#!/usr/bin/env python
# cardinal_pythonlib/cache_mw.py
"""
===============================================================================
Original code copyright (C) 2009-2022 Rudolf Cardinal (rudolf@pobox.com).
This file is part of cardinal_pythonlib.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
https://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
===============================================================================
**WSGI middleware to disable client-side caching.**
"""
from cardinal_pythonlib.logs import get_brace_style_log_with_null_handler
from cardinal_pythonlib.wsgi.constants import (
TYPE_WSGI_APP,
TYPE_WSGI_APP_RESULT,
TYPE_WSGI_ENVIRON,
TYPE_WSGI_EXC_INFO,
TYPE_WSGI_RESPONSE_HEADERS,
TYPE_WSGI_START_RESPONSE,
TYPE_WSGI_START_RESP_RESULT,
TYPE_WSGI_STATUS,
)
log = get_brace_style_log_with_null_handler(__name__)
# log.setLevel(logging.DEBUG)
# =============================================================================
# DisableClientSideCachingMiddleware
# =============================================================================
# https://stackoverflow.com/questions/49547/making-sure-a-web-page-is-not-cached-across-all-browsers # noqa: E501
# https://stackoverflow.com/questions/3859097/how-to-add-http-headers-in-wsgi-middleware # noqa: E501
[docs]class DisableClientSideCachingMiddleware(object):
"""
WSGI middleware to disable client-side caching.
"""
def __init__(self, app: TYPE_WSGI_APP) -> None:
self.app = app
def __call__(
self,
environ: TYPE_WSGI_ENVIRON,
start_response: TYPE_WSGI_START_RESPONSE,
) -> TYPE_WSGI_APP_RESULT:
def custom_start_response(
status: TYPE_WSGI_STATUS,
headers: TYPE_WSGI_RESPONSE_HEADERS,
exc_info: TYPE_WSGI_EXC_INFO = None,
) -> TYPE_WSGI_START_RESP_RESULT:
add_never_cache_headers(headers)
log.debug("HTTP status {}, headers {}", status, headers)
return start_response(status, headers, exc_info)
return self.app(environ, custom_start_response)