When I download Excel files, strange files are stored

Question

I want to download uploaded files such as .zip, .xlsm, xlsx, pdf... ..., etc., that have been uploaded, I want to eventually compress them into a zip file for download.

However, if the uploaded files are not zipped, they will be downloaded with strange files stored in them.

In this case, .xlsm

Source Code

class DownloadZipsController < ::ApplicationController

      def index
        file_name = "#{Time.current.strftime("%Y%m%d_%H%M%S")}.zip"
        zip_file = Tempfile.new(file_name)

        Zip.unicode_names = true
        Zip::OutputStream.open(zip_file.path) do |zip|
          params[:product_ids].each do |product_id|
            product = Product.find(product_id)
            zip.put_next_entry("output.zip")
            zip.print Net::HTTP.get URI.parse(product.submit_zip_file.url)
          end
        end

        send_file zip_file.path,
              type: "application/zip",
              disposition: "attachment",
              filename: file_name

        zip_file.close

      rescue => e
        logger.debug e.backtrace
        redirect_to request.referer, alert: e.message
      end

    end

Uploaded files are stored in AWS S3.

Is there any solution to this problem?

Answer 1

Office Documents such as .xlsm, .xlsx, .docx, and others are in fact zip files containing the document as a xml file plus additional resources.

The file tree you have shown in your screenshot shows the content of one such document if you interpret it as a zip file and unpack.

It appears that somewhere in your code, you have detected the document file as a zip file and interpreted it as such which resulted in its contents to be unpacked.

This is not apparent from the code you have posted though, so I would assume that you have some additional handling of zip files somewhere else (such as a function to download existing files which may then be send with a wrong content type to the browser, i.e as an application/zip rather than application/vnd.ms-excel.sheet.macroEnabled.12).