Drive the news entry on the topbar from PinnedNewsArticle

This will generate a query for every single page on the site in
development mode, but that's OK - in production we're using ESI and will
cache the result of it.

Author: mhagander

pgweb/news/models.py

@@ -58,6 +58,9 @@ def purge_urls(self):
         yield '/news/.*.rss'
         # FIXME: when to expire the front page?
         yield '/$'
+        # If this is the pinned article, we need to purge the include
+        if self.pinnednewsarticle_set.exists():
+            yield '/include/topbar/'
 
     def __str__(self):
         return "%s: %s" % (self.date, self.title)
@@ -132,6 +135,8 @@ class PinnedNewsArticle(models.Model):
     pinnedarticle = models.ForeignKey(NewsArticle, null=True, blank=True, on_delete=models.SET_NULL)
     pinnedtoproviders = models.JSONField(null=False, blank=True, default=dict)
 
+    purge_urls = ('/include/topbar/', )
+
     def save(self, *args, **kwargs):
         if not self.pk and PinnedNewsArticle.objects.exists():
             raise ValidationError("Only one PinnedNewsArticle may exist!")

pgweb/util/contexts.py

@@ -2,6 +2,8 @@
 from django.shortcuts import render
 from django.conf import settings
 
+from functools import cache
+
 # This is the whole site navigation structure. Stick in a smarter file?
 sitenav = {
     'about': [
@@ -128,16 +130,23 @@ def _get_gitrev():
 # the current git revision. git revision is returned as a lazy object so
 # we don't spend effort trying to load it if we don't need it (though
 # all general pages will need it since it's used to render the css urls)
+#
+# Topbarnews needs to be available for the include topbar in cases when ESI
+# is not available. It is also evaluated lazily so on production website it
+# will only actually cause a query on the include page. PinnedNewsArticle has to
+# be imported here, to avoid recursive imports.
 def PGWebContextProcessor(request):
+    from pgweb.news.models import PinnedNewsArticle
+
     gitrev = SimpleLazyObject(_get_gitrev)
+    ctx = {
+        'gitrev': gitrev,
+        'do_esi': settings.DO_ESI,
+        'topbarnews': cache(lambda: PinnedNewsArticle.objects.select_related('pinnedarticle').only('pinnedarticle__id', 'pinnedarticle__date', 'pinnedarticle__title').first().pinnedarticle),
+    }
     if request.is_secure():
-        return {
+        return ctx | {
             'link_root': settings.SITE_ROOT,
-            'do_esi': settings.DO_ESI,
-            'gitrev': gitrev,
         }
     else:
-        return {
-            'gitrev': gitrev,
-            'do_esi': settings.DO_ESI,
-        }
+        return ctx

templates/pages/include/topbar.html

@@ -1,3 +1 @@
-June 4, 2026: <a href="/about/news/postgresql-19-beta-1-released-3313/">
-  PostgreSQL 19 Beta 1 Released!
-</a>
+{% if topbarnews %}{{ topbarnews.date | date:"F j, Y" }}: <a href="{{ topbarnews.permanenturl }}">{{ topbarnews.title }}</a>{% endif %}