Elixir Phoenix Framework: Add class to active navigation entry

app.html.eex

...
<div class="container">
  <%= render "top_navi.html", conn: @conn %>
</div>
...

layout_view.ex

defmodule MyApp.LayoutView do
  use MyApp.Web, :view
  import MyApp.PageHelper
end

page_helper.ex

defmodule MyApp.PageHelper do
  use MyApp.Web, :controller

  def page_path?(conn, method) do
    current_path = Path.join(["/" | conn.path_info])
    cond do
      page_path(conn, method) == current_path -> true
      true -> false
    end
  end
end

top_navi.html.eex

...
<ul class="nav navbar-nav">
  <li class="nav-item<%= if page_path?(@conn, :index) do %> active<% end %>">
    <%= link "Listing", to: page_path(@conn, :index), class: "nav-link" %>
  </li>
  <li class="nav-item<%= if page_path?(@conn, :stats) do %> active<% end %>">
    <%= link "Statistics", to: page_path(@conn, :stats), class: "nav-link" %>
  </li>
</ul>
...