File Upload

Canvas File Upload Example

Canvas File Upload Example

canvas_file_upload.rb

require 'faraday'
require 'faraday_middleware'
class CanvasFileUpload

  attr_reader :access_token, :url, :file_path

  def initialize(access_token:, url:)
    @access_token = access_token
    @url = url
    @file_path = file_path
  end

  def upload_file(file_path)
    params = declare_file(file_params(file_path))
    confirm_url = post_file(params['upload_url'], params['upload_params'], file_path)
    confirm_file_upload(confirm_url)
  end

  private
  
  def declare_file(params)
    response = canvas_connection.post(url, params)
    raise 'DeclareFileFailedException' unless response.success?
    response.body
  end

  def post_file(url, params, file_path)
    puts params
    params['Filename'] = File.basename(file_path)
    params['file'] = Faraday::UploadIO.new(file_path, params['content-type'])
    response = upload_connection.post(url, params)
    if [302, 303].include? response.status #success if it is a redirect
      response.headers['Location']
    else
      raise 'FailedFileUpload'
    end
  end

  def confirm_file_upload(url)
    uri = URI(url)
    response = canvas_connection.post(url)
    raise 'ConfirmFileFailedException' unless response.success?
    response.body
  end

  def canvas_connection
    @conn ||= Faraday.new do |faraday|
      faraday.request  :multipart             # form-encode POST params
      faraday.request  :url_encoded
      faraday.response :logger                  # log requests to STDOUT
      faraday.adapter  Faraday.default_adapter  # make requests with Net::HTTP
      faraday.authorization :Bearer, @access_token
      faraday.response :json, :content_type => /\bjson$/
    end
  end

  def base_url
    @domain ||= URI.join(url, '/').to_s
  end


  def file_params(file_path)
    {
        size: File.open(file_path).size,
        name: File.basename(file_path)
    }
  end

  def upload_connection
    Faraday.new do |f|
      f.request :multipart
      f.request :url_encoded
      f.adapter :net_http
    end
  end

end

canvs_file_upload_spec.rb

require_relative 'canvas_file_upload'
require 'webmock/rspec'

RSpec.describe CanvasFileUpload do
  subject {CanvasFileUpload.new(access_token: 'token', url: 'http://uploader')}

  it 'uploads a file to canvas' do
    stub_request(:post, "http://uploader").
        with(:body => {"name"=>"canvas_file_upload_spec.rb", "size"=>/.*/},
             :headers => {'Authorization'=>'Bearer token', 'Content-Type'=>'application/x-www-form-urlencoded'}).
        to_return(:status => 200,
                  :body => {upload_url: 'http://uploader-frd', upload_params: {a:'hi',b:'so neat'}}.to_json,
                  headers: {'Content-Type' => 'application/json'})

    stub_request(:post, "http://uploader-frd/").
        with(:headers => {'Content-Type'=>/multipart\/form-data/}).
        to_return(:status => 302, :body => "", :headers => {'Location' => 'http://confirm-url'})

    stub_request(:post, "http://confirm-url/").
        with(:headers => {'Authorization'=>'Bearer token'}).
        to_return(:status => 200, :body => "", :headers => {})

    subject.upload_file(__FILE__)
  end
end

Gemfile

source 'https://rubygems.org'

gem 'faraday'
gem 'faraday_middleware'
gem 'rspec'
gem 'webmock'

Gemfile.lock

GEM
  remote: https://rubygems.org/
  specs:
    addressable (2.4.0)
    crack (0.4.3)
      safe_yaml (~> 1.0.0)
    diff-lcs (1.2.5)
    faraday (0.9.1)
      multipart-post (>= 1.2, < 3)
    faraday_middleware (0.9.1)
      faraday (>= 0.7.4, < 0.10)
    hashdiff (0.3.0)
    multipart-post (2.0.0)
    rspec (3.2.0)
      rspec-core (~> 3.2.0)
      rspec-expectations (~> 3.2.0)
      rspec-mocks (~> 3.2.0)
    rspec-core (3.2.3)
      rspec-support (~> 3.2.0)
    rspec-expectations (3.2.1)
      diff-lcs (>= 1.2.0, < 2.0)
      rspec-support (~> 3.2.0)
    rspec-mocks (3.2.1)
      diff-lcs (>= 1.2.0, < 2.0)
      rspec-support (~> 3.2.0)
    rspec-support (3.2.2)
    safe_yaml (1.0.4)
    webmock (1.24.2)
      addressable (>= 2.3.6)
      crack (>= 0.3.2)
      hashdiff

PLATFORMS
  ruby

DEPENDENCIES
  faraday
  faraday_middleware
  rspec
  webmock

BUNDLED WITH
   1.11.2