删除账号时，如何正确级联删除MongoDB中的辅助对象？

const { MongoClient } = require('mongodb');

async function main() {
  const uri = 'your_mongodb_connection_string';
  const client = new MongoClient(uri, { useNewUrlParser: true, useUnifiedTopology: true });

  try {
    await client.connect();
    const database = client.db('your_database_name');
    const usersCollection = database.collection('users');
    const ordersCollection = database.collection('orders');

    // 删除用户
    const userId = 'some_user_id';
    await usersCollection.deleteOne({ _id: userId });

    // 删除该用户的所有订单
    await ordersCollection.deleteMany({ userId: userId });
  } finally {
    await client.close();
  }
}

main().catch(console.error);

const { MongoClient } = require('mongodb');

async function createTrigger() {
  const uri = 'your_mongodb_connection_string';
  const client = new MongoClient(uri, { useNewUrlParser: true, useUnifiedTopology: true });

  try {
    await client.connect();
    const database = client.db('your_database_name');
    const usersCollection = database.collection('users');

    // 创建触发器
    await usersCollection.createIndex({ _id: 1 }, { partialFilterExpression: { _id: 'some_user_id' } });
    await database.command({
      createTrigger: 'cascadeDeleteTrigger',
      collection: usersCollection.namespace,
      trigger: {
        operationType: 'delete',
        fullDocument: 'updateLookup',
        update: { $pull: { orders: { userId: '$$ROOT._id' } } },
        when: { $expr: { $eq: ['$operationType', 'delete'] } }
      }
    });
  } finally {
    await client.close();
  }
}

createTrigger().catch(console.error);

const { MongoClient } = require('mongodb');

async function deleteUser() {
  const uri = 'your_mongodb_connection_string';
  const client = new MongoClient(uri, { useNewUrlParser: true, useUnifiedTopology: true });

  try {
    await client.connect();
    const database = client.db('your_database_name');
    const usersCollection = database.collection('users');

    // 删除用户
    const userId = 'some_user_id';
    await usersCollection.deleteOne({ _id: userId });
  } finally {
    await client.close();
  }
}

deleteUser().catch(console.error);