在mongoose中级联创建/删除集合的好方法

const mongoose = require('mongoose');

// 定义B模型
const BSchema = new mongoose.Schema({
  name: String
});

const B = mongoose.model('B', BSchema);

// 定义A模型
const ASchema = new mongoose.Schema({
  name: String,
  b: {
    type: mongoose.Schema.Types.ObjectId,
    ref: 'B'
  }
});

const A = mongoose.model('A', ASchema);

const aData = {
  name: 'A1',
  b: {
    name: 'B1'
  }
};

A.create(aData)
  .then(a => {
    console.log('A created:', a);
  })
  .catch(err => {
    console.error('Error creating A:', err);
  });

ASchema.pre('remove', function(next) {
  B.deleteOne({ _id: this.b })
    .then(() => {
      next();
    })
    .catch(err => {
      next(err);
    });
});

A.deleteOne({ _id: aId })
  .then(() => {
    console.log('A deleted');
  })
  .catch(err => {
    console.error('Error deleting A:', err);
  });