lpr-partynest/app/views/application/_navbar.html.erb

<nav class="navbar navbar-expand-lg navbar-dark bg-dark">
  <a class="navbar-brand" href="<%= root_path %>">
    <%= translate :title %>
  </a>

  <button class="navbar-toggler"
          type="button"
          data-toggle="collapse"
          data-target="#navbarSupportedContent"
          aria-controls="navbarSupportedContent"
          aria-expanded="false"
          aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>

  <div class="collapse navbar-collapse" id="navbarSupportedContent">
    <% if user_signed_in? %>
      <ul class="navbar-nav ml-auto">
        <li class="nav-item dropdown">
          <%= link_to truncate(current_user.email),
                      '#',
                      id: :navbarDropdown,
                      role: :button,
                      class: 'nav-link dropdown-toggle',
                      'data-toggle': :dropdown,
                      'aria-haspopup': true,
                      'aria-expanded': false %>

          <div class="dropdown-menu" aria-labelledby="navbarDropdown">
            <%= link_to translate('users.shared.links.settings'),
                        edit_user_registration_path,
                        role: :button,
                        class: 'dropdown-item' %>

            <div class="dropdown-divider"></div>
            <%= link_to translate('users.shared.links.sign_out'),
                        destroy_user_session_path,
                        method: :delete,
                        role: :button,
                        class: 'dropdown-item' %>
          </div>
        </li>
      </ul>
    <% else %>
      <div class="ml-auto">
        <%= link_to translate('users.shared.links.sign_in'),
                    new_user_session_path,
                    role: :button,
                    class: 'btn btn-light mr-2' %>

        <%= link_to translate('users.shared.links.sign_up'),
                    new_user_registration_path,
                    role: :button,
                    class: 'btn btn-primary' %>
      </div>
    <% end %>
  </div>
</nav>