无法从结果集中获取行

以下函数将数据保存在cassandra. 它调用abstract rowToModel在同一个类中定义的方法将返回的数据cassandra转换为相应的数据模型。

def saveDataToDatabase(data:M):Option[M] = { //TODOM - should this also be part of the Repository trait?
    println("inserting in table "+tablename+" with partition key  "+partitionKeyColumns +" and values "+data)
    val insertQuery = insertValues(tablename,data)
    println("insert query is "+insertQuery)
    try {
      val resultSet:ResultSet = session.execute(insertQuery) //execute can take a Statement. Insert is derived from Statement so I can use Insert.
      println("resultset after insert: " + resultSet)
      println("resultset applied: " + resultSet.wasApplied())
      println(s"columns definition ${resultSet.getColumnDefinitions}")
      if(resultSet.wasApplied()){
        println(s"saved row ${resultSet.one()}")
        val savedData = rowToModel(resultSet.one())
        Some(savedData)
      } else {
        None
      }
    }catch {
      case e:Exception => {
        println("cassandra exception "+e)
        None
      }
    }
  }

的abstract rowToModel定义如下

override def rowToModel(row: Row): PracticeQuestionTag = {
   PracticeQuestionTag(row.getLong("year"),row.getLong("month"),row.getLong("creation_time_hour"),
      row.getLong("creation_time_minute"),row.getUUID("question_id"),row.getString("question_description"))

  }

但是我在其中定义的打印语句saveDataToDatabase没有打印数据。我原以为打印件会打印出来，PracticeQuestionTag但我看到的是以下内容

我希望看到这样的东西 -PracticeQuestionTag(2018,6,1,1,11111111-1111-1111-1111-111111111111,some description1)当我one从 ResultSet`打印时。但我看到的是

resultset after insert: ResultSet[ exhausted: false, Columns[[applied](boolean)]] resultset applied: true columns definition Columns[[applied](boolean)] saved row Row[true] row to Model called for row null cassandra exception java.lang.NullPointerException

为什么ResultSet，one并且columnDefinitions没有显示数据模型中的值？