tz-sqlalchemy.py

from sqlalchemy.types import DATETIME  # optionally import this from your specific dialect
from sqlalchemy.types import TypeDecorator
import datetime
import pytz

class TzDateTime(TypeDecorator):
    impl = DATETIME
    tz = pytz.utc

    def process_bind_param(self, value, dialect):
        if value is None:
            return None
        if not isinstance(value, datetime.datetime):
            raise TypeError("%r is not an instance of %r" % (value, datetime.datetime))
        if value.tzinfo is None:
            raise TypeError("%r is a naive datetime" % value)
        localized = self.tz.normalize(value.astimezone(self.tz))
        return localized.replace(tzinfo=None)

    def process_result_value(self, value, dialect):
        if value is None:
            return None
        if not isinstance(value, datetime.datetime):
            raise TypeError("%r is not an instance of %r" % (value, datetime.datetime))
        if value.tzinfo is not None:
            raise TypeError("%r is not a naive datetime" % value)
        return self.tz.localize(value)

    @classmethod
    def now(self):
        return datetime.datetime.now(self.tz)