28 files changed, 216 insertions, 217 deletions

diff --git a/src/mailman/app/subscriptions.py b/src/mailman/app/subscriptions.py
index 303303e70..99c6ab2de 100644
--- a/src/mailman/app/subscriptions.py
+++ b/src/mailman/app/subscriptions.py
@@ -88,8 +88,7 @@ class SubscriptionService:
     @dbconnection
     def get_member(self, store, member_id):
         """See `ISubscriptionService`."""
-        members = store.query(Member).filter(
-            Member._member_id == member_id)
+        members = store.query(Member).filter(Member._member_id == member_id)
         if members.count() == 0:
             return None
         else:
@@ -117,7 +116,7 @@ class SubscriptionService:
                 if address is None or user is None:
                     return []
                 query.append(or_(Member.address_id == address.id,
-                                Member.user_id == user.id))
+                                 Member.user_id == user.id))
             else:
                 # subscriber is a user id.
                 user = user_manager.get_user_by_id(subscriber)
@@ -126,7 +125,7 @@ class SubscriptionService:
                 if len(address_ids) == 0 or user is None:
                     return []
                 query.append(or_(Member.user_id == user.id,
-                                Member.address_id.in_(address_ids)))
+                                 Member.address_id.in_(address_ids)))
         # Calculate the rest of the query expression, which will get And'd
         # with the Or clause above (if there is one).
         if list_id is not None:
diff --git a/src/mailman/database/base.py b/src/mailman/database/base.py
index f379b3124..8c426f8cf 100644
--- a/src/mailman/database/base.py
+++ b/src/mailman/database/base.py
@@ -19,28 +19,22 @@ from __future__ import absolute_import, print_function, unicode_literals
 
 __metaclass__ = type
 __all__ = [
-    'StormBaseDatabase',
+    'SABaseDatabase',
     ]
 
 
-import os
-import sys
 import logging
 
-from lazr.config import as_boolean
-from pkg_resources import resource_listdir, resource_string
 from sqlalchemy import create_engine
 from sqlalchemy.orm import sessionmaker
-from sqlalchemy.orm.session import Session
 from zope.interface import implementer
 
 from mailman.config import config
 from mailman.interfaces.database import IDatabase
-from mailman.model.version import Version
 from mailman.utilities.string import expand
 
-log = logging.getLogger('mailman.config')
 
+log = logging.getLogger('mailman.config')
 NL = '\n'
 
 
@@ -53,17 +47,15 @@ class SABaseDatabase:
     """
     # Tag used to distinguish the database being used.  Override this in base
     # classes.
-
     TAG = ''
 
     def __init__(self):
         self.url = None
         self.store = None
-        self.transaction = None
 
     def begin(self):
         """See `IDatabase`."""
-        # SA does this for us.
+        # SQLAlchemy does this for us.
         pass
 
     def commit(self):
@@ -102,9 +94,13 @@ class SABaseDatabase:
         """
         pass
 
+    # XXX Abhilash removed teh _prepare() method.  Is that because SA takes
+    # care of this for us?  If so, then the comment below must be updated.
+    # For reference, the SQLite bug is marked "won't fix".
+
     def initialize(self, debug=None):
-        """See `IDatabase`"""
-        # Calculate the engine url
+        """See `IDatabase`."""
+        # Calculate the engine url.
         url = expand(config.database.url, config.paths)
         log.debug('Database url: %s', url)
         # XXX By design of SQLite, database file creation does not honor
@@ -127,6 +123,9 @@ class SABaseDatabase:
         self.store = session()
         self.store.commit()
 
+    # XXX We should probably rename load_migrations() and perhaps get rid of
+    # load_sql().  The latter is never called any more.
+
     def load_migrations(self, until=None):
         """Load schema migrations.
 
diff --git a/src/mailman/database/factory.py b/src/mailman/database/factory.py
index 64fcc242c..450672e5b 100644
--- a/src/mailman/database/factory.py
+++ b/src/mailman/database/factory.py
@@ -62,6 +62,7 @@ class DatabaseFactory:
 
 def _reset(self):
     """See `IDatabase`."""
+    # Avoid a circular import at module level.
     from mailman.database.model import Model
     self.store.rollback()
     self._pre_reset(self.store)
diff --git a/src/mailman/database/model.py b/src/mailman/database/model.py
index d86ebb80e..f8a15162c 100644
--- a/src/mailman/database/model.py
+++ b/src/mailman/database/model.py
@@ -26,23 +26,31 @@ __all__ = [
 
 
 import contextlib
-from operator import attrgetter
 
 from sqlalchemy.ext.declarative import declarative_base
 
 from mailman.config import config
 
-class ModelMeta(object):
-    """Do more magic on table classes."""
 
+class ModelMeta:
+    """The custom metaclass for all model base classes.
+
+    This is used in the test suite to quickly reset the database after each
+    test.  It works by iterating over all the tables, deleting each.  The test
+    suite will then recreate the tables before each test.
+    """
     @staticmethod
     def _reset(db):
-        meta = Model.metadata
-        engine = config.db.engine
-        with contextlib.closing(engine.connect()) as con:
-            trans = con.begin()
-            for table in reversed(meta.sorted_tables):
-                con.execute(table.delete())
-            trans.commit()
+        with contextlib.closing(config.db.engine.connect()) as connection:
+            transaction = connection.begin()
+            try:
+                for table in reversed(Model.metadata.sorted_tables):
+                    connection.execute(table.delete())
+            except:
+                transaction.abort()
+                raise
+            else:
+                transaction.commit()
+
 
