title: reshape result from mongodb
body: <p>In my node.js app I use a mongodb with the mongoose driver. How can I reshape the result from the Modell.find() operation? If I got and example document like this:</p>
  
  <pre><code>{
     _id:   ObjectId(...),
     score: 14,
     time:  123
  }
  </code></pre>
  
  <p>and in my find operation I want to ad a index (counter) on the results from .find() and rename the _id field. Is this possible?</p>
  
  <p>If want my document stream to look something like this:</p>
  
  <pre><code>[{
     index:   0
     player:  ObjectId // _id field renamed to player
     score:   14,
     time:    123
  },
  {
     index:   1
     player:  ObjectId // _id field renamed to player
     score:   6,
     time:    321
  },
  ...
  {
     index:   N
     player:  ObjectId // _id field renamed to player
     score:   1,
     time:    456
  }
  ]
  </code></pre>
  
  <p>I tried with</p>
  
  <pre><code>Modell.find({}, {player: '$_id', score: 1, time: 1})
        .exec(function(err, players) {
           ...
  });
  </code></pre>
  
  <p>But the _id field is not renamed in the resulting document stream. Is this possible? And how do I create a counter of the documents in the document stream.</p>