Grape: Corrupted stream output for xlsx files

[wprater]

Hi,

Im using the axlsx gem to create an xlsx file. The generation of the file works fine, but when I try to stream from the Grape API, the file is corrupted. Both from either method:

axlsx_package.serialize('simple.xlsx')

# send the file directly as stream
return File.open('simple.xlsx')

# or stream from the gem
return axlsx_package.to_stream.read

Any ideas what is causing this? The grape API is mounted within a Rails app.

[dblock]

Define "corrupted". Are you returning the correct content-type? What data is being returned? Post a complete repro with a failing test.

[wprater]

Numbers.app says the following "Import Error" "An unknown error occurred."

Im setting a content-type of application/vnd.openxmlformats-officedocument.spreadsheetml.sheet

The data being returned is something like this:

["PK\u0003\u0004\u0014\u0000\u0000\u0000\b\u0000\u0000€Ÿëc8kÔÙ\u0000\u0000\u0000A\u0002\u0000\u0000\u000B\u0000\u0000\u0000_rels/.rels­’ÁNÃ0\f†ï<EäûšnH\b¡e» ¤Ý\u0010*\u000F`\u0012·ÚÄ‘\u0013 ¼=\u0003bh\b\u000E;ZöÿýßÁÛý\u0012fõB’=G\u0003ë¦\u0005EѲóq0ðØÝ­®a¿Û>ÐŒ¥^äѧ¬j$f\u0003c)éFëlG\n","˜\u001BN\u0014ë¦g\tXê(ƒNh'\u001CHoÚöJËw\u0006\u001C3U‡2P1°Ìú•ezbžš\n",

I cannot send the complete file, but what gets me is that the file being serialized to disk is OK, but streaming that same file causes an issue.

[dblock]

Write something that reproduces the problem based on https://github.com/dblock/grape-on-rack

[wprater]

Any ideas on this issue? Something more I can do to help?
I made a failing test branch on rack here:
https://github.com/wprater/grape-on-rack/tree/corrupt-axslx

[presskey]

In your example format specified as :json (app/api.rb:4), try to use :txt instead.

[dblock]

You need a proper content-type and either a pass-through or some more specific formatter. Like this:

require 'axlsx'

module Acme
  class AxlsxBuild < Grape::API
    content_type :xlsx, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
    format :xlsx
    formatter :xlsx, lambda { |object, env| object.to_stream.read }

    desc "Axlsx."
    get "axlsx" do
      header['Content-Disposition'] = "attachment; filename=report.xlsx"
      content_type 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'
      p = ::Axlsx::Package.new
      p.workbook.add_worksheet(:name => 'Test sheet') do |sheet|
        sheet.add_row ['Foobar test']
      end
      p.use_shared_strings = true
      p.serialize('simple.xlsx')
      p
    end
  end
end