title: What is `stringify_keys' in rails and how to solve it when this error comes
body: <p>In a partial file of my application I have the following code snippet for displaying user navigation(through Devise):-</p>
  
  <pre><code>&lt;ul class="nav pull-right"&gt;
    &lt;% if user_signed_in? %&gt;
        &lt;li&gt;
          &lt;%= current_user.email do %&gt;
          &lt;i class=" icon-user icon-black"&gt;&lt;/i&gt;
          &lt;% end %&gt;
        &lt;/li&gt;
       &lt;li&gt;
         &lt;%= link_to "Your Links", profiles_index_path do %&gt;
         &lt;i class=" icon-user icon-black"&gt;&lt;/i&gt;
         &lt;% end %&gt;
       &lt;/li&gt; 
       &lt;li&gt;
         &lt;%= link_to "Sign out", destroy_user_session_path, :method =&gt; 'delete' do %&gt;
         &lt;i class=" icon-user icon-black"&gt;&lt;/i&gt; 
         &lt;% end %&gt;
      &lt;/li&gt;
  
     &lt;% else %&gt;
       &lt;li&gt;
        &lt;%= link_to "Login", new_user_session_path do %&gt; 
        &lt;i class=" icon-lock"&gt;&lt;/i&gt;  
        &lt;% end %&gt;
      &lt;/li&gt;
      &lt;li&gt;
        &lt;%= link_to "Sign up", new_user_registration_path do %&gt;
        &lt;i class=" icon-home"&gt;&lt;/i&gt;
        &lt;% end %&gt;
      &lt;/li&gt;
    &lt;% end %&gt;
  &lt;/ul&gt;
  </code></pre>
  
  <p>But I'm getting an error saying:-</p>
  
  <pre><code>undefined method `stringify_keys' for "/users/sign_in":String
  </code></pre>
  
  <p>Now my questions are:-</p>
  
  <ol>
  <li>What is <strong>`stringify_keys'</strong> in general??</li>
  <li>How do I resolve this in my code???</li>
  </ol>
  
  <p>Thanks...</p>