 Model = declarative_base(cls=ModelMeta)
diff --git a/src/mailman/database/sqlite.py b/src/mailman/database/sqlite.py
index 0594d9091..b70e474cc 100644
--- a/src/mailman/database/sqlite.py
+++ b/src/mailman/database/sqlite.py
@@ -56,7 +56,7 @@ class SQLiteDatabase(SABaseDatabase):
         assert parts.scheme == 'sqlite', (
             'Database url mismatch (expected sqlite prefix): {0}'.format(url))
         path = os.path.normpath(parts.path)
-        fd = os.open(path, os.O_WRONLY |  os.O_NONBLOCK | os.O_CREAT, 0666)
+        fd = os.open(path, os.O_WRONLY |  os.O_NONBLOCK | os.O_CREAT, 0o666)
         # Ignore errors
         if fd > 0:
             os.close(fd)
@@ -72,7 +72,7 @@ def _cleanup(self, tempdir):
 def make_temporary(database):
     """Adapts by monkey patching an existing SQLite IDatabase."""
     tempdir = tempfile.mkdtemp()
-    url = 'sqlite:///'   + os.path.join(tempdir, 'mailman.db')
+    url = 'sqlite:///' + os.path.join(tempdir, 'mailman.db')
     with configuration('database', url=url):
         database.initialize()
     database._cleanup = types.MethodType(
diff --git a/src/mailman/database/types.py b/src/mailman/database/types.py
index a6f0b32ca..380ce37dc 100644
--- a/src/mailman/database/types.py
+++ b/src/mailman/database/types.py
@@ -29,30 +29,28 @@ __all__ = [
 import uuid
 
 from sqlalchemy import Integer
-from sqlalchemy.types import TypeDecorator, BINARY, CHAR
 from sqlalchemy.dialects import postgresql
+from sqlalchemy.types import TypeDecorator, BINARY, CHAR
 
 
 
 class Enum(TypeDecorator):
-    """
-    Stores an integer-based Enum as an integer in the database, and converts it
-    on-the-fly.
-    """
+    """Handle Python 3.4 style enums.
 
+    Stores an integer-based Enum as an integer in the database, and
+    converts it on-the-fly.
+    """
     impl = Integer
 
-    def __init__(self, *args, **kw):
-        self.enum = kw.pop("enum")
-        TypeDecorator.__init__(self, *args, **kw)
+    def __init__(self, enum, *args, **kw):
+        self.enum = enum
+        super(Enum, self).__init__(*args, **kw)
 
     def process_bind_param(self, value, dialect):
         if value is None:
             return None
-
         return value.value
 
-
     def process_result_value(self, value, dialect):
         if value is None:
             return None
@@ -61,29 +59,12 @@ class Enum(TypeDecorator):
 
 
 class UUID(TypeDecorator):
-    """
-    Stores a UUID in the database natively when it can and falls back to
-    a BINARY(16) or a CHAR(32) when it can't.
-
-    ::
-
-        from sqlalchemy_utils import UUIDType
-        import uuid
-
-        class User(Base):
-            __tablename__ = 'user'
+    """Handle UUIds."""
 
-            # Pass `binary=False` to fallback to CHAR instead of BINARY
-            id = sa.Column(UUIDType(binary=False), primary_key=True)
-    """
     impl = BINARY(16)
-
     python_type = uuid.UUID
 
     def __init__(self, binary=True, native=True):
-        """
-        :param binary: Whether to use a BINARY(16) or CHAR(32) fallback.
-        """
         self.binary = binary
         self.native = native
 
@@ -91,7 +72,6 @@ class UUID(TypeDecorator):
         if dialect.name == 'postgresql' and self.native:
             # Use the native UUID type.
             return dialect.type_descriptor(postgresql.UUID())
-
         else:
             # Fallback to either a BINARY or a CHAR.
             kind = self.impl if self.binary else CHAR(32)
@@ -102,29 +82,22 @@ class UUID(TypeDecorator):
         if value and not isinstance(value, uuid.UUID):
             try:
                 value = uuid.UUID(value)
-
             except (TypeError, ValueError):
                 value = uuid.UUID(bytes=value)
-
         return value
 
     def process_bind_param(self, value, dialect):
         if value is None:
             return value
-
         if not isinstance(value, uuid.UUID):
             value = self._coerce(value)
-
         if self.native and dialect.name == 'postgresql':
             return str(value)
-
         return value.bytes if self.binary else value.hex
 
     def process_result_value(self, value, dialect):
         if value is None:
             return value
-
         if self.native and dialect.name == 'postgresql':
             return uuid.UUID(value)
-
         return uuid.UUID(bytes=value) if self.binary else uuid.UUID(value)
diff --git a/src/mailman/interfaces/database.py b/src/mailman/interfaces/database.py
index d8fde2b93..c2997ba6b 100644
--- a/src/mailman/interfaces/database.py
+++ b/src/mailman/interfaces/database.py
@@ -61,7 +61,7 @@ class IDatabase(Interface):
         """Abort the current transaction."""
 
     store = Attribute(
-        """The underlying SQLAlchemy store on which you can do queries.""")
+        """The underlying database object on which you can do queries.""")
 
 
 
diff --git a/src/mailman/model/address.py b/src/mailman/model/address.py
index 7203a31a5..d078f28d5 100644
--- a/src/mailman/model/address.py
+++ b/src/mailman/model/address.py
@@ -26,8 +26,8 @@ __all__ = [
 
 
 from email.utils import formataddr
-from sqlalchemy import (Column, Integer, String, Unicode,
-                        ForeignKey, DateTime)
+from sqlalchemy import (
+    Column, DateTime, ForeignKey, Integer, Unicode)
 from sqlalchemy.orm import relationship, backref
 from zope.component import getUtility
 from zope.event import notify
@@ -56,10 +56,11 @@ class Address(Model):
     user_id = Column(Integer, ForeignKey('user.id'))
 
     preferences_id = Column(Integer, ForeignKey('preferences.id'))
-    preferences = relationship('Preferences',
-                              backref=backref('Address', uselist=False))
+    preferences = relationship(
+        'Preferences', backref=backref('Address', uselist=False))
 
     def __init__(self, email, display_name):
+        super(Address, self).__init__()
         getUtility(IEmailValidator).validate(email)
         lower_case = email.lower()
         self.email = lower_case
diff --git a/src/mailman/model/autorespond.py b/src/mailman/model/autorespond.py
index c3aff174a..c74434f7b 100644
--- a/src/mailman/model/autorespond.py
+++ b/src/mailman/model/autorespond.py
@@ -26,8 +26,7 @@ __all__ = [
     ]
 
 
-from sqlalchemy import (Column, Integer, String, Unicode,
-                        ForeignKey, Date)
+from sqlalchemy import Column, Date, ForeignKey, Integer
 from sqlalchemy import desc
 from sqlalchemy.orm import relationship
 from zope.interface import implementer
@@ -55,7 +54,7 @@ class AutoResponseRecord(Model):
     mailing_list_id = Column(Integer, ForeignKey('mailinglist.id'))
     mailing_list = relationship('MailingList')
 
