announce status computing methods

corbo/models.py

@@ -26,6 +26,19 @@ class Announce(models.Model):
         return u'{title} ({id}) at {mtime}'.format(title=self.title,
                                     id=self.id, mtime=self.mtime)
 
+    def is_published(self):
+        if self.publication_time:
+            if self.expiration_time:
+                return self.publication_time <= timezone.now() < self.expiration_time
+            return self.publication_time <= timezone.now()
+
+    def is_expired(self):
+        if self.expiration_time:
+            return self.expiration_time > timezone.now()
+
+    def is_not_published(self):
+        return not self.publication_time
+
     class Meta:
         verbose_name = _('announce')
         ordering = ('-mtime',)