def _clone_surveys(self, new_event):
survey_attrs = get_simple_column_attrs(Survey) - {'uuid', 'start_dt', 'end_dt', '_last_friendly_submission_id'}
for old_survey in self.old_event.surveys:
if old_survey.is_deleted:
continue
survey = Survey()
survey.populate_from_attrs(old_survey, survey_attrs)
item_map = {}
for old_item in old_survey.items:
item = self._clone_item(survey, old_item)
if old_item.parent:
assert old_item.parent != old_item
try:
item.parent = item_map[old_item.parent]
except KeyError:
item.parent = item_map[old_item.parent] = self._clone_item(survey, old_item.parent)
item_map[old_item] = item
new_event.surveys.append(survey)
