title: How to exclude some fields from the document
body: <p>I have the following simple shema:</p>
  
  <pre><code> var userSchema = new Schema({
      name : String,
     age: Number,
     _creator: Schema.ObjectId
    });
  
    var User = mongoose.model('User',userSchema);
  </code></pre>
  
  <p>What I want to do is create the new document and return to client, but I want to exclude the 'creator' field from one:</p>
  
  <pre><code>app.post('/example.json', function (req, res) {
     var user = new User({name: 'John', age: 45, _creator: 'some ObjectId'});
     user.save(function (err) {
        if (err) throw err;
  
        res.json(200, {user: user});     // how to exclude the _creator field?
     });
  });
  </code></pre>
  
  <p>At the end I want to send the new created user without _creator field:</p>
  
  <pre><code>{
     name: 'John',
     age: 45
  } 
  </code></pre>
  
  <p>Is it possible to make without extra find request to mongoose? </p>
  
  <p><strong>P.S</strong>:It's preferable to make it by </p>