过滤Mongoose数组的结果并填充objectId的子字段

const mongoose = require('mongoose');

const postSchema = new mongoose.Schema({
  objectId: {
    type: mongoose.Schema.Types.ObjectId,
    ref: 'Post'
  },
  // 其他字段...
});

const userSchema = new mongoose.Schema({
  // 其他字段...
  posts: [{
    type: mongoose.Schema.Types.ObjectId,
    ref: 'Post'
  }]
});

const User = mongoose.model('User', userSchema);
const Post = mongoose.model('Post', postSchema);

User.find({}).populate({
  path: 'posts',
  match: { /* 过滤条件 */ },
  select: 'objectId' // 只选择objectId字段
}).exec((err, users) => {
  if (err) {
    console.error(err);
    return;
  }
  
  // 处理查询结果
  users.forEach(user => {
    user.posts = user.posts.filter(post => post.objectId); // 过滤掉没有objectId的子字段
  });
  
  console.log(users);
});