From 9e07a9b5feb30fe06fb23d0e77edd34f6c3f92b5 Mon Sep 17 00:00:00 2001
From: Rinat Khabibiev <srenskiy@gmail.com>
Date: Thu, 15 Sep 2016 11:10:21 +0300
Subject: [PATCH] Fixed #27226 -- Removed patch_response_headers()'s setting of
the Last-Modified header.
---
django/utils/cache.py | 6 ++----
docs/ref/utils.txt | 5 ++++-
docs/releases/1.11.txt | 8 ++++++++
docs/topics/cache.txt | 7 ++++---
4 files changed, 18 insertions(+), 8 deletions(-)
diff --git a/django/utils/cache.py b/django/utils/cache.py
index ac469195da..e74bfbea5d 100644
--- a/django/utils/cache.py
+++ b/django/utils/cache.py
@@ -229,8 +229,8 @@ def _if_modified_since_passes(last_modified, if_modified_since):
def patch_response_headers(response, cache_timeout=None):
"""
- Adds some useful headers to the given HttpResponse object:
- ETag, Last-Modified, Expires and Cache-Control
+ Add HTTP caching headers to the given HttpResponse: Expires and
+ Cache-Control.
Each header is only added if it isn't already set.
@@ -246,8 +246,6 @@ def patch_response_headers(response, cache_timeout=None):
response.add_post_render_callback(set_response_etag)
else:
response = set_response_etag(response)
- if not response.has_header('Last-Modified'):
- response['Last-Modified'] = http_date()
if not response.has_header('Expires'):
response['Expires'] = http_date(time.time() + cache_timeout)
patch_cache_control(response, max_age=cache_timeout)
diff --git a/docs/ref/utils.txt b/docs/ref/utils.txt
index 00ac7970d7..a9072f9442 100644
--- a/docs/ref/utils.txt
+++ b/docs/ref/utils.txt
@@ -53,7 +53,6 @@ need to distinguish caches by the ``Accept-language`` header.
Adds some useful headers to the given ``HttpResponse`` object:
* ``ETag``
- * ``Last-Modified``
* ``Expires``
* ``Cache-Control``
@@ -62,6 +61,10 @@ need to distinguish caches by the ``Accept-language`` header.
``cache_timeout`` is in seconds. The :setting:`CACHE_MIDDLEWARE_SECONDS`
setting is used by default.
+ .. versionchanged:: 1.11
+
+ In older versions, the ``Last-Modified`` header was also set.
+
.. function:: add_never_cache_headers(response)
Adds a ``Cache-Control: max-age=0, no-cache, no-store, must-revalidate``
diff --git a/docs/releases/1.11.txt b/docs/releases/1.11.txt
index 411c6fb3ab..a9de4b095b 100644
--- a/docs/releases/1.11.txt
+++ b/docs/releases/1.11.txt
@@ -539,6 +539,14 @@ Miscellaneous
:rfc:`7232` Conditional Requests specification rather than the older
:rfc:`2616`.
+* :func:`~django.utils.cache.patch_response_headers` no longer adds a
+ ``Last-Modified`` header. According to the :rfc:`7234#section-4.2.2`, this
+ header is useless alongside other caching headers that provide an explicit
+ expiration time, e.g. ``Expires`` or ``Cache-Control``.
+ :class:`~django.middleware.cache.UpdateCacheMiddleware` and
+ :func:`~django.utils.cache.add_never_cache_headers` call
+ ``patch_response_headers()`` and therefore are also affected by this change.
+
* In the admin templates, ``<p class="help">`` is replaced with a ``<div>`` tag
to allow including lists inside help text.
diff --git a/docs/topics/cache.txt b/docs/topics/cache.txt
index 2a48a66abe..ec90d89bba 100644
--- a/docs/topics/cache.txt
+++ b/docs/topics/cache.txt
@@ -528,15 +528,16 @@ return a cached GET response for HEAD request.
Additionally, ``UpdateCacheMiddleware`` automatically sets a few headers in each
:class:`~django.http.HttpResponse`:
-* Sets the ``Last-Modified`` header to the current date/time when a fresh
- (not cached) version of the page is requested.
-
* Sets the ``Expires`` header to the current date/time plus the defined
:setting:`CACHE_MIDDLEWARE_SECONDS`.
* Sets the ``Cache-Control`` header to give a max age for the page --
again, from the :setting:`CACHE_MIDDLEWARE_SECONDS` setting.
+.. versionchanged:: 1.11
+
+ In older versions, the ``Last-Modified`` header was also set.
+
See :doc:`/topics/http/middleware` for more on middleware.
If a view sets its own cache expiry time (i.e. it has a ``max-age`` section in