虚拟和填充不会在mongoose上显示

const mongoose = require('mongoose');

const commentSchema = new mongoose.Schema({
  text: String,
  user: { type: mongoose.Schema.Types.ObjectId, ref: 'User' }
});

const articleSchema = new mongoose.Schema({
  title: String,
  content: String,
  comments: [{ type: mongoose.Schema.Types.ObjectId, ref: 'Comment' }]
});

// 定义虚拟属性，计算文章评论数
articleSchema.virtual('commentCount').get(function() {
  return this.comments.length;
});

const Comment = mongoose.model('Comment', commentSchema);
const Article = mongoose.model('Article', articleSchema);

// 获取文章列表，并填充评论数据
Article.find().populate('comments').exec((err, articles) => {
  if (err) {
    console.error(err);
  } else {
    articles.forEach(article => {
      console.log(article.title);
      console.log('评论数:', article.commentCount);
      console.log('评论列表:', article.comments);
    });
  }
});