of course you'll get a cycle if you do this, though:
s1 = School(cod="S1", cod_riferimento="S1", cliente=False)
d1 = School(cod="D1", cod_riferimento="S1", cliente=False)
s1.sedi = [s1, d1]
s1->s1 is not supported by self referential flushes, unless you put
post_update=True on the relation() you have there.
On Aug 26, 2010, at 12:30 PM, Michael Bayer wrote:
> need a full test case. Here's yours, runs fine:
>
> from sqlalchemy.ext.declarative import declarative_base
> from sqlalchemy import *
> from sqlalchemy.types import *
> from sqlalchemy.orm import *
>
> Base = declarative_base()
> e = create_engine('sqlite://', echo=True)
> Base.metadata.bind = e
>
> sess = sessionmaker(e)()
>
> 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 = 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.commit()
>
>
> On Aug 26, 2010, at 12:12 PM, Alessandro Dentella wrote:
>
>> 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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