Ticket #3680: cache.control.on.syndication.code.only.diff

django/contrib/syndication/views.py

@@ -1 +1 @@
 from django.contrib.syndication import feeds
 from django.http import HttpResponse, Http404
+from django.middleware.http import response_304_if_cached
 
 def feed(request, url, feed_dict=None):
     if not feed_dict:
@@ -15 +16 @@
     except KeyError:
         raise Http404, "Slug %r isn't registered." % slug
 
+    feed = f(slug, request.path)
+
+    response = HttpResponse()
+
+    # Give the feed a chance to pull cache control data from
+    # somewhere without even retrieving the objects, like from a cache.
     try:
-        feedgen = f(slug, request.path).get_feed(param)
+        etag, last_modified = feed.cache_control_from_bits(param)
+        if etag:
+            response['ETag'] = etag
+        if last_modified:
+            response['Last-Modified'] = last_modified.strftime('%a, %d %b %Y %H:%M:%S GMT')
+
+        if response_304_if_cached(request, response):
+            return response
+    except AttributeError:
+        # No .cache_control_from_bits method
+        pass
+
+    try:
+        feedgen = feed.get_feed(param)
     except feeds.FeedDoesNotExist:
         raise Http404, "Invalid feed parameters. Slug %r is valid, but other parameters, or lack thereof, are not." % slug
 
-    response = HttpResponse(mimetype=feedgen.mime_type)
+    response.mimetype = feedgen.mime_type
+
+    # See if we can bail out before generating the text of the feed
+    try:
+        etag, last_modified = feed.cache_control(feed._raw_items)
+        if etag:
+            response['ETag'] = etag
+        if last_modified:
+            response['Last-Modified'] = last_modified.strftime('%a, %d %b %Y %H:%M:%S GMT')
+
+        if response_304_if_cached(request, response):
+            return response
+    except AttributeError:
+        # no cache_control method
+        raise
+        pass
+
+    feed.process_items()
     feedgen.write(response, 'utf-8')
     return response

django/contrib/syndication/feeds.py

@@ -24 +24 @@
         self.feed_url = feed_url
         self.title_template_name = self.title_template or ('feeds/%s_title.html' % slug)
         self.description_template_name = self.description_template or ('feeds/%s_description.html' % slug)
+        self.__items = None
 
     def item_link(self, item):
         try:
@@ -64 +65 @@
         else:
             obj = None
 
-        current_site = Site.objects.get_current()
+        self.current_site = current_site = Site.objects.get_current()
         link = self.__get_dynamic_attr('link', obj)
         link = add_domain(current_site.domain, link)
 
@@ -81 +82 @@
             feed_copyright = self.__get_dynamic_attr('feed_copyright', obj),
         )
 
+        self._raw_items = self.__get_dynamic_attr('items', obj)
+        self.feed = feed
+        return feed
+
+    def process_items(self):
+        current_site = self.current_site
+        feed = self.feed
+
         try:
             title_tmp = loader.get_template(self.title_template_name)
         except TemplateDoesNotExist:
@@ -90 +99 @@
         except TemplateDoesNotExist:
             description_tmp = Template('{{ obj }}')
 
-        for item in self.__get_dynamic_attr('items', obj):
+        for item in self._raw_items:
             link = add_domain(current_site.domain, self.__get_dynamic_attr('item_link', item))
             enc = None
             enc_url = self.__get_dynamic_attr('item_enclosure_url', item)

django/middleware/http.py

@@ -1 +1 @@
 import datetime
 
+def response_304_if_cached(request, response):
+    """Given the etag and last_modified passed in, modifies the
+    response inline to make it return a 304 if appropriate.
+    Returns true if a cached response was created."""
+    if response.has_header('ETag'):
+        if_none_match = request.META.get('HTTP_IF_NONE_MATCH', None)
+        if if_none_match == response['ETag']:
+            response.status_code = 304
+            response.content = ''
+            response['Content-Length'] = '0'
+            return True
+
+    if response.has_header('Last-Modified'):
+        last_mod = response['Last-Modified']
+        if_modified_since = request.META.get('HTTP_IF_MODIFIED_SINCE', None)
+        if if_modified_since == response['Last-Modified']:
+            response.status_code = 304
+            response.content = ''
+            response['Content-Length'] = '0'
+            return True
+
+    if request.method == 'HEAD':
+        response.content = ''
+
+    return False
+
 class ConditionalGetMiddleware(object):
     """
     Handles conditional GET operations. If the response has a ETag or
@@ -13 +39 @@
     def process_response(self, request, response):
         now = datetime.datetime.utcnow()
         response['Date'] = now.strftime('%a, %d %b %Y %H:%M:%S GMT')
+
         if not response.has_header('Content-Length'):
             response['Content-Length'] = str(len(response.content))
 
-        if response.has_header('ETag'):
-            if_none_match = request.META.get('HTTP_IF_NONE_MATCH', None)
-            if if_none_match == response['ETag']:
-                response.status_code = 304
-                response.content = ''
-                response['Content-Length'] = '0'
-
-        if response.has_header('Last-Modified'):
-            last_mod = response['Last-Modified']
-            if_modified_since = request.META.get('HTTP_IF_MODIFIED_SINCE', None)
-            if if_modified_since == response['Last-Modified']:
-                response.status_code = 304
-                response.content = ''
-                response['Content-Length'] = '0'
-
-        if request.method == 'HEAD':
-            response.content = ''
-
+        response_304_if_cached(request, response)
+        
         return response
 
 class SetRemoteAddrFromForwardedFor(object):