Doc'd that UpdateCacheMiddleware and cache_page affect downstream caches.
Thanks to Nick Pope for review.
@@ -530,8 +530,9 @@ cached separately. This middleware expects that a HEAD request is answered with
the same response headers as the corresponding GET request; in which case it can
return a cached GET response for HEAD request.
-Additionally, ``UpdateCacheMiddleware`` automatically sets a few headers in each
-:class:`~django.http.HttpResponse`:
+Additionally, ``UpdateCacheMiddleware`` automatically sets a few headers in
+each :class:`~django.http.HttpResponse` which affect :ref:`downstream caches
+<downstream-caches>`:
* Sets the ``Expires`` header to the current date/time plus the defined
:setting:`CACHE_MIDDLEWARE_SECONDS`.
@@ -621,6 +622,10 @@ The ``key_prefix`` and ``cache`` arguments may be specified together. The
``key_prefix`` argument and the :setting:`KEY_PREFIX <CACHES-KEY_PREFIX>`
specified under :setting:`CACHES` will be concatenated.
+Additionally, ``cache_page`` automatically sets ``Cache-Control`` and
+``Expires`` headers in the response which affect :ref:`downstream caches
+<downstream-caches>`.
+
.. versionchanged:: 3.1
In older versions, the ``max-age`` directive from the ``Cache-Control``
@@ -1109,6 +1114,8 @@ instance, to do this for the ``locmem`` backend, put this code in a module::
...and use the dotted Python path to this class in the
:setting:`BACKEND <CACHES-BACKEND>` portion of your :setting:`CACHES` setting.
+.. _downstream-caches:
+
Downstream caches
=================
