Hi,

I have a simple setup that may be summarized as:

  class User(Base):
       __tablename__ = 'user'
       name = Column(String(20), primary_key=True)

  class Mail(Base):
       __tablename__ = 'address'
       mail = Column(String(20), primary_key=True)
       user_name = Column(ForeignKey(User.name, ondelete="CASCADE"),
             nullable=False)


the generated DDL allows deletion of a user also in case it has
associated
addresses thanks to the ON DELETE CASCADE.

If I try to delete the object from sqlalchemy I get an error, since SA
tries
to set úser_name'attribute to NULL that is forbidden by the NOT NULL
constraint.


I can add a relation that will fix things by adding a backref:

  user = relation(User,
                 backref=backref('addresses', cascade='all, delete-
orphan'))

Is there a way to obtain that any cascading is left to the backend?
(pg in
my case). I have not been able to find references but I'm sure I saw
some
discussion on that already...


Thanks in advance

sandro
*:-)





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