download, unzip and process on memory with Ruby

main.rb

# HTTP 上の zip ファイルをオンメモリで DL/加工 した結果をファイルに保存.
# 行単位での読み出し/加工/書き出しを意識した実装.

if __FILE__ == $0
  url = "http://localhost:8000/1020201008_00.csv.zip"

  require "open-uri"
  require "zip"
  File.open('conved.csv', 'w') do |output|
    OpenURI.open_uri(url) do |payload_io|
      Zip::InputStream.open(payload_io) do |zip_io|
        zip_io.get_next_entry

        zip_io.gets # abandon first line (header)

        while line = zip_io.gets
          output.puts line.split(',').values_at(0, 4, 5, 7).join(',')
        end
      end
    end

    # require "net/http"
    # require "uri"
    # uri = URI.parse(url)
    # Net::HTTP.start(uri.host, uri.port) do |http|
    #   # FIXME: IO インターフェイスなオブジェクトで payload を取りたい
    #   response = http.get(uri.path)
    #
    #   Zip::File.open_buffer(response.body) do |zipfile|
    #     entry = zipfile.first
    #     io = entry.get_input_stream
    #
    #     io.gets # abandon first line (header)
    #
    #     while line = io.gets
    #       output.puts line.split(',').values_at(0, 4, 5, 7).join(',')
    #     end
    #   end
    # end
  end
end