content: from django.db import migrations
  import mptt
  import mptt.managers
  
  
  def rebuild_mptt(apps, schema_editor):
      manager = mptt.managers.TreeManager()
      ModuleBay = apps.get_model('dcim', 'ModuleBay')
      manager.model = ModuleBay
      mptt.register(ModuleBay)
      manager.contribute_to_class(ModuleBay, 'objects')
      manager.rebuild()
  
  
  class Migration(migrations.Migration):
      dependencies = [
          ('dcim', '0190_nested_modules'),
      ]
  
      operations = [
          migrations.RunPython(code=rebuild_mptt, reverse_code=migrations.RunPython.noop),
      ]
  