我如何才能以功能性方式正确编写此代码而无需重复

Question

在以下函数中，我传递了一个Option。根据{{​​1}}是Option还是Some，我需要调用特定的API，但是其余的代码对于None和{{1 }}。我不知道如何删除代码重复。我该如何以函数式编程风格重新编写代码？

Some

Answer 1

def getRowsByPartitionKeyId(
  id:I, 
  pagingStateOption:Option[PagingState]
): (Option[List[M]], Option[PagingState]) = {

  val resultSet = session.execute(pagingStateOption match {
    case Some(pagingState: PagingState) => 
      whereClause.setFetchSize(1).setPagingState(pagingState)
    case None =>
      whereClause.setFetchSize(1)
  })

  val it = resultSet.iterator();//resultSet is an iterator
  val newPagingState:PagingState = resultSet.getExecutionInfo.getPagingState


  if (it.hasNext) {


    val resultSetAsList:List[Row] = asScalaIterator(it).toList
    val resultSetAsModelList = rowToModel(resultSetAsList.head)


    Tuple2(Some(List(resultSetAsModelList)),Some(pagingState))
  } else {
    Tuple2(None, None)
  }
}

Answer 2

知道了。我忘记了Scala中的所有内容都返回了一个值，甚至返回了match，所以我可以做到这一点

val resultSet = pagingStateOption match {
  case Some(pagingState: PagingState) => {
    println("got paging state:" +pagingState)
    session.execute(whereClause
      .setFetchSize(1)
      .setPagingState(pagingState)) //get one row from ResultSet. Cassandra might return more or less though
  }
  case None => {
    session.execute(whereClause
      .setFetchSize(1)) //get one row from ResultSet. Cassandra might return more or less though
  }
}