-    response_type = Column(Enum(enum=Response))
+    response_type = Column(Enum(Response))
     date_sent = Column(Date)
 
     def __init__(self, mailing_list, address, response_type):
@@ -77,10 +76,10 @@ class AutoResponseSet:
     def todays_count(self, store, address, response_type):
         """See `IAutoResponseSet`."""
         return store.query(AutoResponseRecord).filter_by(
-            address = address,
-            mailing_list = self._mailing_list,
-            response_type = response_type,
-            date_sent = today()).count()
+            address=address,
+            mailing_list=self._mailing_list,
+            response_type=response_type,
+            date_sent=today()).count()
 
     @dbconnection
     def response_sent(self, store, address, response_type):
@@ -93,8 +92,8 @@ class AutoResponseSet:
     def last_response(self, store, address, response_type):
         """See `IAutoResponseSet`."""
         results = store.query(AutoResponseRecord).filter_by(
-            address = address,
-            mailing_list = self._mailing_list,
-            response_type = response_type
+            address=address,
+            mailing_list=self._mailing_list,
+            response_type=response_type
             ).order_by(desc(AutoResponseRecord.date_sent))
         return (None if results.count() == 0 else results.first())
diff --git a/src/mailman/model/bans.py b/src/mailman/model/bans.py
index fbbecaebd..8678fc1e7 100644
--- a/src/mailman/model/bans.py
+++ b/src/mailman/model/bans.py
@@ -72,8 +72,8 @@ class BanManager:
     @dbconnection
     def unban(self, store, email):
         """See `IBanManager`."""
-        ban = store.query(Ban).filter_by(email=email,
-                                         list_id=self._list_id).first()
+        ban = store.query(Ban).filter_by(
+            email=email, list_id=self._list_id).first()
         if ban is not None:
             store.delete(ban)
 
diff --git a/src/mailman/model/bounce.py b/src/mailman/model/bounce.py
index 1165fee96..cd658052d 100644
--- a/src/mailman/model/bounce.py
+++ b/src/mailman/model/bounce.py
@@ -27,7 +27,7 @@ __all__ = [
 
 
 
-from sqlalchemy import Column, Integer, Unicode, DateTime, Boolean
+from sqlalchemy import Boolean, Column, DateTime, Integer, Unicode
 from zope.interface import implementer
 
 from mailman.database.model import Model
@@ -50,7 +50,7 @@ class BounceEvent(Model):
     email = Column(Unicode)
     timestamp = Column(DateTime)
     message_id = Column(Unicode)
-    context = Column(Enum(enum=BounceContext))
+    context = Column(Enum(BounceContext))
     processed = Column(Boolean)
 
     def __init__(self, list_id, email, msg, context=None):
@@ -85,5 +85,5 @@ class BounceProcessor:
     @dbconnection
     def unprocessed(self, store):
         """See `IBounceProcessor`."""
-        for event in store.query(BounceEvent).filter_by(processed = False):
+        for event in store.query(BounceEvent).filter_by(processed=False):
             yield event
diff --git a/src/mailman/model/digests.py b/src/mailman/model/digests.py
index 1b7140824..7bfd512b6 100644
--- a/src/mailman/model/digests.py
+++ b/src/mailman/model/digests.py
@@ -50,7 +50,7 @@ class OneLastDigest(Model):
     address_id = Column(Integer, ForeignKey('address.id'))
     address = relationship('Address')
 
-    delivery_mode = Column(Enum(enum=DeliveryMode))
+    delivery_mode = Column(Enum(DeliveryMode))
 
     def __init__(self, mailing_list, address, delivery_mode):
         self.mailing_list = mailing_list
diff --git a/src/mailman/model/domain.py b/src/mailman/model/domain.py
index 585eccf3d..083e1cf51 100644
--- a/src/mailman/model/domain.py
+++ b/src/mailman/model/domain.py
@@ -26,8 +26,8 @@ __all__ = [
     ]
 
 
+from sqlalchemy import Column, Integer, Unicode
 from urlparse import urljoin, urlparse
-from sqlalchemy import Column, Unicode, Integer
 from zope.event import notify
 from zope.interface import implementer
 
diff --git a/src/mailman/model/language.py b/src/mailman/model/language.py
index 7b611b6d8..15450c936 100644
--- a/src/mailman/model/language.py
+++ b/src/mailman/model/language.py
@@ -25,8 +25,8 @@ __all__ = [
     ]
 
 
+from sqlalchemy import Column, Integer, Unicode
 from zope.interface import implementer
-from sqlalchemy import Column, Unicode, Integer
 
 from mailman.database import Model
 from mailman.interfaces import ILanguage
diff --git a/src/mailman/model/mailinglist.py b/src/mailman/model/mailinglist.py
index 385262f28..d00cf3d31 100644
--- a/src/mailman/model/mailinglist.py
+++ b/src/mailman/model/mailinglist.py
@@ -27,10 +27,11 @@ __all__ = [
 
 import os
 
-from sqlalchemy import (Column, Boolean, DateTime, Float, Integer, Unicode,
-                        PickleType, Interval, ForeignKey, LargeBinary)
-from sqlalchemy import event
-from sqlalchemy.orm import relationship, sessionmaker
+from sqlalchemy import (
+    Boolean, Column, DateTime, Float, ForeignKey, Integer, Interval,
+    LargeBinary, PickleType, Unicode)
+from sqlalchemy.event import listen
+from sqlalchemy.orm import relationship
 from urlparse import urljoin
 from zope.component import getUtility
 from zope.event import notify
@@ -38,6 +39,7 @@ from zope.interface import implementer
 
 from mailman.config import config
 from mailman.database.model import Model
+from mailman.database.transaction import dbconnection
 from mailman.database.types import Enum
 from mailman.interfaces.action import Action, FilterAction
 from mailman.interfaces.address import IAddress
@@ -68,7 +70,6 @@ from mailman.utilities.string import expand
 SPACE = ' '
 UNDERSCORE = '_'
 
-Session = sessionmaker()
 
