snippet.rb

class MyApp < Sinatra::Base
  
  # ....
  
  # does nothing other than load the <input type="file"> form...
  get '/upload' do
    erb(:upload)
  end
  
  post '/upload' do
    if params[:filedata] # NB!! this depends on the params value you send from the form
      # params.inspect
      filename = params[:filedata][:filename]
      file = params[:filedata][:tempfile]
      filepath = File.join(__PATH_TO_YOUR_ROOT, 'public', 'upload_dir', filename)
      
      err = File.open(filepath, 'wb') { |f| f.write(file.read) }
      # test if successfully uploaded (uses Kernel#test )
      return test(?f,filepath) ? "#{filename} <span>successfully uploaded.</span>" : "Upload Error: #{filename} failed due to = err=[#{err}]"
    else
      return "Upload Error: Wrong params sent. No file was uploaded. Please check your code."
    end
  end
  
  
  ## SAFARI 3 UPLOAD BUG FIX
  get '/safari-upload-fix' do
    headers "Connection" => 'close'
    ''
  end
  
end


###################################
# Add this to fix a really irritating Safari 3 bug (a few hours wasted on it :( )


### Then add this JS (using JQuery) on your upload page

%Q[/* HACK ALERT: Safari 3.x intermittently hangs when making uploads. 
 * The following code prevents that by doing a AJAX request to the server
 * immediately before the upload is submitted. The server returns an empty 
 * document with the "Connection: close" header, telling Safari to close the active connection. 
*/
 $('#{submit_btn}').click(function() { if ($.browser.safari) { $.ajax({ url: "/safari-upload-fix", async: false }); } });]


# That all works just fine