06.06.2012 18:06, Michael Bayer kirjoitti:
you need to use the post_update option described at
http://docs.sqlalchemy.org/en/rel_0_7/orm/relationships.html#rows-that-point-to-themselves-mutually-dependent-rows
.
Thanks for the pointer. Problem solved :)
On Jun 6, 2012, at 1:15 AM, Alex Grönholm wrote:
I have trouble configuring two relationships from one class to
another. The following code should be fairly self-explanatory:
from sqlalchemy import *
from sqlalchemy.orm import *
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()
class Company(Base):
__tablename__ = 'companies'
id = Column(Integer, primary_key=True)
default_address_id = Column(Integer, ForeignKey('addresses.id',
use_alter=True, name='defaultaddress_fk'))
addresses = relationship('Address', backref='company',
primaryjoin='Address.company_id == Company.id')
default_address = relationship('Address',
primaryjoin='Company.default_address_id == Address.id')
class Address(Base):
__tablename__ = 'addresses'
id = Column(Integer, primary_key=True)
company_id = Column(Integer, ForeignKey(Company.id), nullable=False)
engine = create_engine('sqlite:///', echo=True)
Base.metadata.create_all(engine)
session = Session(engine)
company = Company()
address = Address()
session.add(company)
company.default_address = address
company.addresses.append(address)
session.flush()
What I expect is SQLAlchemy to 1) create the company, 2) create the
address with the new company's id in company_id, 3) assign the ID of
the new address to company.default_address_id
Trouble is, I get this error:
sqlalchemy.exc.CircularDependencyError: Circular dependency detected.
Cycles: set([ProcessState(ManyToOneDP(Company.default_address),
<Company at 0x16a7210>, delete=False),
ProcessState(ManyToOneDP(Address.company), <Address at 0x16ad190>,
delete=False), SaveUpdateState(<Company at 0x16a7210>),
ProcessState(OneToManyDP(Company.addresses), <Company at 0x16a7210>,
delete=False), SaveUpdateState(<Address at 0x16ad190>)]) all edges:
set([(ProcessState(OneToManyDP(Company.addresses), <Company at
0x16a7210>, delete=False), SaveUpdateState(<Address at 0x16ad190>)),
(SaveUpdateState(<Address at 0x16ad190>),
ProcessState(ManyToOneDP(Company.default_address), <Company at
0x16a7210>, delete=False)), (SaveUpdateState(<Company at 0x16a7210>),
SaveUpdateState(<Address at 0x16ad190>)), (SaveUpdateState(<Company
at 0x16a7210>), ProcessState(ManyToOneDP(Address.company), <Address
at 0x16ad190>, delete=False)),
(ProcessState(ManyToOneDP(Company.default_address), <Company at
0x16a7210>, delete=False), SaveUpdateState(<Company at 0x16a7210>)),
(ProcessState(ManyToOneDP(Address.company), <Address at 0x16ad190>,
delete=False), SaveUpdateState(<Address at 0x16ad190>)),
(SaveUpdateState(<Company at 0x16a7210>),
ProcessState(OneToManyDP(Company.addresses), <Company at 0x16a7210>,
delete=False))])
What am I doing wrong? I had a similar problem in my production app
when trying to delete a Company that had a default address assigned.
I'm on SQLAlchemy 0.7.7.
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