Ruby on Rails - OAuth 2 multipart Post (Uploading to Facebook or Soundcloud)

Question

I am working on a Rails App that Uses OmniAuth to gather Oauth/OAuth2 credentials for my users and then posts out to those services on their behalf.

Creating simple posts to update status feeds work great.. Now I am to the point of needing to upload files. Facebook says "To publish a photo, issue a POST request with the photo file attachment as multipart/form-data." http://developers.facebook.com/docs/reference/api/photo/

So that is what I am trying to do:

I have implemented the module here: Ruby: How to post a file via HTTP as multipart/form-data? to get the headers and data...

if appearance.post.post_attachment_content_type.to_s.include?('image')

  fbpost = "https://graph.facebook.com/me/photos"

  data, headers = Multipart::Post.prepare_query("title" => appearance.post.post_attachment_file_name  , "document" => File.read(appearance.post.post_attachment.path))

  paramsarray = {:source=>data, :message=> appearance.post.content}
  response = access_token.request(:post, fbpost, paramsarray, headers)
  appearance.result = response
  appearance.save
end

I but I am getting a OAuth2::HTTPError - HTTP 400 Error

Any assistance would be Incredible... As I see this information will also be needed for uploading files to SoundCloud also.

Thanks,

Mark

score 3 · Accepted Answer · answered Apr 28 '14 at 20:57

Struggled with this myself. The oauth2 library is backed by Faraday for it's HTTP interaction. with a little configuration it supports uploaded files out of the box. First step is to add the appropriate Faraday middleware when building your connection. An example from my code:

OAuth2::Client.new client_id, secret, site: site do |stack|
  stack.request :multipart
  stack.request :url_encoded
  stack.adapter  Faraday.default_adapter
end

This adds the multipart encoding support to the Faraday connection. Next when making the request on your access token object you want to use a Faraday::UploadIO object. So:

upload = Faraday::UploadIO.new io, mime_type, filename
access_token.post('some/url', params: {url: 'params'}, body: {file: upload})

In the above code:

io - An IO object for the file you want to upload. Can be a File object or even a StringIO.

mime_type - The mime type of the file you are uploading. You can either try to detect this server-side or if a user uploaded the file to you, you should be able to extract the mime type from their request.

filename - What are are calling the file you are uploading. This can also be determined by your own choosing or you can just use whatever the user uploading the file calls it.

some/url - Replace this with the URL you want to post to

{url: 'params'} - Replace this with any URL params you want to provide

{file: upload} - Replace this with your multipart form data. Obviously one (or more) of the key/value pairs should have an instance of your file upload.

score 0 · Answer 2 · answered Apr 29 '13 at 06:28

I'm actually using successfully this code to upload a photo on a fb page :

dir = Dir.pwd.concat("/public/system/posts/images")
fb_url = URI.parse("https://graph.facebook.com/#{@page_id}/photos")
img = File.open("myfile.jpg")
req = Net::HTTP::Post::Multipart.new(
  "#{fb_url.path}?access_token=#{@token}", 
  "source" => UploadIO.new(img, "application/jpg", img.path),
  "message" => "some messsage"
) 
n = Net::HTTP.new(fb_url.host, fb_url.port)
n.use_ssl = true
n.verify_mode = OpenSSL::SSL::VERIFY_NONE
n.start do |http|
  @result = http.request(req)
end

Ruby on Rails - OAuth 2 multipart Post (Uploading to Facebook or Soundcloud)

2 Answers2