title: Automatic createdAt and updatedAt fields in Meteor
body: <p>In my collection I'd like to have automatically generated <code>createdAt</code> and <code>updatedAt</code> fields that would contain the date of when the object was inserted / updated for the last time - kind of like it's happening in Ruby on Rails. Currently I'm doing this with an observer similar to this one:</p>
  
  <pre><code>MyCollection.find({}).observeChanges({
    changed: function(id, changes) {
      MyCollection.update(id, ...);
    },
  });
  </code></pre>
  
  <p>Is there a better / more efficient / more straightforward way?</p>