 
 @implementer(IMailingList)
@@ -100,9 +101,6 @@ class MailingList(Model):
     digest_last_sent_at = Column(DateTime)
     volume = Column(Integer)
     last_post_at = Column(DateTime)
-    # Implicit destination.
-    # acceptable_aliases_id = Column(Integer, ForeignKey('acceptablealias.id'))
-    # acceptable_alias = relationship('AcceptableAlias', backref='mailing_list')
     # Attributes which are directly modifiable via the web u/i.  The more
     # complicated attributes are currently stored as pickles, though that
     # will change as the schema and implementation is developed.
@@ -110,17 +108,17 @@ class MailingList(Model):
     admin_immed_notify = Column(Boolean)
     admin_notify_mchanges = Column(Boolean)
     administrivia = Column(Boolean)
-    archive_policy = Column(Enum(enum=ArchivePolicy))
+    archive_policy = Column(Enum(ArchivePolicy))
     # Automatic responses.
     autoresponse_grace_period = Column(Interval)
-    autorespond_owner = Column(Enum(enum=ResponseAction))
+    autorespond_owner = Column(Enum(ResponseAction))
     autoresponse_owner_text = Column(Unicode)
-    autorespond_postings = Column(Enum(enum=ResponseAction))
+    autorespond_postings = Column(Enum(ResponseAction))
     autoresponse_postings_text = Column(Unicode)
-    autorespond_requests = Column(Enum(enum=ResponseAction))
+    autorespond_requests = Column(Enum(ResponseAction))
     autoresponse_request_text = Column(Unicode)
     # Content filters.
-    filter_action = Column(Enum(enum=FilterAction))
+    filter_action = Column(Enum(FilterAction))
     filter_content = Column(Boolean)
     collapse_alternatives = Column(Boolean)
     convert_html_to_plaintext = Column(Boolean)
@@ -132,18 +130,19 @@ class MailingList(Model):
     bounce_score_threshold = Column(Integer) # XXX
     bounce_you_are_disabled_warnings = Column(Integer) # XXX
     bounce_you_are_disabled_warnings_interval = Column(Interval) # XXX
-    forward_unrecognized_bounces_to = Column(Enum(enum=UnrecognizedBounceDisposition))
+    forward_unrecognized_bounces_to = Column(
+        Enum(UnrecognizedBounceDisposition))
     process_bounces = Column(Boolean)
     # Miscellaneous
-    default_member_action = Column(Enum(enum=Action))
-    default_nonmember_action = Column(Enum(enum=Action))
+    default_member_action = Column(Enum(Action))
+    default_nonmember_action = Column(Enum(Action))
     description = Column(Unicode)
     digest_footer_uri = Column(Unicode)
     digest_header_uri = Column(Unicode)
     digest_is_default = Column(Boolean)
     digest_send_periodic = Column(Boolean)
     digest_size_threshold = Column(Float)
-    digest_volume_frequency = Column(Enum(enum=DigestFrequency))
+    digest_volume_frequency = Column(Enum(DigestFrequency))
     digestable = Column(Boolean)
     discard_these_nonmembers = Column(PickleType)
     emergency = Column(Boolean)
@@ -166,21 +165,21 @@ class MailingList(Model):
     mime_is_default_digest = Column(Boolean)
     # FIXME: There should be no moderator_password
     moderator_password = Column(LargeBinary) # TODO : was RawStr()
-    newsgroup_moderation = Column(Enum(enum=NewsgroupModeration))
+    newsgroup_moderation = Column(Enum(NewsgroupModeration))
     nntp_prefix_subject_too = Column(Boolean)
     nondigestable = Column(Boolean)
     nonmember_rejection_notice = Column(Unicode)
     obscure_addresses = Column(Boolean)
     owner_chain = Column(Unicode)
     owner_pipeline = Column(Unicode)
-    personalize = Column(Enum(enum=Personalization))
+    personalize = Column(Enum(Personalization))
     post_id = Column(Integer)
     posting_chain = Column(Unicode)
     posting_pipeline = Column(Unicode)
     _preferred_language = Column('preferred_language', Unicode)
     display_name = Column(Unicode)
     reject_these_nonmembers = Column(PickleType)
-    reply_goes_to_list = Column(Enum(enum=ReplyToMunging))
+    reply_goes_to_list = Column(Enum(ReplyToMunging))
     reply_to_address = Column(Unicode)
     require_explicit_destination = Column(Boolean)
     respond_to_post_requests = Column(Boolean)
@@ -194,6 +193,7 @@ class MailingList(Model):
     welcome_message_uri = Column(Unicode)
 
     def __init__(self, fqdn_listname):
+        super(MailingList, self).__init__()
         listname, at, hostname = fqdn_listname.partition('@')
         assert hostname, 'Bad list name: {0}'.format(fqdn_listname)
         self.list_name = listname
@@ -201,15 +201,15 @@ class MailingList(Model):
         self._list_id = '{0}.{1}'.format(listname, hostname)
         # For the pending database
         self.next_request_id = 1
-        # We need to set up the rosters.  Normally, this method will get
-        # called when the MailingList object is loaded from the database, but
-        # that's not the case when the constructor is called.  So, set up the
-        # rosters explicitly.
+        # We need to set up the rosters.  Normally, this method will get called
+        # when the MailingList object is loaded from the database, but when the
+        # constructor is called, SQLAlchemy's `load` event isn't triggered.
+        # Thus we need to set up the rosters explicitly.
         self._post_load()
         makedirs(self.data_path)
 
-
     def _post_load(self, *args):
+        # This hooks up to SQLAlchemy's `load` event.
         self.owners = roster.OwnerRoster(self)
         self.moderators = roster.ModeratorRoster(self)
         self.administrators = roster.AdministratorRoster(self)
@@ -221,7 +221,10 @@ class MailingList(Model):
 
     @classmethod
     def __declare_last__(cls):
-        event.listen(cls, 'load', cls._post_load)
+        # SQLAlchemy special directive hook called after mappings are assumed
+        # to be complete.  Use this to connect the roster instance creation
+        # method with the SA `load` event.
+        listen(cls, 'load', cls._post_load)
 
     def __repr__(self):
         return '<mailing list "{0}" at {1:#x}>'.format(
@@ -331,15 +334,17 @@ class MailingList(Model):
         except AttributeError:
             self._preferred_language = language
 
-    def send_one_last_digest_to(self, address, delivery_mode):
+    @dbconnection
+    def send_one_last_digest_to(self, store, address, delivery_mode):
         """See `IMailingList`."""
         digest = OneLastDigest(self, address, delivery_mode)
-        Session.object_session(self).add(digest)
+        store.add(digest)
 
     @property
-    def last_digest_recipients(self):
+    @dbconnection
+    def last_digest_recipients(self, store):
         """See `IMailingList`."""
-        results = Session.object_session(self).query(OneLastDigest).filter(
+        results = store.query(OneLastDigest).filter(
             OneLastDigest.mailing_list == self)
         recipients = [(digest.address, digest.delivery_mode)
                       for digest in results]
@@ -347,19 +352,20 @@ class MailingList(Model):
         return recipients
 
