I just came across this issue where if an IntegrityError is raised on
session.commit() then the offending object that caused the error is
automatically removed from the session. If the object is a "child"
object is related to "parent" object and the child object is in
session.new then it is removed from the parent's collection. If it's
not in the session.new then it is removed from the session but not the
parent's collection.
Is this the intended result? If so, why?
I think this is best explained with code:
--------+ cut +----------
from sqlalchemy import *
from sqlalchemy.orm import *
from sqlalchemy.ext.declarative import declarative_base
uri = 'sqlite:///:memory:'
Base = declarative_base()
class User(Base):
__tablename__ = 'user'
name = Column(String, primary_key=True)
address = relation('Address', uselist=False, cascade='all, delete-
orphan')
phones = relation('Phone', cascade='all, delete-orphan',
backref=backref('accession', uselist=False))
class Address(Base):
__tablename__ = 'address'
address = Column(String, primary_key=True)
user_key = Column(String, ForeignKey('user.name'))
class Phone(Base):
__tablename__ = 'phone'
number = Column(String, primary_key=True)
user_key = Column(String, ForeignKey('user.name'))
engine = create_engine(uri)
Base.metadata.bind = engine
Base.metadata.create_all()
session = sessionmaker()()
def test1():
"""Create the users and address and commit() the changes and then
later add the phone number...in this case the phone number will be
removed from user.phones and the session
"""
user = User(name='Bob')
address = Address(address='Somewhere')
user.address = address
session.add_all([user, address])
session.commit()
phone = Phone()
user.phones.append(phone)
session.add(phone)
try:
session.commit()
except Exception, e:
session.rollback()
print e
assert phone in user.phones # fails
assert phone in session # fails
def test2():
"""Create the users and address and commit() the changes and then
later add the phone number...in this case the phone number will
still be in user.phones but removed from the session
"""
user = User(name='Bob')
address = Address(address='Somewhere')
phone = Phone()
user.phones.append(phone)
user.address = address
session.add_all([user, address, phone])
objs = list(session)
try:
session.commit()
except Exception, e:
session.rollback()
print e
# if we re-add all the objects that were in the session before the
# commit and fix the problem then then everything works fine...
# is there a downside to this?
#session.add_all(objs)
#phone.number=1
#session.commit()
assert user.address == address # passes
assert phone in user.phones # passes
assert phone in session # fails
#test1()
test2()
-------------------------
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