title: Mongoose, MongoDB: How to save() document after push()?
body: <p>Schema:</p>
  
  <pre><code>var Post = mongoose.Schema({
          title:       String,
          comments:    [{user: Number, text: String}]
      });
  </code></pre>
  
  <p>Code:</p>
  
  <pre><code>oldCount = myPost.comments.length;    // for example 'n'
  myPost.comments.push({user: 42, text: 'blablabla'});
  newCount = myPost.comments.length;    // should be 'n+1'
  myPost.save(function (err) {
      ...
    });
  </code></pre>
  
  <p>Is it a suitable code?</p>
  
  <p>Whether the <code>save()</code> will be executed after <code>push()</code>?</p>
  
  <p>Will I get the correct <code>newCount</code>?</p>