school-platform/app/views/layouts/_navigation.html.erb

<nav class="navbar navbar-default navbar-static-top" role="navigation" style="margin-bottom: 0">
  <div class="navbar-header">
    <button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".navbar-collapse">
      <span class="sr-only">Toggle navigation</span>
      <span class="icon-bar"></span>
      <span class="icon-bar"></span>
      <span class="icon-bar"></span>
    </button>
    <%= link_to "School Platform", root_path, class: "navbar-brand" %>
  </div>

  <ul class="nav navbar-top-links navbar-right">
    <li class="dropdown">
      <a class="dropdown-toggle" data-toggle="dropdown" href="#">
        <%= fa_icon "envelope fw" %>
        <% count = unread_messages_count current_user %>
          <% if count > 0 %>
            (<span class="unread-messages"><%= count %></span>)
          <% end %>
          <%= fa_icon "caret-down" %>
        </a>
        <ul class="dropdown-menu dropdown-messages">
          <% for conversation in current_user.conversations.sort_by{ |conversation| conversation.messages.last.created_at }[0..1] %>
            <% message = conversation.messages.last %>
              <li>
                <%= link_to "#{conversation_path conversation}#message-#{message.id}" do %>
                <div>
                  <span class="pull-right text-muted">
                    <em><%= time_ago_in_words(message.created_at) %>
                      ago</em>
                  </span>
                  <strong><%= message.user.name %></strong>

                </div>
                <div><%= truncate(message.content, length: 100) %></div>
              <% end %>
            </li>
            <li class="divider"></li>
          <% end %>
          <li>
            <%= link_to conversations_path, class: 'text-center' do %>
            <strong>Read All Messages</strong>
            <%= fa_icon("angle-right") %>
          <% end %>
        </li>
      </ul>
    </li>
    <li class="dropdown">
      <a class="dropdown-toggle" data-toggle="dropdown" href="#">
        <%= fa_icon "user fw" %><%= fa_icon "caret-down" %>
      </a>
      <ul class="dropdown-menu dropdown-user">
        <li>
          <%= link_to fa_icon("user fw", text: "User Profile"), current_user %>
        </li>
        <li>
          <%= link_to fa_icon("gear fw", text: "Settings"), edit_user_path(current_user) %>
        </li>
        <li class="divider"></li>
        <li>
          <%= link_to fa_icon("sign-out fw", text: "Logout"), logout_path, method: :delete %>
        </li>
      </ul>
    </li>
  </ul>

  <div class="navbar-default sidebar" role="navigation">
    <div class="sidebar-nav navbar-collapse">
      <ul class="nav" id="side-menu">
        <li class="sidebar-search">
          <div class="input-group custom-search-form">
            <input type="text" class="form-control" placeholder="Search...">
            <span class="input-group-btn">
              <button class="btn btn-default" type="button">
                <i class="fa fa-search"></i>
              </button>
            </span>
          </div>
        </li>
        <li>
          <%= link_to fa_icon("home fw", text: "Home"), home_path %>
        </li>
        <li>
          <%= link_to fa_icon("envelope fw", text: "Conversations"), conversations_path %>
        </li>
        <% for school in (current_user.schools_administering + [current_user.school]).uniq.compact do %>
          <li>
            <%= link_to fa_icon("building fw", text: school.name), school_path(school) %>
          </li>
        <% end %>
        <li>
          <%= link_to fa_icon("book fw", text: "Courses"), courses_user_path(current_user) %>
        </li>
        <li>
          <%= link_to fa_icon("paperclip fw", text: "Assignments"), assignments_path %>
        </li>
      </ul>
    </div>
  </div>
</nav>