Fixes streaming demo

Gemfile.lock

@@ -68,8 +68,8 @@ GEM
       pry (>= 0.13.0)
       shellany (~> 0.0)
       thor (>= 0.18.1)
-    guard-bundler (2.2.1)
-      bundler (>= 1.3.0, < 3)
+    guard-bundler (3.0.0)
+      bundler (>= 2.1, < 3)
       guard (~> 2.2)
       guard-compat (~> 1.1)
     guard-compat (1.2.1)
@@ -90,7 +90,6 @@ GEM
       mime-types-data (~> 3.2015)
     mime-types-data (3.2022.0105)
     mini_mime (1.1.2)
-    mini_portile2 (2.8.0)
     minitest (5.16.0)
     multi_json (1.15.0)
     mustermann (1.1.1)
@@ -99,8 +98,7 @@ GEM
       mustermann (>= 1.0.0)
     nenv (0.3.0)
     newrelic_rpm (8.8.0)
-    nokogiri (1.13.6)
-      mini_portile2 (~> 2.8.0)
+    nokogiri (1.13.6-x86_64-darwin)
       racc (~> 1.4)
     notiffany (0.1.3)
       nenv (~> 0.1)
@@ -153,7 +151,7 @@ GEM
       parser (>= 3.1.1.0)
     rubocop-rake (0.6.0)
       rubocop (~> 1.0)
-    rubocop-rspec (2.9.0)
+    rubocop-rspec (2.11.1)
       rubocop (~> 1.19)
     ruby-progressbar (1.11.0)
     ruby2_keywords (0.0.5)
@@ -174,7 +172,7 @@ GEM
     zeitwerk (2.6.0)
 
 PLATFORMS
-  ruby
+  x86_64-darwin-19
 
 DEPENDENCIES
   capybara
@@ -202,4 +200,4 @@ RUBY VERSION
    ruby 2.6.5p114
 
 BUNDLED WITH
-   1.17.3
+   2.3.15

api/upload_big_file.rb

@@ -0,0 +1,30 @@
+module Acme
+  class UploadBigFile < Grape::API
+    content_type :png, 'image/png'
+
+    desc 'Upload and download a big file of any format using IO.'
+    post 'big_download' do
+      filename = params[:file][:filename]
+      # content_type MIME::Types.type_for(filename)[0].to_s
+      content_type 'image/png'
+      env['api.format'] = :png
+      header 'Content-Disposition', "attachment; filename*=UTF-8''#{URI.escape(filename)}"
+
+      temp_file = params[:file][:tempfile]
+      stream FileStreamer.new temp_file.path
+      nil
+    end
+  end
+
+  class FileStreamer
+    def initialize(file_path)
+      @file_path = file_path
+    end
+
+    def each(&blk)
+      File.open(@file_path, 'r') do |file|
+        file.each(10, &blk)
+      end
+    end
+  end
+end

app/api.rb

@@ -12,6 +12,7 @@ class API < Grape::API
     mount ::Acme::GetJson
     mount ::Acme::ContentType
     mount ::Acme::UploadFile
+    mount ::Acme::UploadBigFile
     mount ::Acme::Entities::API
     mount ::Acme::Headers
     add_swagger_documentation api_version: 'v1'

spec/api/upload_big_file_spec.rb

@@ -0,0 +1,20 @@
+require 'spec_helper'
+
+describe Acme::API do
+  include Rack::Test::Methods
+
+  def app
+    Acme::API
+  end
+
+  it 'uploads and downloads a PNG file' do
+    image_filename = 'spec/fixtures/grape_logo.png'
+    post '/api/big_download.png', file: Rack::Test::UploadedFile.new(image_filename, 'image/png', true)
+    expect(last_response.status).to eq(201)
+    expect(last_response.headers['Content-Type']).to eq('image/png')
+    expect(last_response.headers['Content-Disposition']).to eq("attachment; filename*=UTF-8''grape_logo.png")
+    data = File.read(image_filename, encoding: 'UTF-8')
+    expect(last_response.body.encoding).to eq data.encoding
+    expect(last_response.body).to eq data
+  end
+end