old_contents: from django.db.models.fields.related import ForeignKey
  
  from .forms import AssetField
  
  
  class AssetKey(ForeignKey):
  
      def formfield(self, **kwargs):
          kwargs['form_class'] = AssetField
          return super(AssetKey, self).formfield(**kwargs)
  
      def value_from_object(self, obj):
          asset_obj = getattr(obj, self.name, None)
          if not asset_obj:
              return None
          return [asset_obj.id, asset_obj._meta.module_name]
  
  
  from south.modelsinspector import add_introspection_rules
  add_introspection_rules([], ["^fancypages\.assets\.fields\.AssetKey"])
  
new_contents: # -*- coding: utf-8 -*-
  from __future__ import unicode_literals, absolute_import
  import django
  from django.db.models.fields.related import ForeignKey
  
  from .forms import AssetField
  
  
  class AssetKey(ForeignKey):
  
      def formfield(self, **kwargs):
          kwargs['form_class'] = AssetField
          return super(AssetKey, self).formfield(**kwargs)
  
      def value_from_object(self, obj):
          asset_obj = getattr(obj, self.name, None)
          if not asset_obj:
              return None
          return [asset_obj.id, asset_obj._meta.module_name]
  
  
  # This is only required for Django version < 1.7 suing South for migrations
  if django.VERSION[:2] < (1, 7):
      from south.modelsinspector import add_introspection_rules
      add_introspection_rules([], ["^fancypages\.assets\.fields\.AssetKey"])
  
subject: Fix south introspection rule for custom AssetField