title: chewy searching only by id
body: <p>I'm using <a href="https://github.com/toptal/chewy" rel="nofollow">chewy</a>.</p>
  
  <p>I can't find 'ops' using any fields of op, except id.</p>
  
  <p><strong>Model:</strong></p>
  
  <pre><code>class Op
    include Mongoid::Document
    ...
    state_machine :initial =&gt; :draft do
    ...
    end
    update_index 'ops#op', :self
  end
  </code></pre>
  
  <p><strong>Index:</strong></p>
  
  <pre><code>class OpsIndex &lt; Chewy::Index
    define_type Op
  end
  </code></pre>
  
  <p><strong>Controller:</strong></p>
  
  <pre><code>def index
    OpsIndex.reset! # =&gt; true
    OpsIndex.purge  # =&gt; {\"acknowledged\"=&gt;true}
    OpsIndex::Op.import # =&gt; true
  
    scope = OpsIndex::Op.query term: { _id: '55263b48336f63004a000000' }
    scope.total_count # =&gt; 1 nice!
    scope.to_a.inspect =&gt; #&lt;OpsIndex::Op:0x00000006f5f310 @attributes={\"_id\"=&gt;{\"$oid\"=&gt;\"55263b48336f63004a000000\"}, \"state\"=&gt;\"deactivated\" ...
  
    #But
    scope = OpsIndex::Op.query term: { state: 'deactivated' }
    scope.total_count # =&gt; 0
  end
  </code></pre>
  
  <p><strong>In development.log:</strong></p>
  
  <pre><code>[1m[32mOpsIndex::Op Search (7.4ms)[0m {:body=&gt;{:query=&gt;{:term=&gt;{:_id=&gt;"55263b48336f63004a000000"}}}, :index=&gt;["development_ops"], :type=&gt;["op"]}
  [1m[32mOpsIndex::Op Search (3.2ms)[0m {:body=&gt;{:query=&gt;{:term=&gt;{:state=&gt;"deactivated"}}}, :index=&gt;["development_ops"], :type=&gt;["op"]}
  </code></pre>
  
  <p><strong>What's wrong?</strong></p>