如何将python的“none”类型转换为“null”类型

如何将python的“none”类型转换为“null”类型?我正在使用python vertica模块查询vertica数据库,并将结果集写入csv文件,其中python csv模块将null插入为none。因此,当我将这个csv文件导入到vetica数据库时,我得到的空字符串为',其中我希望它为空。我猜这里的问题是因为python没有类型。我该怎么解决?

以下是将数据导出到CSV的代码:

def get_data(table, startDate, endDate, config):
  connFrom = vertica_connect_from(config)
  cursor = connFrom.cursor()

  if startDate == endDate:
      command = "select * from dev.{} where report_date='{}'".format(table,startDate)
  else:
      command = "select * from dev.{} where report_date between '{}' and '{}'".format(table, startDate, endDate)

  cursor.execute(command)
  rows = cursor.fetchall()

  with open(filePath, 'w') as csvfile:
      writer = csv.writer(csvfile, delimiter="|")
      for row in rows:
          for index, item in enumerate(row):
              if (item == 0.0):
                  row[index] = 0
          writer.writerow(row)
      logger.info('Data has been copied and written to CSV file at %s', filePath)

  connFrom.close()

下面是我导入它的方法:

def load_data(table, config):
  connTo = vertica_connect_to(config)
  cur = connTo.cursor()

  importCommand = "copy qa.{} from stdin null as '' rejected data '{}' exceptions '{}'".format(table,rejectedLog, exceptionLog)
  with open(filePath, 'r') as fil:
      try:
          cur.copy(importCommand, fil)
      except Exception as e:
          logger.error('%s', e)
      logger.info('Data has been copied, check rejected/exception files at /tmp on the destination host for any errors')

  connTo.close()