Hi again, sorry for flooding with email this week...
I stumbled on the CircularDependencyError in some occasions with self
referencing models. I do understand that it can be tricky to INSERT and DELETE
but I'm just updating rows.
I reduced my problem to the bare minimum. It works both on 0.5.8 and 0.6.3
in the test case, but as long as I use the same objects from a graphical GUI
I get an error, Debugging with pdb, the problem arises on session.begin()
and in that moment the situation seems to me exactly the one of the test (2
objects, one modified).
I hope the error message is meaningful to you...
So the situation:
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Table, Column, ForeignKey
from sqlalchemy.types import *
from sqlalchemy import orm, sql
Base = declarative_base()
URL = 'postgresql://localhost/scuole'
Base.metadata.bind = URL
Session = orm.sessionmaker()
sess = Session(bind=Base.metadata.bind, expire_on_commit=False,
autoflush=False, autocommit=True, )
class School(Base):
__tablename__ = 'scuola_scuola'
cod = Column(String(10), primary_key=True)
denominazione= Column(String(120))
cod_riferimento = Column(String(10), ForeignKey(cod))
cliente = Column(Boolean, nullable=False)
sedi = orm.relation('School', )
def __repr__(self):
return self.cod
Base.metadata.create_all()
# s1 = School(cod="S1", cod_riferimento="S1", cliente=False)
# d1 = School(cod="D1", cod_riferimento="S1", cliente=False)
# sess.add(s1)
# sess.add(d1)
# sess.commit()
s1 = sess.query(School).get('S1')
d1 = sess.query(School).get('D1')
d1.cliente = False
sess.begin()
sess.commit()
This same peace of code (i.e.: same session with just s1, d1), run from
within a GUI raises an error (only with SA 0.6.3, 0.5.8 just works). The
error is:
Traceback (most recent call last):
File "/misc/src/hg/py/sqlkit/sqlkit/widgets/mask/mask.py", line 388, in
record_save_cb
self.record_save(None)
File "/misc/src/hg/py/sqlkit/sqlkit/widgets/mask/mask.py", line 422, in
record_save
self.commit()
File "/misc/src/hg/py/sqlkit/sqlkit/widgets/common/sqlwidget.py", line 972,
in commit
self.session.begin()
File "/misc/src/sqlalchemy/sqlalchemy/lib/sqlalchemy/orm/session.py", line
598, in begin
self, nested=nested)
File "/misc/src/sqlalchemy/sqlalchemy/lib/sqlalchemy/orm/session.py", line
223, in __init__
self._take_snapshot()
File "/misc/src/sqlalchemy/sqlalchemy/lib/sqlalchemy/orm/session.py", line
271, in _take_snapshot
self.session.flush()
File "/misc/src/sqlalchemy/sqlalchemy/lib/sqlalchemy/orm/session.py", line
1346, in flush
self._flush(objects)
File "/misc/src/sqlalchemy/sqlalchemy/lib/sqlalchemy/orm/session.py", line
1427, in _flush
flush_context.execute()
File "/misc/src/sqlalchemy/sqlalchemy/lib/sqlalchemy/orm/unitofwork.py", line
291, in execute
postsort_actions):
File "/misc/src/sqlalchemy/sqlalchemy/lib/sqlalchemy/topological.py", line
31, in sort_as_subsets
(find_cycles(tuples, allitems), _dump_edges(edges, True)))
sqlalchemy.exc.CircularDependencyError: Circular dependency detected:
cycles: set([SaveUpdateState(<School at 0x8da616c>),
ProcessState(OneToManyDP(School.sedi), <School at 0x8da616c>,
delete=False)]) all edges: [(SaveUpdateState(<School at 0x8da616c>),
ProcessState(OneToManyDP(School.sedi), <School at 0x8da616c>,
delete=False)), (ProcessState(OneToManyDP(School.sedi), <School at
0x8da616c>, delete=False), SaveUpdateState(<School at 0x8da616c>)),
(SaveUpdateState(<School at 0x8da616c>), SaveUpdateState(<School at
0x8da616c>)), (SaveUpdateState(<School at 0x8da616c>),
SaveUpdateState(<School at 0x8da61ec>)),
(ProcessState(OneToManyDP(School.sedi), <School at 0x8da616c>,
delete=False), SaveUpdateState(<School at 0x8da61ec>))]
How can I further investigate what Is wrong from the setup of my GUI?
Thanks again
sandro
*:-)
--
Sandro Dentella *:-)
http://sqlkit.argolinux.org SQLkit home page - PyGTK/python/sqlalchemy
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