Make change reason customizable with overriding.

AUTHORS.rst

@@ -15,6 +15,7 @@ Authors
 - Aleksey Kladov
 - Alexander Anikeev
 - Amanda Ng (`AmandaCLNg <https://github.com/AmandaCLNg>`_)
+- Amartis Gladius (`Amartis <https://github.com/amartis>`_)
 - Ben Lawson (`blawson <https://github.com/blawson>`_)
 - Benjamin Mampaey (`bmampaey <https://github.com/bmampaey>`_)
 - `bradford281 <https://github.com/bradford281>`_

CHANGES.rst

@@ -31,6 +31,7 @@ Full list of changes:
 - Fix bug with ``history.diff_against`` with non-editable fields (gh-923)
 - Dropped support for Django 3.1 (gh-952)
 - RecordModels now support a ``no_db_index`` setting, to drop indices in historical models, default stays the same (gh-720)
+- Support change reason formula feature. Change reason formula can be defined by overriding ``get_change_reason_for_object`` method after subclassing ``HistoricalRecords``
 
 3.0.0 (2021-04-16)
 ------------------

simple_history/models.py

@@ -541,11 +541,20 @@ def post_delete(self, instance, using=None, **kwargs):
         else:
             self.create_historical_record(instance, "-", using=using)
 
+    def get_change_reason_for_object(self, instance, history_type, using):
+        """
+        Get change reason for object.
+        Customize this method to automatically fill change reason from context.
+        """
+        return get_change_reason_from_object(instance)
+
     def create_historical_record(self, instance, history_type, using=None):
         using = using if self.use_base_model_db else None
         history_date = getattr(instance, "_history_date", timezone.now())
         history_user = self.get_history_user(instance)
-        history_change_reason = get_change_reason_from_object(instance)
+        history_change_reason = self.get_change_reason_for_object(
+            instance, history_type, using
+        )
         manager = getattr(instance, self.manager_name)
 
         attrs = {}