On 3 Feb 2014 09:51:20 Michael Bayer <mike...@zzzcomputing.com> wrote:
> On Feb 3, 2014, at 2:39 AM, Wolfgang Schnerring <w...@gocept.com> wrote:
> > I guess I didn't make it clear enough that I'm talking mainly about
> > this collections issue. Sorry about that; let me try again:
> > I feel it would be much more convenient if the state achieved by a savepoint
> > was reflected by collection properties (basically like a real commit), but I
> > don't know whether a) that fits sqlalchemy's usage concept and b) there are
> > adverse performance implications.
Sorry about the delay, but here's an example of the behaviour I'm talking about:
from sqlalchemy import Column, Integer, ForeignKey
from sqlalchemy.orm import relationship
import sqlalchemy.ext.declarative
import sqlalchemy.orm
import unittest
Base = sqlalchemy.ext.declarative.declarative_base()
class Parent(Base):
__tablename__ = 'parent'
id = Column(Integer, primary_key=True)
class Child(Base):
__tablename__ = 'child'
id = Column(Integer, primary_key=True)
parent_id = Column(Integer, ForeignKey('parent.id'))
parent = relationship(Parent, uselist=False, backref='children')
class ExpireTest(unittest.TestCase):
def setUp(self):
self.engine =
sqlalchemy.create_engine('postgresql://localhost/expiretest')
self.sessionmaker = sqlalchemy.orm.sessionmaker(bind=self.engine)
Base.metadata.create_all(self.engine)
def test_children_should_be_removed_from_collection_on_savepoint(self):
session = self.sessionmaker()
parent = Parent()
Child(parent=parent)
session.add(parent)
session.commit()
parent = session.query(Parent).first()
self.assertEqual(1, len(parent.children))
session.begin_nested()
session.delete(parent.children[0])
self.assertEqual(0, len(parent.children))
My point is, the last assertion fails, which I find both surprising and
inconvenient. ;) I'd be grateful for any insights you have about this.
Wolfgang
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