Fixed #20793 -- Added Last-Modified header to sitemaps.

django/contrib/sitemaps/__init__.py

@@ -86,17 +86,27 @@ class Sitemap(object):
         domain = site.domain
 
         urls = []
+        latest_lastmod = None
+        all_items_lastmod = True  # track if all items have a lastmod
         for item in self.paginator.page(page).object_list:
             loc = "%s://%s%s" % (protocol, domain, self.__get('location', item))
             priority = self.__get('priority', item, None)
+            lastmod = self.__get('lastmod', item, None)
+            if all_items_lastmod:
+                all_items_lastmod = lastmod is not None
+                if (all_items_lastmod and
+                    (latest_lastmod is None or lastmod > latest_lastmod)):
+                    latest_lastmod = lastmod
             url_info = {
                 'item':       item,
                 'location':   loc,
-                'lastmod':    self.__get('lastmod', item, None),
+                'lastmod':    lastmod,
                 'changefreq': self.__get('changefreq', item, None),
                 'priority':   str(priority if priority is not None else ''),
             }
             urls.append(url_info)
+        if all_items_lastmod:
+            self.latest_lastmod = latest_lastmod
         return urls
 
 class FlatPageSitemap(Sitemap):

django/contrib/sitemaps/tests/test_http.py

@@ -77,6 +77,21 @@ class HTTPSitemapTests(SitemapTestsBase):
 """ % (self.base_url, date.today())
         self.assertXMLEqual(response.content.decode('utf-8'), expected_content)
 
+    def test_sitemap_last_modified(self):
+        "Tests that Last-Modified header is set correctly"
+        response = self.client.get('/lastmod/sitemap.xml')
+        self.assertEqual(response['Last-Modified'], 'Wed, 13 Mar 2013 10:00:00 GMT')
+
+    def test_sitemap_last_modified_missing(self):
+        "Tests that Last-Modified header is missing when sitemap has no lastmod"
+        response = self.client.get('/generic/sitemap.xml')
+        self.assertFalse(response.has_header('Last-Modified'))
+
+    def test_sitemap_last_modified_mixed(self):
+        "Tests that Last-Modified header is omitted when lastmod not on all items"
+        response = self.client.get('/lastmod-mixed/sitemap.xml')
+        self.assertFalse(response.has_header('Last-Modified'))
+
     @skipUnless(settings.USE_I18N, "Internationalization is not enabled")
     @override_settings(USE_L10N=True)
     def test_localized_priority(self):

django/contrib/sitemaps/tests/urls/http.py

@@ -15,10 +15,36 @@ class SimpleSitemap(Sitemap):
     def items(self):
         return [object()]
 
+
+class FixedLastmodSitemap(SimpleSitemap):
+    lastmod = datetime(2013, 3, 13, 10, 0, 0)
+
+
+class FixedLastmodMixedSitemap(Sitemap):
+    changefreq = "never"
+    priority = 0.5
+    location = '/location/'
+    loop = 0
+
+    def items(self):
+        o1 = TestModel()
+        o1.lastmod = datetime(2013, 3, 13, 10, 0, 0)
+        o2 = TestModel()
+        return [o1, o2]
+
+
 simple_sitemaps = {
     'simple': SimpleSitemap,
 }
 
+fixed_lastmod_sitemaps = {
+    'fixed-lastmod': FixedLastmodSitemap,
+}
+
+fixed_lastmod__mixed_sitemaps = {
+    'fixed-lastmod-mixed': FixedLastmodMixedSitemap,
+}
+
 generic_sitemaps = {
     'generic': GenericSitemap({'queryset': TestModel.objects.all()}),
 }
@@ -36,6 +62,8 @@ urlpatterns = patterns('django.contrib.sitemaps.views',
     (r'^simple/sitemap\.xml$', 'sitemap', {'sitemaps': simple_sitemaps}),
     (r'^simple/custom-sitemap\.xml$', 'sitemap',
         {'sitemaps': simple_sitemaps, 'template_name': 'custom_sitemap.xml'}),
+    (r'^lastmod/sitemap\.xml$', 'sitemap', {'sitemaps': fixed_lastmod_sitemaps}),
+    (r'^lastmod-mixed/sitemap\.xml$', 'sitemap', {'sitemaps': fixed_lastmod__mixed_sitemaps}),
     (r'^generic/sitemap\.xml$', 'sitemap', {'sitemaps': generic_sitemaps}),
     (r'^flatpages/sitemap\.xml$', 'sitemap', {'sitemaps': flatpage_sitemaps}),
     url(r'^cached/index\.xml$', cache_page(1)(views.index),

django/contrib/sitemaps/views.py

@@ -1,3 +1,4 @@
+from calendar import timegm
 from functools import wraps
 
 from django.contrib.sites.models import get_current_site
@@ -6,6 +7,7 @@ from django.core.paginator import EmptyPage, PageNotAnInteger
 from django.http import Http404
 from django.template.response import TemplateResponse
 from django.utils import six
+from django.utils.http import http_date
 
 def x_robots_tag(func):
     @wraps(func)
@@ -64,5 +66,11 @@ def sitemap(request, sitemaps, section=None,
             raise Http404("Page %s empty" % page)
         except PageNotAnInteger:
             raise Http404("No page '%s'" % page)
-    return TemplateResponse(request, template_name, {'urlset': urls},
-                            content_type=content_type)
+    response = TemplateResponse(request, template_name, {'urlset': urls},
+                                content_type=content_type)
+    if hasattr(site, 'latest_lastmod'):
+        # if latest_lastmod is defined for site, set header so as
+        # ConditionalGetMiddleware is able to send 304 NOT MODIFIED
+        response['Last-Modified'] = http_date(
+            timegm(site.latest_lastmod.utctimetuple()))
+    return response

docs/ref/contrib/sitemaps.txt

@@ -178,6 +178,15 @@ Sitemap class reference
         representing the last-modified date/time for *every* object returned by
         :attr:`~Sitemap.items()`.
 
+        .. versionadded:: 1.7
+
+        If all items in a sitemap have a :attr:`~Sitemap.lastmod`, the sitemap
+        generated by :func:`views.sitemap` will have a ``Last-Modified``
+        header equal to the latest ``lastmod``. You can activate the
+        :class:`~django.middleware.http.ConditionalGetMiddleware` to make
+        Django respond appropriately to requests with an ``If-Modified-Since``
+        header which will prevent sending the sitemap if it hasn't changed.
+
     .. attribute:: Sitemap.changefreq
 
         **Optional.** Either a method or attribute.

docs/releases/1.7.txt

@@ -95,6 +95,12 @@ Minor features
 * The :djadminopt:`--no-color` option for ``django-admin.py`` allows you to
   disable the colorization of management command output.
 
+* The :mod:`sitemap framework<django.contrib.sitemaps>` now makes use of
+  :attr:`~django.contrib.sitemaps.Sitemap.lastmod` to set a ``Last-Modified``
+  header in the response. This makes it possible for the
+  :class:`~django.middleware.http.ConditionalGetMiddleware` to handle
+  conditional ``GET`` requests for sitemaps which set ``lastmod``.
+
 Backwards incompatible changes in 1.7
 =====================================