Respect the to_field setting and the target field type

Author: arski

simple_history/models.py

@@ -144,6 +144,8 @@ def copy_fields(self, model):
                     FieldType = type(old_field)
                 if django.get_version() >= "1.6":
                     field_arguments['db_constraint'] = False
+                if getattr(old_field, 'to_fields', []):
+                    field_arguments['to_field'] = old_field.to_fields[0]
                 field = FieldType(
                     old_field.rel.to,
                     related_name='+',

simple_history/tests/models.py

@@ -250,3 +250,12 @@ class UserAccessorOverride(models.Model):
 class Employee(models.Model):
     manager = models.OneToOneField('Employee', null=True)
     history = HistoricalRecords()
+
+
+class Country(models.Model):
+    code = models.CharField(max_length=15, unique=True)
+
+
+class Province(models.Model):
+    country = models.ForeignKey(Country, to_field='code')
+    history = HistoricalRecords()

simple_history/tests/tests/test_models.py

@@ -18,7 +18,7 @@
     AbstractBase, ConcreteAttr, ConcreteUtil, SelfFK, Temperature, WaterLevel,
     ExternalModel1, ExternalModel3, UnicodeVerboseName, HistoricalChoice,
     HistoricalState, HistoricalCustomFKError, Series, SeriesWork, PollInfo,
-    UserAccessorDefault, UserAccessorOverride, Employee
+    UserAccessorDefault, UserAccessorOverride, Employee, Country, Province
 )
 from ..external.models import ExternalModel2, ExternalModel4
 
@@ -257,6 +257,15 @@ def test_self_referential_foreign_key(self):
         self.assertEqual([m.fk_id for m in model.history.all()],
                          [other.id, model.id, None])
 
+    def test_to_field_foreign_key_save(self):
+        country = Country.objects.create(code='US')
+        country2 = Country.objects.create(code='CA')
+        province = Province.objects.create(country=country)
+        province.country = country2
+        province.save()
+        self.assertEqual([c.country_id for c in province.history.all()],
+                         [country2.code, country.code])
+
     def test_raw_save(self):
         document = Document()
         document.save_base(raw=True)