title: Problems with FriendlyId and parameters
body: <p>I am trying to change my urls from whatever.com/users/1 to whatever.com/users/jamie.Surname or whatever.com/users/jamie-Surname</p>
  
  <p>I would quite like to eventually change to whatever.com/jamie.surname or whatever.com/jamie-surname but I thought it would be best to start of simple.</p>
  
  <p>So I installed the friendly_id gem, starting simple I tried to just have it route to my first name with;</p>
  
  <pre><code>class User &lt; ActiveRecord::Base
        extend FriendlyId
        friendly_id :first_name
  </code></pre>
  
  <p><strong>However when I try to go to the url I am getting the error;</strong></p>
  
  <p>ActiveRecord::RecordNotFound in UsersController#show</p>
  
  <p>Couldn't find User without an ID</p>
  
  <p>Application Trace | Framework Trace | Full Trace
  app/controllers/users_controller.rb:22:in `show'</p>
  
  <p>Request
  Parameters:
  {"id"=>"jamie"}</p>
  
  <p><strong>This line is the method in my users_controller where its throwing up the error</strong></p>
  
  <pre><code>def show
      @user = User.find(params[:id])
          respond_to do |format|
          format.html 
          format.json { render json: @user }
      end
  end
  </code></pre>
  
  <p>I can't seem to figure out a way to fix this.</p>
  
  <p>Any help or suggestions/pushes in the right direction would be much appreciated.</p>