Patch CustomForeignKeyField.do_related_class method for migrations

Author: macro1

simple_history/models.py

@@ -301,7 +301,15 @@ def get_field(self, other, cls):
     def do_related_class(self, other, cls):
         field = self.get_field(other, cls)
         if not hasattr(self, 'related'):
-            self.related = RelatedObject(other, cls.instance_type, self)
+            try:
+                instance_type = cls.instance_type
+            except AttributeError:  # when model is reconstituted for migration
+                natural_key = "{app}.{model}".format(
+                    app=cls._meta.app_label,
+                    model=cls.__name__[10:],
+                )
+                instance_type = cls._meta.apps.get_model(natural_key)
+            self.related = RelatedObject(other, instance_type, self)
         transform_field(field)
         field.rel = None
 

simple_history/tests/tests/test_commands.py

@@ -1,6 +1,11 @@
 from contextlib import contextmanager
 from six.moves import cStringIO as StringIO
 from datetime import datetime
+try:
+    from unittest import skipUnless
+except ImportError:
+    from unittest2 import skipUnless
+import django
 from django.test import TestCase
 from django.core import management
 from simple_history import models as sh_models
@@ -101,3 +106,10 @@ def test_no_historical(self):
                                     stdout=out)
         self.assertIn(populate_history.Command.NO_REGISTERED_MODELS,
                       out.getvalue())
+
+
+class TestMigrate(TestCase):
+
+    @skipUnless(django.get_version() >= "1.7", "Requires 1.7 migrations")
+    def test_migrate_command(self):
+        management.call_command('migrate', fake=True, stdout=StringIO())