Mongoose中间件级联删除

const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost:27017/test', { useNewUrlParser: true, useUnifiedTopology: true });

const Schema = mongoose.Schema;

// 定义一个 User 模型
const userSchema = new Schema({
  name: String,
  email: String
});

// 定义一个 Post 模型，其中 author 字段引用 User 模型
const postSchema = new Schema({
  title: String,
  content: String,
  author: { type: Schema.Types.ObjectId, ref: 'User' }
});

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

// 在 User 模型上添加 pre('remove') 中间件，实现级联删除
userSchema.pre('remove', async function(next) {
  await Post.deleteMany({ author: this._id });
  next();
});

// 示例：删除用户及其所有帖子
(async () => {
  const user = await User.create({ name: 'John Doe', email: 'john@example.com' });
  await Post.create({ title: 'First Post', content: 'This is the first post', author: user._id });

  await user.remove();
  console.log('User and associated posts deleted');
})();