title: undefined local variable or method `current_user'
body: <p>I am building my first Ruby on Rails app (ruby 2.0.0p353) by following the <a href="http://teamtreehouse.com/library/build-a-simple-ruby-on-rails-application" rel="nofollow">teamtreehouse.com guide</a>. </p>
  
  <p>I am using devise 3.2.2 <a href="https://github.com/plataformatec/devise" rel="nofollow">devise</a> and in application.html.erb I want to use devise's "current_user" in order to display the name of the logged in user.</p>
  
  <p>Here the code where I am using "current_user":</p>
  
  <pre><code>    &lt;ul class="nav navbar-nav pull-right"&gt;
        &lt;li&gt;&lt;%= link_to current_user.first_name, "#" %&gt;&lt;/li&gt; 
        &lt;li&gt;&lt;%= link_to "Log Out", destroy_user_session_path, method: :delete %&gt;&lt;/li&gt; 
      &lt;/ul&gt;
  </code></pre>
  
  <p>routes.db:</p>
  
  <pre><code>Treebook::Application.routes.draw do
     devise_for :t_busers
     resources :statuses
     root to: 'statuses#index'
  end
  </code></pre>
  
  <p>However when running my application I am always getting the following error:</p>
  
  <pre><code>undefined local variable or method `current_user' for #&lt;#&lt;Class:0x007f98b1d0edb8&gt;:0x007f98b1cff6d8&gt;
  </code></pre>
  
  <p>I am getting the same error with other methods of devise. I get the error no matter if I am signed in or not signed out. The sign-up, edit etc. of devise seems to work fine. I have tried putting "before_filter :authenticate_user!" into application_controller.rb as indicated in the documentation of devise but that doesn't work either.</p>
  
  <p>Is there anything I need to do in order to use the helpers of devise in a view?</p>