Check for case-insensitive duplicates when creating new tags

AUTHORS

@@ -14,3 +14,4 @@ idle sign <idlesign@yandex.ru>
 Charles Leifer
 Florian Apolloner <apollo13@apolloner.eu>
 Andrew Pryde <andrew@rocketpod.co.uk>
+John Whitlock <jwhitlock@mozilla.com>

taggit/managers.py

@@ -197,36 +197,39 @@ def _to_tag_model_instances(self, tags):
                     "Cannot add {0} ({1}). Expected {2} or str.".format(
                         t, type(t), type(self.through.tag_model())))
 
-        if getattr(settings, 'TAGGIT_CASE_INSENSITIVE', False):
+        case_insensitive = getattr(settings, 'TAGGIT_CASE_INSENSITIVE', False)
+        manager = self.through.tag_model()._default_manager.using(db)
+
+        if case_insensitive:
             # Some databases can do case-insensitive comparison with IN, which
             # would be faster, but we can't rely on it or easily detect it.
             existing = []
             tags_to_create = []
 
             for name in str_tags:
                 try:
-                    tag = (self.through.tag_model()._default_manager
-                           .using(db)
-                           .get(name__iexact=name))
+                    tag = manager.get(name__iexact=name)
                     existing.append(tag)
                 except self.through.tag_model().DoesNotExist:
                     tags_to_create.append(name)
         else:
             # If str_tags has 0 elements Django actually optimizes that to not
             # do a query.  Malcolm is very smart.
-            existing = (self.through.tag_model()._default_manager
-                        .using(db)
-                        .filter(name__in=str_tags))
-
+            existing = manager.filter(name__in=str_tags)
             tags_to_create = str_tags - set(t.name for t in existing)
 
         tag_objs.update(existing)
 
         for new_tag in tags_to_create:
-            tag_objs.add(
-                self.through.tag_model()._default_manager
-                .using(db)
-                .create(name=new_tag))
+            if case_insensitive:
+                try:
+                    tag = manager.get(name__iexact=name)
+                except self.through.tag_model().DoesNotExist:
+                    tag = manager.create(name=new_tag)
+            else:
+                tag = manager.create(name=new_tag)
+
+            tag_objs.add(tag)
 
         return tag_objs
 

tests/tests.py

@@ -668,6 +668,13 @@ def test_with_case_insensitive_option(self):
         orange.tags.add('spain')
         self.assertEqual(list(orange.tags.all()), [spain])
 
+    @override_settings(TAGGIT_CASE_INSENSITIVE=True)
+    def test_with_case_insensitive_option_and_creation(self):
+        orange = self.food_model.objects.create(name="orange")
+        orange.tags.add('spain', 'Spain')
+        tag_names = list(orange.tags.names())
+        self.assertEqual(len(tag_names), 1, tag_names)
+
 
 class TaggableManagerDirectTestCase(TaggableManagerTestCase):
     food_model = DirectFood