为什么我的CSV会在每行后写一个标题？

Question

我有一个名为info的数组，我想将每行添加到CSV中，但我还想将标题包含在文件的顶部。

我这样做了：

  info.each do |listing|
    CSV.open(csvfile, "a+", write_headers: true, headers: ["Company_Name","Website","Street_Address", "City", "State", "Zip", "Phone","Email"]) do |csv|
      csv << listing
    end
  end

但这会产生如下情况：

这不是我想要的。

我只想在顶部有一个标题行。

我如何实现这一目标？

修改1

我实际上有另一个具有相同问题的嵌套循环，但我不能简单地将其移出循环 - 那么我怎么能解决这个问题呢？

  csvs.each do |csv|
    CSV.foreach(csv, headers: true) do |row|
      #check for presence of valid email
      if (!row['Email'].nil?) && (!row['Email'].include? "no email")
        CSV.open(new_csv, "a+", write_headers: true, headers: ["Company_Name","Website","Street_Address", "City", "State", "Zip", "Phone","Email"]) do |new_csv_row|
          new_csv_row << row
          puts "#{row['Email']} successfully added to #{new_csv}"
        end
      end
    end
  end

Answer 1

对于第一个更改循环：

CSV.open(csvfile, "a+", write_headers: true, headers: ["Company_Name","Website","Street_Address", "City", "State", "Zip", "Phone","Email"]) do |csv|
  info.each do |listing|
    csv << listing
  end
end

第二个：

header_written = {} # memorize if header is allready written
csvs.each do |csv|
  ...
  # alternative can be 'write_headers: !File.exist?(new_csv)'
  # but this works only when this file is created here and no empty file exists
  CSV.open(new_csv, "a+", write_headers: !header_written[new_csv], headers: ["Company_Name","Website","Street_Address", "City", "State", "Zip", "Phone","Email"]) do |new_csv_row|
          new_csv_row << row
          puts "#{row['Email']} successfully added to #{new_csv}"
  end
  header_written[new_csv] ||= true

编辑：我刚刚认识到new_csv不是动态的。因此，您可以将第二个CSV.open调用放在循环外部或使用简单标记而不是header_written[]，以便将其更改为header_written = false|true。