     @property
-    def filter_types(self):
+    @dbconnection
+    def filter_types(self, store):
         """See `IMailingList`."""
-        results = Session.object_session(self).query(ContentFilter).filter(
+        results = store.query(ContentFilter).filter(
             ContentFilter.mailing_list == self,
             ContentFilter.filter_type == FilterType.filter_mime)
         for content_filter in results:
             yield content_filter.filter_pattern
 
     @filter_types.setter
-    def filter_types(self, sequence):
+    @dbconnection
+    def filter_types(self, store, sequence):
         """See `IMailingList`."""
         # First, delete all existing MIME type filter patterns.
-        store = Session.object_session(self)
         results = store.query(ContentFilter).filter(
             ContentFilter.mailing_list == self,
             ContentFilter.filter_type == FilterType.filter_mime)
@@ -371,19 +377,20 @@ class MailingList(Model):
             store.add(content_filter)
 
     @property
-    def pass_types(self):
+    @dbconnection
+    def pass_types(self, store):
         """See `IMailingList`."""
-        results = Session.object_session(self).query(ContentFilter).filter(
+        results = store.query(ContentFilter).filter(
             ContentFilter.mailing_list == self,
             ContentFilter.filter_type == FilterType.pass_mime)
         for content_filter in results:
             yield content_filter.filter_pattern
 
     @pass_types.setter
-    def pass_types(self, sequence):
+    @dbconnection
+    def pass_types(self, store, sequence):
         """See `IMailingList`."""
         # First, delete all existing MIME type pass patterns.
-        store = Session.object_session(self)
         results = store.query(ContentFilter).filter(
             ContentFilter.mailing_list == self,
             ContentFilter.filter_type == FilterType.pass_mime)
@@ -395,19 +402,20 @@ class MailingList(Model):
             store.add(content_filter)
 
     @property
-    def filter_extensions(self):
+    @dbconnection
+    def filter_extensions(self, store):
         """See `IMailingList`."""
-        results = Session.object_session(self).query(ContentFilter).filter(
+        results = store.query(ContentFilter).filter(
             ContentFilter.mailing_list == self,
             ContentFilter.filter_type == FilterType.filter_extension)
         for content_filter in results:
             yield content_filter.filter_pattern
 
     @filter_extensions.setter
-    def filter_extensions(self, sequence):
+    @dbconnection
+    def filter_extensions(self, store, sequence):
         """See `IMailingList`."""
         # First, delete all existing file extensions filter patterns.
-        store = Session.object_session(self)
         results = store.query(ContentFilter).filter(
             ContentFilter.mailing_list == self,
             ContentFilter.filter_type == FilterType.filter_extension)
@@ -419,19 +427,20 @@ class MailingList(Model):
             store.add(content_filter)
 
     @property
-    def pass_extensions(self):
+    @dbconnection
+    def pass_extensions(self, store):
         """See `IMailingList`."""
-        results = Session.object_session(self).query(ContentFilter).filter(
+        results = store.query(ContentFilter).filter(
             ContentFilter.mailing_list == self,
             ContentFilter.filter_type == FilterType.pass_extension)
         for content_filter in results:
             yield content_filter.pass_pattern
 
     @pass_extensions.setter
-    def pass_extensions(self, sequence):
+    @dbconnection
+    def pass_extensions(self, store, sequence):
         """See `IMailingList`."""
         # First, delete all existing file extensions pass patterns.
-        store = Session.object_session(self)
         results = store.query(ContentFilter).filter(
             ContentFilter.mailing_list == self,
             ContentFilter.filter_type == FilterType.pass_extension)
@@ -454,9 +463,9 @@ class MailingList(Model):
             raise TypeError(
                 'Undefined MemberRole: {0}'.format(role))
 
-    def subscribe(self, subscriber, role=MemberRole.member):
+    @dbconnection
+    def subscribe(self, store, subscriber, role=MemberRole.member):
         """See `IMailingList`."""
-        store = Session.object_session(self)
         if IAddress.providedBy(subscriber):
             member = store.query(Member).filter(
                 Member.role == role,
@@ -512,29 +521,30 @@ class AcceptableAliasSet:
     def __init__(self, mailing_list):
         self._mailing_list = mailing_list
 
-    def clear(self):
+    @dbconnection
+    def clear(self, store):
         """See `IAcceptableAliasSet`."""
-        Session.object_session(self._mailing_list).query(
-            AcceptableAlias).filter(
-                AcceptableAlias.mailing_list == self._mailing_list).delete()
+        store.query(AcceptableAlias).filter(
+            AcceptableAlias.mailing_list == self._mailing_list).delete()
 
-    def add(self, alias):
+    @dbconnection
+    def add(self, store, alias):
         if not (alias.startswith('^') or '@' in alias):
             raise ValueError(alias)
         alias = AcceptableAlias(self._mailing_list, alias.lower())
-        Session.object_session(self._mailing_list).add(alias)
+        store.add(alias)
 
-    def remove(self, alias):
-        Session.object_session(self._mailing_list).query(
-            AcceptableAlias).filter(
-                AcceptableAlias.mailing_list == self._mailing_list,
-                AcceptableAlias.alias == alias.lower()).delete()
+    @dbconnection
+    def remove(self, store, alias):
+        store.query(AcceptableAlias).filter(
+            AcceptableAlias.mailing_list == self._mailing_list,
+            AcceptableAlias.alias == alias.lower()).delete()
 
     @property
-    def aliases(self):
-        aliases = Session.object_session(self._mailing_list).query(
-            AcceptableAlias).filter(
-                AcceptableAlias.mailing_list_id == self._mailing_list.id)
+    @dbconnection
+    def aliases(self, store):
+        aliases = store.query(AcceptableAlias).filter(
+            AcceptableAlias.mailing_list_id == self._mailing_list.id)
         for alias in aliases:
             yield alias.alias
 
@@ -576,14 +586,14 @@ class ListArchiver(Model):
 
 @implementer(IListArchiverSet)
 class ListArchiverSet:
-    def __init__(self, mailing_list):
+    @dbconnection
+    def __init__(self, store, mailing_list):
         self._mailing_list = mailing_list
         system_archivers = {}
         for archiver in config.archivers:
             system_archivers[archiver.name] = archiver
         # Add any system enabled archivers which aren't already associated
         # with the mailing list.
-        store = Session.object_session(self._mailing_list)
         for archiver_name in system_archivers:
             exists = store.query(ListArchiver).filter(
                 ListArchiver.mailing_list == mailing_list,
@@ -593,14 +603,15 @@ class ListArchiverSet:
                                        system_archivers[archiver_name]))
 
