Display menu items based on role-based access control

menu_helper.rb

# Given an app with Role-based access control (for example cancan)
module MenuHelper

  def menu_item(*args)
    options = args.last.is_a?(Hash) ? args.pop : {}
    klass = args.pop
    return nil unless can?(:index, klass)
    args << klass.model_name.route_key
    path = "/#{args.join('/')}"
    content_tag(:li, class: ('active' if request.path.starts_with?(path))) do
      link_to(t(args.join('.'), scope: 'app.menu'), path, options)
    end
  end

end

x_en.yml

app:
  menu:
    admin:
      users: All users
    manager:
      users: My team

x_example.html.haml

%ul.menu
  %li= link_to(
  = menu_item(:admin, User, id: 'people')
  = menu_item(:manager, User, id: 'folks')

  -# Some exceptions may need to be made...
  - if current_user.persisted?
    %li= link_to 'Sign out', destroy_user_session_path, method: :delete
  - else
    %li= link_to "Sign in", new_user_session_path

-# Resulting in:
    <ul class='menu'>
      <li id='people'><a href='/admin/users'>All users</a></li>
      <li id='folks' class='active'><a href='/manager/users'>My team</a></li>
    </ul>

    <!-- etc... -->