# Copyright 2023 Reid Swanson.
#
# This file is part of scrachy.
#
# scrachy is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# scrachy is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with scrachy. If not, see <https://www.gnu.org/licenses/>.
"""
Custom SqlAlchemy types.
"""
# Python Modules
import datetime
# 3rd Party Modules
from sqlalchemy import TypeDecorator
from sqlalchemy.types import TIMESTAMP
# Project Modules
LOCAL_TIMEZONE = datetime.datetime.utcnow().astimezone().tzinfo
[docs]
class TimeStampTZ(TypeDecorator):
"""
A custom timestamp type that ensures all datetimes are timezone aware
before entering or exiting the database.
"""
# See: https://mike.depalatis.net/blog/sqlalchemy-timestamps.html
impl = TIMESTAMP
# This might produce different results if the local timezone changes,
# but that shouldn't happen while running.
cache_ok = True
[docs]
def __init__(self, timezone: bool = False):
super().__init__(timezone)
@property
def python_type(self):
return datetime.datetime
[docs]
def process_literal_param(self, value, dialect):
if value.tzinfo is None:
value = value.astimezone(LOCAL_TIMEZONE)
return value.astimezone(datetime.timezone.utc)
[docs]
def process_bind_param(self, value: datetime, dialect):
if value.tzinfo is None:
value = value.astimezone(LOCAL_TIMEZONE)
return value.astimezone(datetime.timezone.utc)
[docs]
def process_result_value(self, value, dialect):
if value.tzinfo is None:
return value.replace(tzinfo=datetime.timezone.utc)
return value.astimezone(datetime.timezone.utc)