show announcements on main page

src/c3nav/site/models.py

@@ -1,4 +1,5 @@
 from django.conf import settings
+from django.core.cache import cache
 from django.db import models
 from django.db.models import Q
 from django.utils import timezone
@@ -22,8 +23,23 @@ class Announcement(models.Model):
 
     @classmethod
     def get_current(cls):
+        result = cache.get('site:announcement', None)
+        if result is not None:
+            return result
+
         try:
-            return cls.objects.filter(Q(active=True) & (Q(active_until__isnull=True) |
+            result = cls.objects.filter(Q(active=True) & (Q(active_until__isnull=True) |
                                                           Q(active_until__gt=timezone.now()))).latest()
         except cls.DoesNotExist:
-            return None
+            result = None
+
+        timeout = 300
+        if result.active_until:
+            timeout = max(0, min(timeout, (result.active_until-timezone.now()).total_seconds()))
+        cache.set('site:announcement', result, timeout)
+
+        return result
+
+    def save(self, *args, **kwargs):
+        super().save(*args, **kwargs)
+        cache.delete('site:announcement')

src/c3nav/site/views.py

@@ -25,6 +25,7 @@ from c3nav.mapdata.models.locations import LocationRedirect, SpecificLocation
 from c3nav.mapdata.utils.locations import get_location_by_slug_for_request, levels_by_short_label_for_request
 from c3nav.mapdata.utils.user import get_user_data
 from c3nav.mapdata.views import set_tile_access_cookie
+from c3nav.site.models import Announcement
 
 
 def check_location(location: Optional[str], request) -> Optional[SpecificLocation]:
@@ -89,6 +90,11 @@ def map_index(request, mode=None, slug=None, slug2=None, details=None,
         'tile_cache_server': settings.TILE_CACHE_SERVER,
         'embed': bool(embed),
     }
+
+    announcement = Announcement.get_current()
+    if announcement:
+        messages.info(request, announcement.text)
+
     response = render(request, 'site/map.html', ctx)
     set_tile_access_cookie(request, response)
     if embed: