使用 `connect-mongo` 和带有 MongoDB Atlas 的 Mongoose 的计时问题

Question

我正在使用 connect-mongo for my ExpressJS Session Store and Mongoose 进行我的数据库连接，我将称之为时间问题。这是我的代码：

dbservice.js

const mongoose = require('mongoose');
const debug = require('debug')('app:core:db:service');
const chalk = require('chalk');
const config = require('config');

const mongoDbUrl = config.mongodb_url;

const mongoDbOptions = {
  useUnifiedTopology: true,
  useNewUrlParser: true,
  useCreateIndex: true,
  useFindAndModify: false,
};
(async () => {
  try {
    await mongoose.connect(mongoDbUrl, mongoDbOptions);
    debug(`Connected to ${chalk.green('MongoDB')}`);
  } catch (err) {
    debug(`${chalk.green('MongoDB')} connection ${chalk.red(`error`)}: ${err}`);
  }
})();
const db = mongoose.connection;
db.on('error', (err) => {
  debug(`${chalk.green('MongoDB')} connection ${chalk.red(`error`)}: ${err}`);
});
// For nodemon restarts
process.once('SIGUSR2', () => {
  const msg = 'Nodemon Restart';
  db.close()
    .then(() => {
      debug(`${chalk.green('MongoDB')} connection ${chalk.red(`closed`)}: ${msg}`);
      process.kill(process.pid, 'SIGUSR2');
    })
    .catch((err) => {
      debug(err);
    });
});
const dbClient = db.getClient();

module.exports = dbClient;

app.js

const dbClient = require('dbService');

// Using Express Session with Google Cloud Datastore to securly store session/cookie information
app.use(
  session({
    // Using MongoDB as session store
    store: MongoStore.create({
      client: dbClient, // Use Mongoose for DB Conection
      ttl: 1800000, // Ages session out at 30 minutes
      autoRemove: 'native', // Uses MongoDB's native Time to Live (TTL) to expire and remove records
      },
    }),
  }),
);

此代码在使用 MongoDB 的本地网络实例时效果很好，因为连接到 MongoDB 的延迟非常小，因此它可以正常工作。但是，当使用 MongoDB Atlas 时，连接会有一到两秒的延迟。所以，我怀疑（我认为很棒的）我在 dbservice.js 中的代码行 const dbClient = db.getClient() 失败了 connect-mongo 抛出错误：

(node:1148) UnhandledPromiseRejectionWarning: MongoError: MongoClient must be connected before calling MongoClient.prototype.db` because Mongoose is not connected.

作为新手，我一直在努力尝试解决这个问题。我试图找到一种方法来使用 mongoose.connection.readyState 等待它 returned a 1 连接但失败了。

我的问题是：有没有更好的方法让我 return dbClient 正确等待 Mongoose 连接到 MongoDB？非常感谢任何帮助。

Answer 1

您没有从 dbservice.js

中返回 Promise

(async () => {})()

对异步代码没有意义

您的代码应该是这样的

const getDbClient = async () => {
  try {
    await mongoose.connect(mongoDbUrl, mongoDbOptions);
    debug(`Connected to ${chalk.green('MongoDB')}`);
    const db = mongoose.connection;
    return db.getClient()
  } catch (err) {
    debug(`${chalk.green('MongoDB')} connection ${chalk.red(`error`)}: ${err}`);
  }
}

function async start() {
  const client = await getDbClient()
    // Using Express Session with Google Cloud Datastore to securly store session/cookie         information
  app.use(
    session({
      // Using MongoDB as session store
      store: MongoStore.create({
        client: client, // Use Mongoose for DB Conection
        ttl: 1800000, // Ages session out at 30 minutes
        autoRemove: 'native', // Uses MongoDB's native Time to Live (TTL) to expire and        remove records
        },
      }),
    }),
  );
  // Here is server startup code.... app.listen etc.
}

start.then(() => console.log('started'))

Answer 2

根据 Nikita Mazur 的回复，我将 dbservices.js 修改为以下内容：

const mongoose = require('mongoose');
const debug = require('debug')('app:core:db:service');
const chalk = require('chalk');
const { mongoDbUrl } = require('../config/config');

const mongoDbOptions = {
  useUnifiedTopology: true,
  useNewUrlParser: true,
  useCreateIndex: true,
  useFindAndModify: false,
};
async function dbConnection() {
  try {
    await mongoose.connect(mongoDbUrl, mongoDbOptions);
    debug(`Connected to ${chalk.green('MongoDB')}`);
  } catch (err) {
    debug(`${chalk.green('MongoDB')} connection ${chalk.red(`error`)}: ${err}`);
  }
  return mongoose.connection.getClient();
}
const db = mongoose.connection;
db.on('error', (err) => {
  debug(`${chalk.green('MongoDB')} connection ${chalk.red(`error`)}: ${err}`);
});
// For nodemon restarts
process.once('SIGUSR2', () => {
  const msg = 'Nodemon Restart';
  db.close()
    .then(() => {
      debug(`${chalk.green('MongoDB')} connection ${chalk.red(`closed`)}: ${msg}`);
      process.kill(process.pid, 'SIGUSR2');
    })
    .catch((err) => {
      debug(err);
    });
});

module.exports = dbConnection();

使用 `connect-mongo` 和带有 MongoDB Atlas 的 Mongoose 的计时问题

Timing issue using `connect-mongo` and Mongoose with MongoDB Atlas

node.js

mongodb

mongoose

connect-mongo