0016_project.py

    def forwards(self, orm):
        project_ct = orm['contenttypes.ContentType'].objects.get(app_label="pekama", model="project")
        with orm.Folder.objects.disable_mptt_updates():
            def assign_folder(project):
                if project is None:
                    return project
                try:
                    f = orm.Folder.objects.get(content_type=project.content_type, object_id=project.object_id)
                    f.content_type = project_ct
                    f.object_id = project.pk
                    f.parent = assign_folder(project.parent)
                    return f
                except orm.Folder.DoesNotExist:
                    orm.Folder.objects.create(content_type=project_ct, object_id=project.pk, is_object_root=True, is_system=True, parent=assign_folder(project.parent))
            for p in orm['pekama.Project'].objects.all():
                assign_folder(p)
        orm.Folder.objects.rebuild()