使用`connect-mongo`和Mongoose与MongoDB Atlas的时间问题

问题描述

我将 connect-mongo 用于我的 Expressjs 会话存储，Mongoose 用于我的数据库连接，并且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 @R_729_4045@ion
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
      },}),);

当使用 MongoDB 的本地网络实例时，此代码非常有效，因为连接到 MongoDB 的延迟非常小，因此它可以工作。但是，在使用 MongoDB Atlas 时，连接会有一到两秒的延迟。所以，我怀疑（我认为很棒）我在 const dbClient = db.getClient() 中的代码行 dbservice.js 失败，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。我试图找到一种使用 mongoose.connection.readyState 等待直到它返回 1 表示已连接但失败的方法。

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

解决方法

您没有从 dbservice.js 返回 Promise

(async () => {})()

对异步代码毫无意义

你的代码应该是什么样子

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'))

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();

connect-mongo mongodb mongoose