'Actions after deleting a case event:
- update last_seen_on in the corresponding cases
@param row: the deleted Row'

@staticmethod
def case_event_ondelete(row):

    table = current.s3db.dvr_case_event
    row = current.db((table.id == row.id)).select(table.deleted_fk, limitby=(0, 1)).first()
    if (row and row.deleted_fk):
        try:
            deleted_fk = json.loads(row.deleted_fk)
        except (ValueError, TypeError):
            person_id = None
        else:
            person_id = deleted_fk.get('person_id')
        if person_id:
            dvr_update_last_seen(person_id)
