title: Rails paper clip search file name
body: <p>I have a requirement for users to be able to search file names uploaded by paperclip. Looking at an uploaded document looks like this...</p>
  
  <pre><code>2.0.0-p353 :002 &gt; d=Document.last
    Document Load (0.4ms)  SELECT  "documents".* FROM "documents"   ORDER BY "documents"."id" DESC LIMIT 1
   =&gt; #&lt;Document id: 5, name: "hampton_george_27_70", transcription: "Asheville Nov 8th 1853 received of James A. Patton...", created_at: "2014-08-22 16:10:19", updated_at: "2014-08-22 16:37:51", document_file_name: "hampton_george_27_70.jpeg", document_content_type: "image/jpeg", document_file_size: 519652, document_updated_at: "2014-08-22 16:10:19"&gt; 
  2.0.0-p353 :003 &gt; d.document_file_name
   =&gt; "hampton_george_27_70.jpeg" 
  </code></pre>
  
  <p>But these are no traditional rails type models, so how would I go about searching them?</p>