Integer, ForeignKey('menu.id',
onupdate='CASCADE', ondelete='CASCADE'), nullable=True, index=True)
name = Column(String(64), nullable=False)
parent = relationship('MenuNode', remote_side='MenuNode.id',
cascade='all, delete', passive_deletes=True,
backref=backref('children', order_by=position))
Top-level menu nodes have parent_id=NULL.
When deleting a node via session.delete(node) sqlalchemy issues UPDATE
statements to set all children's parent_id fields to NULL instead of
deleting the children.
How can i tell SA that I want to delete any children?
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Re: [sqlalchemy] Cascading orphan deletes in self-referential table
On 4/25/2010 6:39 AM, Adrian wrote:
class MenuNode(Base):
__tablename__ = 'menu'
id = Column(Integer, primary_key=True, nullable=False,
unique=True)
parent_id = Column(Integer, ForeignKey('menu.id',
onupdate='CASCADE', ondelete='CASCADE'), nullable=True, index=True)
name = Column(String(64), nullable=False)
parent = relationship('MenuNode', remote_side='MenuNode.id',
cascade='all, delete', passive_deletes=True,
backref=backref('children', order_by=position))
Top-level menu nodes have parent_id=NULL.
When deleting a node via session.delete(node) sqlalchemy issues UPDATE
statements to set all children's parent_id fields to NULL instead of
deleting the children.
How can i tell SA that I want to delete any children?
Does specifying cascade='all, delete-orphan' on the parent relationship
accomplish what you're after?
Lance
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Re: [sqlalchemy] Cascading orphan deletes in self-referential table
Does specifying cascade='all, delete-orphan' on the parent relationship accomplish what you're after? delete-orphan doesn't work in self-relational relationships (there are always some nodes without a parent). However, moving passive_deletes=True into the backref() fixed it. -- Adrian -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
