title: How to use field value as key name in Mongodb result
body: <p>Can somebody tell me please if is possible to use field value as key in mongodb result. If I have documents like</p>
  <pre><code>{'code': 'xxx', 'item': 'yyy'}
  {'code': 'ooo', 'item': 'eee'}
  </code></pre>
  <p>I would like to get result where code value will be the key like</p>
  <pre><code>{'xxx': 'yyy'}, {'ooo': 'eee'}
  </code></pre>