我正在尝试使用自定义方法在猫鼬的顶部开发一个类，因此我用自己的类扩展了猫鼬，但是当我调用创建一个新的car方法时，它可以工作，但是它的剥离和错误，在这里让你看看我要做什么。

我收到此警告

(node:3341) DeprecationWarning: Mongoose: mpromise (mongoose's default promise library) is deprecated, plug in your own promise library instead: http://mongoosejs.com/docs/promises.html

我做完之后

driver.createCar({
      carName: 'jeep',
      availableSeats: 4,
    }, callback);

driver是Driver类的实例

const carSchema = new Schema({
  carName: String,
  availableSeats: Number,
  createdOn: { type: Date, default: Date.now },
});
const driverSchema = new Schema({
 email: String,
 name: String,
 city: String,
 phoneNumber: String,
 cars: [carSchema],
 userId: {
   type: Schema.Types.ObjectId,
   required: true,
 },
createdOn: { type: Date, default: Date.now },
});
const DriverModel = mongoose.model('Driver', driverSchema);

class Driver extends DriverModel {
  getCurrentDate() {
  return moment().format();
}
create(cb) {
  // save driver
  this.createdOn = this.getCurrentDate();
  this.save(cb);
}
remove(cb) {
  super.remove({
  _id: this._id,
 }, cb);
}
createCar(carData, cb) {
  this.cars.push(carData);
  this.save(cb);
}
getCars() {
  return this.cars;
 }
}

关于我在做什么错的任何想法？