title: How to get file extension when renaming file with cffile
body: <p>I'm using a <code>cffile</code> tag to upload my file and resave it with a new name. My issue is that the file could be a few different formats and I don't know how to detect the file extension. I'm using the code below:</p>
  
  <pre><code>&lt;cfset ui = createUUID()&gt;
  &lt;cffile 
    action="upload" 
    accept="video/x-flv, video/mp4, video/x-msvideo"
    destination="e:\www2\uploads\#ui#.#cffile.ServerFileExt#" 
    nameconflict="makeunique" 
    filefield="form.file"
  &gt;
  </code></pre>
  
  <p>It's telling me that cffile is undefined.</p>