MongoDB bulk insert from mongoose models

gistfile1.js

var mongoose = require('mongoose');

var hitSchema = mongoose.Schema({
  text: String,
  music: String
});
hitSchema.statics.bulkInsert = function(models, fn) {
  if (!models || !models.length)
    return fn(null);

  var bulk = this.collection.initializeOrderedBulkOp();
  if (!bulk)
    return fn('bulkInsertModels: MongoDb connection is not yet established');

  var model;
  for (var i=0; i<models.length; i++) {
    model = models[i];
    bulk.insert(model.toJSON());
  }

  bulk.execute(fn);
};
var HitModel = mongoose.model('Hit', hitSchema);

mongoose.connect();
mongoose.connection.on("open", function(err, conn) {

  var model, models = [];
  for (var i=0; i<4; i++) {
    model = new HitModel();
    model.text = 'lalalalala';
    model.music = 'tou dou dou dou';
    models.push(model);
  }
  
  HitModel.bulkInsert(models, function(err, results) {
    if (err) {
      console.log(err);
      process.exit(1);
    } else {
      console.log(results);
      process.exit(0);
    }
  });
});