Fixed a bug causing KeyError when saving with the parameter update_fields in which there are untracked fields.

AUTHORS.rst

@@ -19,3 +19,4 @@ Simon Meers <simon@simonmeers.com>
 sayane
 Trey Hunner <trey@treyhunner.com>
 zyegfryed
+Mikhail Silonov <silonov.pro>

CHANGES.rst

@@ -7,6 +7,9 @@ master (unreleased)
 * `Choices` now `__contains__` its Python identifier values. Thanks Keryn
   Knight. (Merge of GH-69).
 
+* Fixed a bug causing ``KeyError`` when saving with the parameter
+  ``update_fields`` in which there are untracked fields.
+
 
 1.4.0 (2013.06.03)
 ------------------

model_utils/tests/tests.py

@@ -923,6 +923,16 @@ class FieldTrackedModelCustomTests(FieldTrackerTestCase,
         self.instance.save()
         self.assertCurrent(name='new age')
 
+    def test_update_fields(self):
+        # Django 1.4 doesn't have update_fields
+        if django.VERSION >= (1, 5, 0):
+            self.update_instance(name='retro', number=4)
+            self.assertChanged()
+            self.instance.name = 'new age'
+            self.instance.number = 8
+            self.instance.save(update_fields=['name', 'number'])
+            self.assertChanged()
+
 
 class FieldTrackedModelAttributeTests(FieldTrackerTestCase):
 
@@ -976,7 +986,7 @@ class FieldTrackedModelAttributeTests(FieldTrackerTestCase):
 
 
 class FieldTrackedModelMultiTests(FieldTrackerTestCase,
-                                   FieldTrackerCommonTests):
+                                  FieldTrackerCommonTests):
 
     tracked_class = TrackedMultiple
 

model_utils/tracker.py

@@ -68,7 +68,8 @@ class FieldTracker(object):
 
     def finalize_class(self, sender, **kwargs):
         if self.fields is None:
-            self.fields = [field.attname for field in sender._meta.local_fields]
+            self.fields = (field.attname for field in sender._meta.local_fields)
+        self.fields = set(self.fields)
         self.field_map = self.get_field_map(sender)
         models.signals.post_init.connect(self.initialize_tracker, sender=sender)
         setattr(sender, self.name, self)
@@ -83,8 +84,19 @@ class FieldTracker(object):
         original_save = instance.save
         def save(**kwargs):
             ret = original_save(**kwargs)
+            update_fields = kwargs.get('update_fields')
+            if not update_fields and update_fields is not None:  # () or []
+                fields = update_fields
+            elif update_fields is None:
+                fields = None
+            else:
+                fields = (
+                    field for field in update_fields if
+                    field in self.fields
+                )
             getattr(instance, self.attname).set_saved_fields(
-                fields=kwargs.get('update_fields'))
+                fields=fields
+            )
             return ret
         instance.save = save