title: How to List All Badges Except Those Badges Already Completed
body: <p>How can <code>@badges_available</code> list all badges from <code>User.first</code> (the admin user) except for those badges which have already been completed by current_user? Something like <code>.where(title != @badges_available.title)</code></p>
  
  <pre><code>@badges_available = User.first.badges.where.not(title: current_user.badges.title) # undefined method `title' for #&lt;Badge::ActiveRecord_Associations_CollectionProxy:0x007fb85a6db2c0&gt;
  @badges_completed = @user.badges
  </code></pre>
  
  <p>This way in the view the there is never a duplication of <code>title</code>. If an <code>available</code> badge is completed then it should only show under <code>completed</code> and not <code>available</code> anymore.</p>
  
  <pre><code>&lt;% @badges_completed.each do |completed| %&gt;
    &lt;%= completed.title %&gt;&lt;br&gt;
  &lt;% end %&gt;
  
  &lt;% @badges_available.each do |available| %&gt;
    &lt;%= available.title %&gt;
  &lt;% end %&gt;
  </code></pre>