[Sqlalchemy-tickets] Issue #4193: versioning logic fails for mapping against a select stmt, 1.2 regression (zzzeek/sqlalchemy)

[Michael B. <iss...@bi...>]

New issue 4193: versioning logic fails for mapping against a select stmt, 1.2 regression
https://bitbucket.org/zzzeek/sqlalchemy/issues/4193/versioning-logic-fails-for-mapping-against

Michael Bayer:

```
#!python

class VersioningMappedSelectTest(fixtures.MappedTest):

    __backend__ = True

    @classmethod
    def define_tables(cls, metadata):
        Table('version_table', metadata,
              Column('id', Integer, primary_key=True,
                     test_needs_autoincrement=True),
              Column('version_id', Integer, nullable=False),
              Column('value', String(40), nullable=False))

    @classmethod
    def setup_classes(cls):
        class Foo(cls.Basic):
            pass

    def _fixture(self):
        Foo, version_table = self.classes.Foo, self.tables.version_table

        current = version_table.select().\
            where(version_table.c.id > 0).alias('current_table')

        mapper(Foo, current, version_id_col=version_table.c.version_id)
        s1 = Session()
        return s1

    @testing.emits_warning(r".*versioning cannot be verified")
    def test_multiple_updates(self):
        Foo = self.classes.Foo

        s1 = self._fixture()
        f1 = Foo(value='f1')
        f2 = Foo(value='f2')
        s1.add_all((f1, f2))
        s1.commit()

        f1.value = 'f1rev2'
        f2.value = 'f2rev2'
        s1.commit()

        eq_(
            s1.query(Foo.id, Foo.value, Foo.version_id).order_by(Foo.id).all(),
            [(f1.id, 'f1rev2', 2), (f2.id, 'f2rev2', 2)]
        )
```

result:


```
#!

Traceback (most recent call last):
  File "/home/classic/dev/sqlalchemy/test/orm/test_versioning.py", line 1682, in test_multiple_updates
    s1.commit()
  File "/home/classic/dev/sqlalchemy/test/../lib/sqlalchemy/orm/session.py", line 943, in commit
    self.transaction.commit()
  File "/home/classic/dev/sqlalchemy/test/../lib/sqlalchemy/orm/session.py", line 467, in commit
    self._prepare_impl()
  File "/home/classic/dev/sqlalchemy/test/../lib/sqlalchemy/orm/session.py", line 447, in _prepare_impl
    self.session.flush()
  File "/home/classic/dev/sqlalchemy/test/../lib/sqlalchemy/orm/session.py", line 2243, in flush
    self._flush(objects)
  File "/home/classic/dev/sqlalchemy/test/../lib/sqlalchemy/orm/session.py", line 2369, in _flush
    transaction.rollback(_capture_exception=True)
  File "/home/classic/dev/sqlalchemy/test/../lib/sqlalchemy/util/langhelpers.py", line 66, in __exit__
    compat.reraise(exc_type, exc_value, exc_tb)
  File "/home/classic/dev/sqlalchemy/test/../lib/sqlalchemy/util/compat.py", line 187, in reraise
    raise value
  File "/home/classic/dev/sqlalchemy/test/../lib/sqlalchemy/orm/session.py", line 2333, in _flush
    flush_context.execute()
  File "/home/classic/dev/sqlalchemy/test/../lib/sqlalchemy/orm/unitofwork.py", line 391, in execute
    rec.execute(self)
  File "/home/classic/dev/sqlalchemy/test/../lib/sqlalchemy/orm/unitofwork.py", line 556, in execute
    uow
  File "/home/classic/dev/sqlalchemy/test/../lib/sqlalchemy/orm/persistence.py", line 193, in save_obj
    update_version_id in states_to_update
  File "/home/classic/dev/sqlalchemy/test/../lib/sqlalchemy/orm/persistence.py", line 1132, in _finalize_insert_update_commands
    if state_dict[mapper._version_id_prop.key] is None:
KeyError: 'version_id'

```