title: Can't find object when use Mongoid vs RoR
body: <p>Have some strange problem when use Mongoid</p>
  
  <p>I have the method in my controller:</p>
  
  <pre><code>def show
    @artist = Artist.find(params[:id])
    @albums = @artist.albums
  end
  </code></pre>
  
  <p>And when I debuggin it i have result:</p>
  
  <pre><code>(byebug) Artist.find(params[:id])
  MONGODB | localhost:27017 | test_taskv1_development.find | STARTED | {"find"=&gt;"artists", "filter"=&gt;{"_id"=&gt;BSON::ObjectId('574eea06ca418b3348657ea3')}}
  MONGODB | localhost:27017 | test_taskv1_development.find | SUCCEEDED | 0.007681416999999999s
  #&lt;Artist _id: 574eea06ca418b3348657ea3, name: "Muse", itunes_id: 1093360&gt;
  (byebug) @artist
  nil 
  </code></pre>
  
  <p>So, <code>Artist.find(params[:id])</code> have a value what I need, but @artist is nil.
  I do not understand how it happens. Maybe I missed something in mongoid documentation.
  Sorry for my english</p>