gistfile1.rb

## sessions_controller.rb ##
 def new
    @title = "Add session"

    archive = Archive::Directory.new(Rails.root.join("spec/fixtures/archive"))
    @new_files = files_in_archive_not_in_db(archive)
  end

  private

    def files_in_archive_not_in_db(archive)
      new_files = {}

      archive.sessions.each do |archive_session|
        if Session.where(:session_date => Date.strptime(archive_session,
                                               "%Y.%m.%d").to_date)
          archive.files_in_session(archive_session).each do |archive_file|
            unless Song.where(:file_name => archive_file)
              new_files[archive_session] = []
              new_files[archive_session].push(archive_file)
            end
          end
        end
      end

      return new_files
    end


## _new.html.erb ##

<h3>Add a new session</h3>
<% @new_files.each do |sess, files| %>
  <p><%= sess %></p>
  <ul>
    <% files.each do |file| %>
      <li id="<%= sess + file %>"><%= file %></li>
    <% end %>
  </ul>
<% end %>