     @property
-    def archivers(self):
-        entries = Session.object_session(self._mailing_list).query(
-            ListArchiver).filter(ListArchiver.mailing_list == self._mailing_list)
+    @dbconnection
+    def archivers(self, store):
+        entries = store.query(ListArchiver).filter(
+            ListArchiver.mailing_list == self._mailing_list)
         for entry in entries:
             yield entry
 
-    def get(self, archiver_name):
-        return Session.object_session(self._mailing_list).query(
-            ListArchiver).filter(
-                ListArchiver.mailing_list == self._mailing_list,
-                ListArchiver.name == archiver_name).first()
+    @dbconnection
+    def get(self, store, archiver_name):
+        return store.query(ListArchiver).filter(
+            ListArchiver.mailing_list == self._mailing_list,
+            ListArchiver.name == archiver_name).first()
diff --git a/src/mailman/model/member.py b/src/mailman/model/member.py
index f1007c311..9da9d5d0d 100644
--- a/src/mailman/model/member.py
+++ b/src/mailman/model/member.py
@@ -24,7 +24,7 @@ __all__ = [
     'Member',
     ]
 
-from sqlalchemy import Integer, Unicode, ForeignKey, Column
+from sqlalchemy import Column, ForeignKey, Integer, Unicode
 from sqlalchemy.orm import relationship
 from zope.component import getUtility
 from zope.event import notify
@@ -56,9 +56,9 @@ class Member(Model):
 
     id = Column(Integer, primary_key=True)
     _member_id = Column(UUID)
-    role = Column(Enum(enum=MemberRole))
+    role = Column(Enum(MemberRole))
     list_id = Column(Unicode)
-    moderation_action = Column(Enum(enum=Action))
+    moderation_action = Column(Enum(Action))
 
     address_id = Column(Integer, ForeignKey('address.id'))
     _address = relationship('Address')
diff --git a/src/mailman/model/message.py b/src/mailman/model/message.py
index 39f33aa89..74a76ac30 100644
--- a/src/mailman/model/message.py
+++ b/src/mailman/model/message.py
@@ -24,7 +24,7 @@ __all__ = [
     'Message',
     ]
 
-from sqlalchemy import Column, Integer, Unicode, LargeBinary
+from sqlalchemy import Column, Integer, LargeBinary, Unicode
 from zope.interface import implementer
 
 from mailman.database.model import Model
@@ -47,6 +47,7 @@ class Message(Model):
 
     @dbconnection
     def __init__(self, store, message_id, message_id_hash, path):
+        super(Message, self).__init__()
         self.message_id = message_id
         self.message_id_hash = message_id_hash
         self.path = path
diff --git a/src/mailman/model/messagestore.py b/src/mailman/model/messagestore.py
index f9f224dd6..0b8a0ac78 100644
--- a/src/mailman/model/messagestore.py
+++ b/src/mailman/model/messagestore.py
@@ -54,12 +54,13 @@ class MessageStore:
     def add(self, store, message):
         # Ensure that the message has the requisite headers.
         message_ids = message.get_all('message-id', [])
-        if len(message_ids) <> 1:
+        if len(message_ids) != 1:
             raise ValueError('Exactly one Message-ID header required')
         # Calculate and insert the X-Message-ID-Hash.
         message_id = message_ids[0]
         # Complain if the Message-ID already exists in the storage.
-        existing = store.query(Message).filter(Message.message_id == message_id).first()
+        existing = store.query(Message).filter(
+            Message.message_id == message_id).first()
         if existing is not None:
             raise ValueError(
                 'Message ID already exists in message store: {0}'.format(
@@ -80,9 +81,9 @@ class MessageStore:
         # providing a unique serial number, but to get this information, we
         # have to use a straight insert instead of relying on Elixir to create
         # the object.
-        row = Message(message_id=message_id,
-                      message_id_hash=hash32,
-                      path=relpath)
+        Message(message_id=message_id,
+                message_id_hash=hash32,
+                path=relpath)
         # Now calculate the full file system path.
         path = os.path.join(config.MESSAGES_DIR, relpath)
         # Write the file to the path, but catch the appropriate exception in
@@ -95,7 +96,7 @@ class MessageStore:
                     pickle.dump(message, fp, -1)
                     break
             except IOError as error:
-                if error.errno <> errno.ENOENT:
+                if error.errno != errno.ENOENT:
                     raise
             makedirs(os.path.dirname(path))
         return hash32
@@ -120,7 +121,8 @@ class MessageStore:
         # US-ASCII.
         if isinstance(message_id_hash, unicode):
             message_id_hash = message_id_hash.encode('ascii')
-        row = store.query(Message).filter_by(message_id_hash=message_id_hash).first()
+        row = store.query(Message).filter_by(
+            message_id_hash=message_id_hash).first()
         if row is None:
             return None
         return self._get_message(row)
diff --git a/src/mailman/model/mime.py b/src/mailman/model/mime.py
index 3eac4f07b..906af91ea 100644
--- a/src/mailman/model/mime.py
+++ b/src/mailman/model/mime.py
@@ -25,7 +25,7 @@ __all__ = [
     ]
 
 
-from sqlalchemy import Column, Integer, Unicode, ForeignKey
+from sqlalchemy import Column, ForeignKey, Integer, Unicode
 from sqlalchemy.orm import relationship
 from zope.interface import implementer
 
@@ -46,7 +46,7 @@ class ContentFilter(Model):
     mailing_list_id = Column(Integer, ForeignKey('mailinglist.id'))
     mailing_list = relationship('MailingList')
 
-    filter_type = Column(Enum(enum=FilterType))
+    filter_type = Column(Enum(FilterType))
     filter_pattern = Column(Unicode)
 
     def __init__(self, mailing_list, filter_pattern, filter_type):
diff --git a/src/mailman/model/pending.py b/src/mailman/model/pending.py
index 97d394721..a06a660b2 100644
--- a/src/mailman/model/pending.py
+++ b/src/mailman/model/pending.py
@@ -32,7 +32,7 @@ import hashlib
 
 from lazr.config import as_timedelta
 from sqlalchemy import (
-    Column, Integer, Unicode, ForeignKey, DateTime, LargeBinary)
+    Column, DateTime, ForeignKey, Integer, LargeBinary, Unicode)
 from sqlalchemy.orm import relationship
 from zope.interface import implementer
 from zope.interface.verify import verifyObject
@@ -71,6 +71,7 @@ class Pended(Model):
     __tablename__ = 'pended'
 
     def __init__(self, token, expiration_date):
+        super(Pended, self).__init__()
         self.token = token
         self.expiration_date = expiration_date
 
