Wrong fix for missing tagline. SHould instead create a FeedData.

utils/feed_fetcher.py

@@ -14,7 +14,6 @@ import isodate
 import urlparse
 from django.conf import settings
 from django.db import IntegrityError
-from django.db.models.fields.related_descriptors import RelatedObjectDoesNotExist
 from django.core.cache import cache
 from apps.reader.models import UserSubscription
 from apps.rss_feeds.models import Feed, MStory
@@ -470,11 +469,7 @@ class ProcessFeed:
         if self.feed.feed_title != original_title:
             self.feed.save(update_fields=['feed_title'])
         
-        try:
-            tagline = self.fpf.feed.get('tagline', self.feed.data.feed_tagline)
-        except RelatedObjectDoesNotExist:
-            tagline = None
-
+        tagline = self.fpf.feed.get('tagline', self.feed.data.feed_tagline)
         if tagline:
             original_tagline = self.feed.data.feed_tagline
             self.feed.data.feed_tagline = smart_unicode(tagline)

utils/fields.py

@@ -1,14 +1,41 @@
+import django
 from django.db.models import OneToOneField
-from django.db.models.fields.related import ReverseOneToOneDescriptor
+from django.db.transaction import atomic
+try:
+    from django.db.models.fields.related_descriptors import (
+        ReverseOneToOneDescriptor,
+    )
+except ImportError:
+    from django.db.models.fields.related import SingleRelatedObjectDescriptor as ReverseOneToOneDescriptor
+
 
 
 class AutoSingleRelatedObjectDescriptor(ReverseOneToOneDescriptor):
+    """
+    The descriptor that handles the object creation for an AutoOneToOneField.
+    """
+
+    @atomic
     def __get__(self, instance, instance_type=None):
+        model = getattr(self.related, 'related_model', self.related.model)
+
         try:
-            return super(AutoSingleRelatedObjectDescriptor, self).__get__(instance, instance_type)
-        except self.related.model.DoesNotExist:
-            obj = self.related.model(**{self.related.field.name: instance})
-            obj.save()
+            return (
+                super(AutoSingleRelatedObjectDescriptor, self)
+                .__get__(instance, instance_type)
+            )
+        except model.DoesNotExist:
+            # Using get_or_create instead() of save() or create() as it better handles race conditions
+            obj, _ = model.objects.get_or_create(**{self.related.field.name: instance})
+
+            # Update Django's cache, otherwise first 2 calls to obj.relobj
+            # will return 2 different in-memory objects
+            if django.VERSION >= (2, 0):
+                self.related.set_cached_value(instance, obj)
+                self.related.field.set_cached_value(obj, instance)
+            else:
+                setattr(instance, self.cache_name, obj)
+                setattr(obj, self.related.field.get_cache_name(), instance)
             return obj
 
 
@@ -25,4 +52,4 @@ class AutoOneToOneField(OneToOneField):
             icq = models.IntegerField(max_length=255, null=True)
     '''
     def contribute_to_related_class(self, cls, related):
-        setattr(cls, related.get_accessor_name(), AutoSingleRelatedObjectDescriptor(related))
+        setattr(cls, related.get_accessor_name(), AutoSingleRelatedObjectDescriptor(related))