[extensions-web] extensions: Use the latest() method on QuerySet, not our own arithmetic

[Jasper St. Pierre <jstpierre src gnome org>]

commit bdc6bbdb9e0ed7131502e2f0a73c014675a078f7
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Fri Mar 2 22:16:33 2012 -0500

    extensions: Use the latest() method on QuerySet, not our own arithmetic

 sweettooth/extensions/models.py |   23 +++++++++++------------
 1 files changed, 11 insertions(+), 12 deletions(-)
---
diff --git a/sweettooth/extensions/models.py b/sweettooth/extensions/models.py
index 8b9d842..72ec02b 100644
--- a/sweettooth/extensions/models.py
+++ b/sweettooth/extensions/models.py
@@ -105,10 +105,10 @@ class Extension(models.Model):
 
     @property
     def latest_version(self):
-        qs = self.visible_versions.order_by("-version")
-        if qs.exists():
-            return qs[0]
-        return None
+        try:
+            return self.visible_versions.latest()
+        except ExtensionVersion.DoesNotExist:
+            return None
 
     def user_can_edit(self, user):
         if user == self.creator:
@@ -282,6 +282,7 @@ class ExtensionVersion(models.Model):
 
     class Meta:
         unique_together = ('extension', 'version'),
+        get_latest_by = 'version'
 
     def __unicode__(self):
         return "Version %d of %s" % (self.version, self.extension)
@@ -355,15 +356,13 @@ class ExtensionVersion(models.Model):
     def save(self, *args, **kwargs):
         assert self.extension is not None
 
-        # get version number
-        ver_ids = self.extension.versions.order_by('-version')
+        # Get version number
         try:
-            ver_id = ver_ids[0].version + 1
-        except IndexError:
-            # New extension, no versions yet
-            ver_id = 1
-
-        self.version = ver_id
+            # Don't use extension.latest_version, as that will
+            # give us the latest visible version.
+            self.version = self.extension.versions.latest().version + 1
+        except self.DoesNotExist:
+            self.version = 1
 
         super(ExtensionVersion, self).save(*args, **kwargs)