Hi All,
With these models:
class User(Base):
__tablename__ = 'user'
__table_args__ = {'mysql_engine':'InnoDB'}
username = Column(String(50), primary_key=True)
grants = dynamic_loader("Grant")
class Grant(Base):
__tablename__ = 'grant'
__table_args__ = {'mysql_engine':'InnoDB'}
username = Column(String(50),
ForeignKey('user.username',ondelete='cascade'),
primary_key=True)
user = relation("User",cascade="all")
And an autoflush=True, autocommit=False, Session backed onto a MySQL
database, if I do:
user = User(username='testname',
password='testpassword')
session.add(user)
session.add(Grant(user=user)))
assert session.query(User).count()
...then no SQL is executed until the query, and at that point, the order
of execution of the two insert statements appears random, such that
sometimes the grant is inserted first, resulting in an IntegrityError as
the foreign key constraint fails.
What am I doing wrong here and why is the order of the SQL emitted
apparently arbitrary?
Now, if it does succeed, and I go on to do:
session.delete(session.query(User).get('testname'))
assert session.query(User).count()==0
When the count is executed, I get:
assert session.query(User).count()==0
File
"/home/chris/buildout-eggs/SQLAlchemy-0.6.6-py2.6.egg/sqlalchemy/orm/query.py",
line 2010, in count
should_nest = should_nest[0]
File
"/home/chris/buildout-eggs/SQLAlchemy-0.6.6-py2.6.egg/sqlalchemy/orm/query.py",
line 2045, in _col_aggregate
self.session._autoflush()
File
"/home/chris/buildout-eggs/SQLAlchemy-0.6.6-py2.6.egg/sqlalchemy/orm/session.py",
line 862, in _autoflush
self.flush()
File
"/home/chris/buildout-eggs/SQLAlchemy-0.6.6-py2.6.egg/sqlalchemy/orm/session.py",
line 1388, in flush
self._flush(objects)
File
"/home/chris/buildout-eggs/SQLAlchemy-0.6.6-py2.6.egg/sqlalchemy/orm/session.py",
line 1469, in _flush
flush_context.execute()
File
"/home/chris/buildout-eggs/SQLAlchemy-0.6.6-py2.6.egg/sqlalchemy/orm/unitofwork.py",
line 302, in execute
rec.execute(self)
File
"/home/chris/buildout-eggs/SQLAlchemy-0.6.6-py2.6.egg/sqlalchemy/orm/unitofwork.py",
line 402, in execute
self.dependency_processor.process_deletes(uow, states)
File
"/home/chris/buildout-eggs/SQLAlchemy-0.6.6-py2.6.egg/sqlalchemy/orm/dependency.py",
line 488, in process_deletes
uowcommit, False)
File
"/home/chris/buildout-eggs/SQLAlchemy-0.6.6-py2.6.egg/sqlalchemy/orm/dependency.py",
line 532, in _synchronize
sync.clear(dest, self.mapper, self.prop.synchronize_pairs)
File
"/home/chris/buildout-eggs/SQLAlchemy-0.6.6-py2.6.egg/sqlalchemy/orm/sync.py",
line 41, in clear
(r, mapperutil.state_str(dest))
AssertionError: Dependency rule tried to blank-out primary key column
'grant.username' on instance '<Grant at 0x9ed946c>'
...which is confusing. Why doesn't the cascade on the Grant.user
relation stop this happening?
cheers,
Chris
--
Simplistix - Content Management, Batch Processing & Python Consulting
- http://www.simplistix.co.uk
--
You received this message because you are subscribed to the Google Groups
"sqlalchemy" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sqlalchemy?hl=en.
