Javascript 如何更新mongoose模式中的字段以及模式中数组中的新推送？

我的应用程序中有两个

模式。详情如下:

培训师单一评级模式：

  trainerID: String,
  userID: String,
  rating: Number,
  review: String,
  addedOn: String,
};
const TrainerSingleRating = mongoose.model(
  "TrainerSingleRating",
  trainerSingleRating
);```


  trainerID: String,
  averageRating: Number,
  ratings: [trainerSingleRating],
};
const TrainerRatings = mongoose.model("TrainerRatings", trainerRatings);```



培训师评分模式：

  trainerID: String,
  userID: String,
  rating: Number,
  review: String,
  addedOn: String,
};
const TrainerSingleRating = mongoose.model(
  "TrainerSingleRating",
  trainerSingleRating
);```


  trainerID: String,
  averageRating: Number,
  ratings: [trainerSingleRating],
};
const TrainerRatings = mongoose.model("TrainerRatings", trainerRatings);```



我正在使用一个函数更新和创建数据库中的文档。
下面是我的函数代码：

function saveTrainerRatings(trainerID, userID, ratings, review) {
  const date = moment().format("DD MMM YYYY");
  const trainerSingleRating = new TrainerSingleRating({
    trainerID: trainerID,
    userID: userID,
    rating: ratings,
    review: review,
    addedOn: date,
  });

  TrainerRatings.findOne({ trainerID: trainerID }, function (
    err,
    foundRatingList
  ) {
    const oldAverageRating = foundRatingList.averageRating;
    const newAverageRating = (oldAverageRating + parseInt(ratings)) / 2;
    const trainerRatings = new TrainerRatings({
      trainerID: trainerID,
      averageRating: ratings,
      ratings: [trainerSingleRating],
    });
    if (err) {
      console.log(err);
    } else {
      if (!foundRatingList) {
        trainerRatings.save();
      } else {
        const oldAverageRating = foundRatingList.averageRating;
        foundRatingList.ratings.push(trainerSingleRating);
        foundRatingList.averageRating.update(newAverageRating);
        foundRatingList.save();
      }
    }
  });
  trainerSingleRating.save();
}

因此，每次用户给培训师评分时，都会创建并保存新文档，并将其推送到
trainer rating
模式中的评分数组中

我需要根据所有评分计算平均评分。目前，我正试图通过在每次创建新文档时更新平均评级来解决此问题。但问题是，我收到一个错误，说
foundRatingList.averageRating.update不是一个函数

如何解决此错误？或者是否有任何解决方法将新文档推送到
评级数组
，同时更新
平均值

谢谢你的建议