title: Mongo update while excluding certain fields
body: <p>This sounds like it would be similar to a Mongo $set. In this case, I would like to update the document (update and/or delete fields) but ignore the field creatorName, keeping it the same.</p>
  
  <p>Example document:</p>
  
  <pre><code>{id: 1, firstName: 'Testy', middleName: 'Jim', lastName: 'Shorts', creatorName: 'User1'}
  </code></pre>
  
  <p>Updated to:</p>
  
  <pre><code>{id: 1, firstName: 'Production', lastName: 'Pants', creatorName: 'User1'}
  </code></pre>
  
  <p>If I use set, creatorName remains the same (good) and firstName and lastName are updated (good), but middleName is not deleted (bad). Set limits the ability to remove a field during an update.</p>
  
  <p>Can this be done in a query? Without $unset?</p>