title: access db.serverStatus() of mongo in mongoose @3.6.20
body: <p>I want to use db.serverStatus() using mongoose@3.6.20 </p>
  
  <p>I have already use this // its working in mongoose updated version which is 5.0 above</p>
  
  <p><a href="https://stackoverflow.com/questions/37831667/mongoose-db-stats-equivalent">mongoose-db-stats</a></p>
  
  <pre class="lang-js prettyprint-override"><code>mongoose.connect("mongodb://url");
  var db = mongoose.connection;
  db.on("error", console.error.bind(console, "connection error:"));
  db.on("open", function() {
    db.db.stats(function(err, stats) {
      console.log(stats);
      callback(stats);
    });
  });
  </code></pre>
  
  <p>something like this but from <code>db.on('open',function(){</code> this line is not working </p>
  
  <p>I am using node -v <code>7.10.0</code>
  monsoose -v <code>3.6.20</code></p>
  
  <p>If anything missing in question then please ask.</p>