file_upload_example.rb

require 'httparty'
require 'httmultiparty'

access_token = ""
domain = ""
course_id = ""
assignment_id = ""
file_path = ''
api_endpoint = "#{domain}/api/v1/courses/#{course_id}/assignments/#{assignment_id}/submissions/self/files"
file = File.new(file_path)
filename = File.basename(file_path)
filesize = file.size

headers = {"Authorization" => "Bearer #{access_token}"}

# Provision upload
options = {
    headers: headers,
    query: {name: filename, size: filesize}
}
response = HTTParty.post(api_endpoint, options)

if response.code != 200
  puts 'Provision Failed with #{response.code}'
  response
else
  response_parsed = JSON.parse(response.body)
  upload_params = response_parsed['upload_params'].merge('file' => file, 'Filename' => filename)
  upload_url = response_parsed['upload_url']
  # Perform upload
  options = {query: upload_params, :detect_mime_type => true, no_follow: true}
  begin
    HTTMultiParty.post(upload_url, options)
  rescue HTTParty::RedirectionTooDeep  #HTTPParty Doesn't handle redirects on file uploads, so just catch the exception
    response = HTTParty.post(upload_params['success_action_redirect'], {headers: headers})
    puts response.code
  end
end