title: Why root route not working with users#show?
body: <p>I tried this as my root route <code>root 'users#show'</code> so that the User is taken to his profile upon logging in, but instead I'm confronted with this error:</p>
  
  <pre><code>ActiveRecord::RecordNotFound in UsersController#show
  Couldn't find User with 'id'= 
  @user = User.find(params[:id])
  </code></pre>
  
  <p>When I use profile as its own tab via, <code>&lt;li&gt;&lt;%= link_to "Profile", current_user %&gt;&lt;/li&gt;</code> this works, but I can't put <code>root 'current_user'</code> or I get this error:</p>
  
  <pre><code>ArgumentError
  Missing :action key on routes definition, please check your routes.
  root 'current_user'
  </code></pre>
  
  <p>Thank you for your time.</p>