@@ -79,6 +80,7 @@ class Pended(Model):
     expiration_date = Column(DateTime)
     key_values = relationship('PendedKeyValue')
 
+
 
 @implementer(IPendable)
 class UnpendedPendable(dict):
@@ -119,9 +121,9 @@ class Pendings:
             expiration_date=now() + lifetime)
         for key, value in pendable.items():
             if isinstance(key, str):
-                key = unicode(key, 'utf-8')
+                key = key.encode('utf-8')
             if isinstance(value, str):
-                value = unicode(value, 'utf-8')
+                value = value.encode('utf-8')
             elif type(value) is int:
                 value = '__builtin__.int\1%s' % value
             elif type(value) is float:
@@ -150,8 +152,9 @@ class Pendings:
         pendable = UnpendedPendable()
         # Find all PendedKeyValue entries that are associated with the pending
         # object's ID.  Watch out for type conversions.
-        for keyvalue in store.query(PendedKeyValue).filter(
-                                   PendedKeyValue.pended_id == pending.id):
+        entries = store.query(PendedKeyValue).filter(
+            PendedKeyValue.pended_id == pending.id)
+        for keyvalue in entries:
             if keyvalue.value is not None and '\1' in keyvalue.value:
                 type_name, value = keyvalue.value.split('\1', 1)
                 pendable[keyvalue.key] = call_name(type_name, value)
@@ -171,7 +174,7 @@ class Pendings:
                 # Find all PendedKeyValue entries that are associated with the
                 # pending object's ID.
                 q = store.query(PendedKeyValue).filter(
-                               PendedKeyValue.pended_id == pending.id)
+                    PendedKeyValue.pended_id == pending.id)
                 for keyvalue in q:
                     store.delete(keyvalue)
                 store.delete(pending)
diff --git a/src/mailman/model/preferences.py b/src/mailman/model/preferences.py
index d74b17e30..1278f80b7 100644
--- a/src/mailman/model/preferences.py
+++ b/src/mailman/model/preferences.py
@@ -25,7 +25,7 @@ __all__ = [
     ]
 
 
-from sqlalchemy import Column, Integer, Unicode,  Boolean
+from sqlalchemy import Boolean, Column, Integer, Unicode
 from zope.component import getUtility
 from zope.interface import implementer
 
@@ -49,8 +49,8 @@ class Preferences(Model):
     _preferred_language = Column('preferred_language', Unicode)
     receive_list_copy = Column(Boolean)
     receive_own_postings = Column(Boolean)
-    delivery_mode = Column(Enum(enum=DeliveryMode))
-    delivery_status = Column(Enum(enum=DeliveryStatus))
+    delivery_mode = Column(Enum(DeliveryMode))
+    delivery_status = Column(Enum(DeliveryStatus))
 
     def __repr__(self):
         return '<Preferences object at {0:#x}>'.format(id(self))
diff --git a/src/mailman/model/requests.py b/src/mailman/model/requests.py
index 3d15ddea9..335e1e002 100644
--- a/src/mailman/model/requests.py
+++ b/src/mailman/model/requests.py
@@ -26,7 +26,7 @@ __all__ = [
 
 from cPickle import dumps, loads
 from datetime import timedelta
-from sqlalchemy import Column, Unicode, Integer, ForeignKey, LargeBinary
+from sqlalchemy import Column, ForeignKey, Integer, LargeBinary, Unicode
 from sqlalchemy.orm import relationship
 from zope.component import getUtility
 from zope.interface import implementer
@@ -69,7 +69,8 @@ class ListRequests:
     @property
     @dbconnection
     def count(self, store):
-        return store.query(_Request).filter_by(mailing_list=self.mailing_list).count()
+        return store.query(_Request).filter_by(
+            mailing_list=self.mailing_list).count()
 
     @dbconnection
     def count_of(self, store, request_type):
@@ -79,7 +80,8 @@ class ListRequests:
     @property
     @dbconnection
     def held_requests(self, store):
-        results = store.query(_Request).filter_by(mailing_list=self.mailing_list)
+        results = store.query(_Request).filter_by(
+            mailing_list=self.mailing_list)
         for request in results:
             yield request
 
@@ -148,13 +150,14 @@ class _Request(Model):
 
     id = Column(Integer, primary_key=True)# TODO: ???, default=AutoReload)
     key = Column(Unicode)
-    request_type = Column(Enum(enum=RequestType))
+    request_type = Column(Enum(RequestType))
     data_hash = Column(LargeBinary)
 
     mailing_list_id = Column(Integer, ForeignKey('mailinglist.id'))
     mailing_list = relationship('MailingList')
 
     def __init__(self, key, request_type, mailing_list, data_hash):
+        super(_Request, self).__init__()
         self.key = key
         self.request_type = request_type
         self.mailing_list = mailing_list
diff --git a/src/mailman/model/roster.py b/src/mailman/model/roster.py
index a9a396523..a6cbeb104 100644
--- a/src/mailman/model/roster.py
+++ b/src/mailman/model/roster.py
@@ -161,7 +161,7 @@ class AdministratorRoster(AbstractRoster):
         return store.query(Member).filter(
             Member.list_id == self._mlist.list_id,
             or_(Member.role == MemberRole.owner,
-               Member.role == MemberRole.moderator))
+                Member.role == MemberRole.moderator))
 
