def date_parse(datetime_str)
      start_str, end_str = datetime_str.split(' - ')
      date_str = start_str.split(' ')[0]
      end_str = "#{date_str} #{end_str}"
      self.start_datetime = DateTime.parse(start_str + " JST")
      self.end_datetime = DateTime.parse(end_str + " JST")
    end
def date_parse(datetime_str)
      start_str, end_str = datetime_str.split(' - ')
      date_str = start_str.split(' ')[0]
      end_str = "#{date_str} #{end_str}"
      self.start_datetime = DateTime.parse(start_str + " JST")
      self.end_datetime = DateTime.parse(end_str + " JST")
    end
2012-12-01 14:00 - 18:00 のような形式を処理する