Source code for sqlalchemy_utils.types.timezone

import six
from sqlalchemy import types

from ..exceptions import ImproperlyConfigured
from .scalar_coercible import ScalarCoercible


[docs]class TimezoneType(types.TypeDecorator, ScalarCoercible): """ TimezoneType provides a way for saving timezones (from either the pytz or the dateutil package) objects into database. TimezoneType saves timezone objects as strings on the way in and converts them back to objects when querying the database. :: from sqlalchemy_utils import TimezoneType class User(Base): __tablename__ = 'user' # Pass backend='pytz' to change it to use pytz (dateutil by # default) timezone = sa.Column(TimezoneType(backend='pytz')) """ impl = types.Unicode(50) python_type = None def __init__(self, backend='dateutil'): """ :param backend: Whether to use 'dateutil' or 'pytz' for timezones. """ self.backend = backend if backend == 'dateutil': try: from dateutil.tz import tzfile from dateutil.zoneinfo import gettz self.python_type = tzfile self._to = gettz self._from = lambda x: six.text_type(x._filename) except ImportError: raise ImproperlyConfigured( "'python-dateutil' is required to use the " "'dateutil' backend for 'TimezoneType'" ) elif backend == 'pytz': try: from pytz import timezone from pytz.tzinfo import BaseTzInfo self.python_type = BaseTzInfo self._to = timezone self._from = six.text_type except ImportError: raise ImproperlyConfigured( "'pytz' is required to use the 'pytz' backend " "for 'TimezoneType'" ) else: raise ImproperlyConfigured( "'pytz' or 'dateutil' are the backends supported for " "'TimezoneType'" ) def _coerce(self, value): if value is not None and not isinstance(value, self.python_type): obj = self._to(value) if obj is None: raise ValueError("unknown time zone '%s'" % value) return obj return value def process_bind_param(self, value, dialect): return self._from(self._coerce(value)) if value else None def process_result_value(self, value, dialect): return self._to(value) if value else None