def update_comments_in_parent_after_request():
	if hasattr(frappe.local, "_comments"):
		for (reference_doctype, reference_name, _comments) in frappe.local._comments:
			add_column(reference_doctype, "_comments", "Text")
			update_comments_in_parent(reference_doctype, reference_name, _comments)

		frappe.db.commit()
update _comments in parent if _comments column is missing
dataset/ETHPy150Open frappe/frappe/frappe/core/doctype/communication/comment.py/update_comments_in_parent_after_request