如何过滤猫鼬changeStream

Question

我正在做一个聊天系统，我尝试使用mongoDB/mongoose的changeStream。

如果当前用户是收件人，我只想获取文档，但它不起作用。到目前为止，我遇到了两个案例。一个从不触发，另一个与所有文档一起返回，即使当前用户不是收件人。

区别在于数组中的管道与否。

你知道什么是正确的语法吗？

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我阅读了过去 2 天在谷歌前 10 页找到的所有文章，但没有一篇包含如何过滤。据我了解，聚合管道仅用于操作结果，但无法排除未通过条件的文档。

---

这是我所做的：

const pipeline = [{
     $match: { 
         "userId": this.recipient.id,
         "recipientId": this.user.id
    }
}]

const stream = MessageModel.watch(pipeline )

stream.on('change', (data: any) => {
    console.log(`messages changed`);
    this.socketIo.sockets.in(this.socket.id).emit(`protected/message/subscribe/${this.msg.msgId}`, data.fullDocument);
});

Answer 1

这可能有用

const { ReplSet } = require('mongodb-topology-manager');
const mongoose = require('mongoose');

run().catch(error => console.error(error));

async function run() {
  console.log(new Date(), 'start');
  const bind_ip = 'localhost';
  // Starts a 3-node replica set on ports 31000, 31001, 31002, replica set
  // name is "rs0".
  const replSet = new ReplSet('mongod', [
    { options: { port: 31000, dbpath: `${__dirname}/data/db/31000`, bind_ip } },
    { options: { port: 31001, dbpath: `${__dirname}/data/db/31001`, bind_ip } },
    { options: { port: 31002, dbpath: `${__dirname}/data/db/31002`, bind_ip } }
  ], { replSet: 'rs0' });

  // Initialize the replica set
  await replSet.purge();
  await replSet.start();
  console.log(new Date(), 'Replica set started...');

  // Connect to the replica set
  const uri = 'mongodb://localhost:31000,localhost:31001,localhost:31002/' +
    'test?replicaSet=rs0';
  await mongoose.connect(uri);

  // To work around "MongoError: cannot open $changeStream for non-existent
  // database: test" for this example
  await mongoose.connection.createCollection('people');

  const Person = mongoose.model('Person', new mongoose.Schema({ name: String }));

  // Create a change stream. The 'change' event gets emitted when there's a
  // change in the database
  Person.watch().
    on('change', data => console.log(new Date(), data));

  // Insert a doc, will trigger the change stream handler above
  console.log(new Date(), 'Inserting doc');
  await Person.create({ name: 'Axl Rose' });
  console.log(new Date(), 'Inserted doc');
}