     @dbconnection
     def get_member(self, store, address):
@@ -169,7 +169,7 @@ class AdministratorRoster(AbstractRoster):
         results = store.query(Member).filter(
                 Member.list_id == self._mlist.list_id,
                 or_(Member.role == MemberRole.moderator,
-                   Member.role == MemberRole.owner),
+                    Member.role == MemberRole.owner),
                 Address.email == address,
                 Member.address_id == Address.id)
         if results.count() == 0:
diff --git a/src/mailman/model/tests/test_listmanager.py b/src/mailman/model/tests/test_listmanager.py
index 3951e8250..b290138f3 100644
--- a/src/mailman/model/tests/test_listmanager.py
+++ b/src/mailman/model/tests/test_listmanager.py
@@ -29,11 +29,11 @@ __all__ = [
 
 import unittest
 
-from sqlalchemy.orm import sessionmaker
 from zope.component import getUtility
 
 from mailman.app.lifecycle import create_list
 from mailman.app.moderator import hold_message
+from mailman.config import config
 from mailman.interfaces.listmanager import (
     IListManager, ListCreatedEvent, ListCreatingEvent, ListDeletedEvent,
     ListDeletingEvent)
@@ -148,9 +148,8 @@ Message-ID: <argon>
         for name in filter_names:
             setattr(self._ant, name, ['test-filter-1', 'test-filter-2'])
         getUtility(IListManager).delete(self._ant)
-        Session = sessionmaker()
-        store = Session.object_session(self._ant)
-        filters = store.query(ContentFilter).filter_by(mailing_list = self._ant)
+        filters = config.db.store.query(ContentFilter).filter_by(
+            mailing_list = self._ant)
         self.assertEqual(filters.count(), 0)
 
 
diff --git a/src/mailman/model/uid.py b/src/mailman/model/uid.py
index 77f1b59bb..29d8e7021 100644
--- a/src/mailman/model/uid.py
+++ b/src/mailman/model/uid.py
@@ -29,8 +29,8 @@ __all__ = [
 from sqlalchemy import Column, Integer
 
 from mailman.database.model import Model
-from mailman.database.types import UUID
 from mailman.database.transaction import dbconnection
+from mailman.database.types import UUID
 
 
 
@@ -54,6 +54,7 @@ class UID(Model):
 
     @dbconnection
     def __init__(self, store, uid):
+        super(UID, self).__init__()
         self.uid = uid
         store.add(self)
 
diff --git a/src/mailman/model/user.py b/src/mailman/model/user.py
index cd47a5dac..576015dbe 100644
--- a/src/mailman/model/user.py
+++ b/src/mailman/model/user.py
@@ -25,7 +25,7 @@ __all__ = [
     ]
 
 from sqlalchemy import (
-    Column, Unicode, Integer, DateTime, ForeignKey, LargeBinary)
+    Column, DateTime, ForeignKey, Integer, LargeBinary, Unicode)
 from sqlalchemy.orm import relationship, backref
 from zope.event import notify
 from zope.interface import implementer
@@ -60,25 +60,24 @@ class User(Model):
     _user_id = Column(UUID)
     _created_on = Column(DateTime)
 
-    addresses = relationship('Address',
-                             backref='user',
-                             primaryjoin=
-                                 id==Address.user_id)
+    addresses = relationship(
+        'Address', backref='user',
+        primaryjoin=(id==Address.user_id))
 
-    _preferred_address_id = Column(Integer, ForeignKey('address.id',
-                                                       use_alter=True,
-                                                       name='_preferred_address'))
-    _preferred_address = relationship('Address',
-                                      primaryjoin=
-                                          _preferred_address_id==Address.id,
-                                      post_update=True)
+    _preferred_address_id = Column(
+        Integer,
+        ForeignKey('address.id', use_alter=True, name='_preferred_address'))
+    _preferred_address = relationship(
+        'Address', primaryjoin=(_preferred_address_id==Address.id),
+        post_update=True)
 
     preferences_id = Column(Integer, ForeignKey('preferences.id'))
-    preferences = relationship('Preferences',
-                               backref=backref('user', uselist=False))
+    preferences = relationship(
+        'Preferences', backref=backref('user', uselist=False))
 
     @dbconnection
     def __init__(self, store, display_name=None, preferences=None):
+        super(User, self).__init__()
         self._created_on = date_factory.now()
         user_id = uid_factory.new_uid()
         assert store.query(User).filter_by(_user_id=user_id).count() == 0, (
diff --git a/src/mailman/model/version.py b/src/mailman/model/version.py
index 95cf03dac..ecef6ed8a 100644
--- a/src/mailman/model/version.py
+++ b/src/mailman/model/version.py
@@ -24,9 +24,9 @@ __all__ = [
     'Version',
     ]
 
-from sqlalchemy import Column, Unicode, Integer
 
 from mailman.database.model import Model
+from sqlalchemy import Column, Integer, Unicode
 
 
 
@@ -43,5 +43,6 @@ class Version(Model):
     PRESERVE = True
 
     def __init__(self, component, version):
+        super(Version, self).__init__()
         self.component = component
         self.version = version
diff --git a/src/mailman/utilities/importer.py b/src/mailman/utilities/importer.py
index 9856a8223..26b7261e3 100644
--- a/src/mailman/utilities/importer.py
+++ b/src/mailman/utilities/importer.py
@@ -186,7 +186,6 @@ NAME_MAPPINGS = dict(
     filter_mime_types='filter_types',
     generic_nonmember_action='default_nonmember_action',
     include_list_post_header='allow_list_posts',
-    last_post_time='last_post_at',
     member_moderation_action='default_member_action',
     mod_password='moderator_password',
     news_moderation='newsgroup_moderation',
@@ -198,13 +197,13 @@ NAME_MAPPINGS = dict(
     send_welcome_msg='send_welcome_message',
     )
 
-# Datetime Fields that need a type conversion to python datetime
-# object for SQLite database.
-DATETIME_OBJECTS = [
+# These DateTime fields of the mailinglist table need a type conversion to
+# Python datetime object for SQLite databases.
+DATETIME_COLUMNS = [
     'created_at',
     'digest_last_sent_at',
     'last_post_time',
-]
+    ]
 
 EXCLUDES = set((
     'digest_members',
@@ -225,8 +224,8 @@ def import_config_pck(mlist, config_dict):
         # Some attributes must not be directly imported.
         if key in EXCLUDES:
             continue
-        # Created at must not be set, it needs a type conversion
-        if key in DATETIME_OBJECTS:
+        # These objects need explicit type conversions.
+        if key in DATETIME_COLUMNS:
             continue
         # Some attributes from Mailman 2 were renamed in Mailman 3.
         key = NAME_MAPPINGS.get(key, key)
@@ -249,7 +248,7 @@ def import_config_pck(mlist, config_dict):
             except (TypeError, KeyError):
                 print('Type conversion error for key "{}": {}'.format(
                     key, value), file=sys.stderr)
-    for key in DATETIME_OBJECTS:
+    for key in DATETIME_COLUMNS:
         try:
             value = datetime.datetime.utcfromtimestamp(config_dict[key])
         except KeyError: