Rails export to csv multiple table in a same file

export_controller.rb

 def backup
    models = ["table1s","table2s","table3s"]
    all_data = Hash.new
    models.map do |model_name|
      table_data = []
      model_name = model_name.split("")
      model_name.pop
      model_name = model_name.join("")
      model_name.camelize.constantize.all.map do |data|
        table_data.push(data)
      end
      all_data[model_name.camelize] = table_data
    end
    send_data export_csv(all_data), filename: "Export - #{Date.today}.csv" and return
  end

  def export_csv(data)
    csvfile = CSV.generate(headers: true) do |csv|
      data.each do |key, value|
        csv << [key]
        attributes  = key.camelize.constantize.column_names
        csv << attributes
        value.each do |val|
          csv << val.attributes.values_at(*attributes)
        end
        csv << ['eot']
      end
    end
    return csvfile
  end