Ensure feed GUIDs are unchanging and unique

Implement 'tag:' style URIs for the GUID field on our RSS feeds. This
ensures new package updates show up as new, and we aren't jumping back
and forth between generated GUIDs having 'http://' and 'https://'
prefixes.

Much of the work here is to attempt to keep old news GUIDs constant so
we don't once again make everything show up as new in newsreaders.

Signed-off-by: Dan McGee <dan@archlinux.org>

1 files changed, 20 insertions, 4 deletions

diff --git a/news/models.py b/news/models.py
index c2d644b..c4fb136 100644
--- a/news/models.py
+++ b/news/models.py
@@ -1,13 +1,16 @@
+from datetime import datetime
+
 from django.db import models
 from django.contrib.auth.models import User
+from django.contrib.sites.models import Site
 
 class News(models.Model):
     slug = models.SlugField(max_length=255, unique=True)
     author = models.ForeignKey(User, related_name='news_author')
-    postdate = models.DateTimeField("post date", auto_now_add=True, db_index=True)
-    last_modified = models.DateTimeField(editable=False,
-            auto_now=True, db_index=True)
+    postdate = models.DateTimeField("post date", db_index=True)
+    last_modified = models.DateTimeField(editable=False, db_index=True)
     title = models.CharField(max_length=255)
+    guid = models.CharField(max_length=255, editable=False)
     content = models.TextField()
 
     def get_absolute_url(self):
@@ -22,10 +25,23 @@ class News(models.Model):
         get_latest_by = 'postdate'
         ordering = ['-postdate']
 
+def set_news_fields(sender, **kwargs):
+    news = kwargs['instance']
+    now = datetime.now()
+    news.last_modified = now
+    if not news.postdate:
+        news.postdate = now
+        # http://diveintomark.org/archives/2004/05/28/howto-atom-id
+        news.guid = 'tag:%s,%s:%s' % (Site.objects.get_current(),
+                now.strftime('%Y-%m-%d'), news.get_absolute_url())
+
 # connect signals needed to keep cache in line with reality
 from main.utils import refresh_news_latest
-from django.db.models.signals import post_save
+from django.db.models.signals import pre_save, post_save
+
 post_save.connect(refresh_news_latest, sender=News,
         dispatch_uid="news.models")
+pre_save.connect(set_news_fields, sender=News,
+        dispatch_uid="news.models")
 
 # vim: set ts=4 sw=4 et: