mongoose: emit update or create

something.js

var mongoose = require('mongoose');
var Schema = mongoose.Schema;
mongoose.connect('localhost', 'testing_emitUpdate');

var schema = new Schema({
    name: String
});

schema.pre('save', function (next) {
  this._wasNew = this.isNew;
  next();
});

schema.post('save', function () {
  if (this._wasNew) console.error('new!');
  else console.error('updated!');
});

var A = mongoose.model('A', schema);

mongoose.connection.on('open', function () {
  var a = new A({ name: 'emitUpdate' });
  a.save(function (err, a) {
    if (err) return console.error(err.stack||err);

    A.findById(a, function (err, doc) {
      if (err) console.error(err.stack||err);

      doc.name = 'aasdf';
      doc.save(function (err) {
        mongoose.connection.db.dropDatabase(function () {
          mongoose.connection.close();
        });
      });

    });
  })
});