title: Mongo order by length of array
body: <p>Lets say I have mongo documents like this:</p>
  
  <p><strong>Question 1</strong></p>
  
  <pre><code>{
      answers:[
         {content: 'answer1'},
         {content: '2nd answer'}
      ]
  }
  </code></pre>
  
  <p><strong>Question 2</strong></p>
  
  <pre><code>{
      answers:[
         {content: 'answer1'},
         {content: '2nd answer'}
         {content: 'The third answer'}
      ]
  }
  </code></pre>
  
  <p>Is there a way to order the collection by size of answers? </p>
  
  <p>After a little research I saw suggestions of adding another field, that would contain number of answers and use it as a reference but may be there is native way to do it?</p>