brotherton-erpnext/erpnext/patches/v13_0/set_training_event_attendance.py

from __future__ import unicode_literals

import frappe


def execute():
    frappe.reload_doc('hr', 'doctype', 'training_event')
    frappe.reload_doc('hr', 'doctype', 'training_event_employee')

    frappe.db.sql("update `tabTraining Event Employee` set `attendance` = 'Present'")
    frappe.db.sql("update `tabTraining Event Employee` set `is_mandatory` = 1 where `attendance` = 'Mandatory'")