Rails 导出大容量 csv

def export_action
  respond_to do |format|  
    format.csv do
      filename = "large_file.csv"

      headers.delete("Content-Length")
      headers["Cache-Control"] = "no-cache"
      headers["Content-Type"] = "text/csv"
      headers["Content-Disposition"] = "attachment; filename=\"#{filename}\""
      headers["X-Accel-Buffering"] = "no"

      self.response_body = export_csv

      response.status = 200
    end
  end
end

def export_csv
  Enumerator.new do |yielder|
    # header: your csv header
    yielder << CSV.generate_line(header)

    # iterate your data to export
    limit = 5000
    pages = (total_count.to_i / limit.to_f).ceil

    pages.times do |offset_idx|
      Model.limit(limit).offset(offset_idx * limit).each do |row_result|
        yielder << CSV.generate_line(cvs_report_row(row_result))
      end
    end
  end
end
      
# format your csv row
def csv_report_row(row_result)
  csv_row = []
  csv_row << row_result.column
  csv_row
end