Fixed KeyError when cleaning duplicate history

...on models with `excluded_fields`.

Author: ddabble

CHANGES.rst

@@ -10,6 +10,7 @@ Unreleased
 - Add basic support for many-to-many fields (gh-399)
 - Added support for Django 4.1 (gh-1021)
 - Added ``tracked_fields`` attribute to historical models (gh-1038)
+- Fixed ``KeyError`` when running ``clean_duplicate_history`` on models with ``excluded_fields`` (gh-1038)
 
 3.1.1 (2022-04-23)
 ------------------

simple_history/models.py

@@ -928,9 +928,7 @@ def diff_against(self, old_history, excluded_fields=None, included_fields=None):
 
         included_m2m_fields = {field.name for field in old_history._history_m2m_fields}
         if included_fields is None:
-            included_fields = {
-                f.name for f in old_history.instance_type._meta.fields if f.editable
-            }
+            included_fields = {f.name for f in old_history.tracked_fields if f.editable}
         else:
             included_m2m_fields = included_m2m_fields.intersection(included_fields)
 

simple_history/tests/tests/test_commands.py

@@ -410,6 +410,25 @@ def test_auto_cleanup_with_excluded_fields(self):
         )
         self.assertEqual(Poll.history.all().count(), 1)
 
+    def test_auto_cleanup_for_model_with_excluded_fields(self):
+        p = PollWithExcludeFields.objects.create(
+            question="Will this be deleted?", pub_date=datetime.now()
+        )
+        self.assertEqual(PollWithExcludeFields.history.all().count(), 1)
+        p.pub_date = p.pub_date + timedelta(days=1)
+        p.save()
+        self.assertEqual(PollWithExcludeFields.history.all().count(), 2)
+        out = StringIO()
+        management.call_command(
+            self.command_name, auto=True, stdout=out, stderr=StringIO()
+        )
+        self.assertEqual(
+            out.getvalue(),
+            "Removed 1 historical records for "
+            "<class 'simple_history.tests.models.PollWithExcludeFields'>\n",
+        )
+        self.assertEqual(PollWithExcludeFields.history.all().count(), 1)
+
 
 class TestCleanOldHistory(TestCase):
     command_name = "clean_old_history"