javascript - 无法在 Node JS 应用程序中连接 MongoDB

Question

我的应用程序运行良好，并在开发一个简单的 Node js 应用程序时连接到 mongoDB。但突然它开始显示这个错误。这是控制台的快照:

这是我提供 mongoURI 的文件，在出现错误之前它工作得很好:

module.exports = {
  mongoURI:
    "mongodb+srv://glorious:glorious@cluster0-to57n.mongodb.net/test?retryWrites=true&w=majority"
};

这是我的 server.js 文件:

const express = require("express");
const mongoose = require("mongoose");

const app = express();

// DB Config
const db = require("./config/keys").mongoURI;

// Connect to MongoDB
mongoose
  .connect(db)
  .then(() => console.log("MongoDB Connected"))
  .catch(err => console.log(err));

app.get("/", (req, res) => res.send("Hello World"));

const port = process.env.PORT || 5000;

app.listen(port, () => console.log(`Server running on port ${port}`));

这是我的 package.json 文件:

{
  "name": "devconnector",
  "version": "1.0.0",
  "description": "A social network for developers",
  "main": "server.js",
  "scripts": {
    "start": "node server.js",
    "server": "nodemon server.js"
  },
  "author": "Utkarsh Shrivastava",
  "license": "ISC",
  "dependencies": {
    "bcryptjs": "^2.4.3",
    "body-parser": "^1.19.0",
    "express": "^4.17.1",
    "gravatar": "^1.8.0",
    "jsonwebtoken": "^8.5.1",
    "mongoose": "^5.7.13",
    "passport": "^0.4.0",
    "passport-jwt": "^4.0.0",
    "validator": "^12.1.0"
  },
  "devDependencies": {
    "nodemon": "^2.0.1"
  }
}

Answer 1

useNewUrlParser doc :

The useNewUrlParser Option

By default, mongoose.connect() will print out the below warning:

DeprecationWarning: current URL string parser is deprecated, and will
be removed in a future version. To use the new parser, pass option {
useNewUrlParser: true } to MongoClient.connect.

The MongoDB Node.js driver rewrote the tool it uses to parse MongoDB connection strings. Because this is such a big change, they put the new connection string parser behind a flag. To turn on this option, pass the useNewUrlParser option to mongoose.connect() or mongoose.createConnection().

mongoose.connect(uri, { useNewUrlParser: true });
mongoose.createConnection(uri, { useNewUrlParser: true }); 

You can also set the global useNewUrlParser option to turn on useNewUrlParser for every connection by default.

// Optional. Use this if you create a lot of connections and don't
want // to copy/paste `{ useNewUrlParser: true }`.
mongoose.set('useNewUrlParser', true); 

To test your app with {useNewUrlParser: true }, you only need to check whether your app successfully connects. Once Mongoose has successfully connected, the URL parser is no longer important. If you can't connect with { useNewUrlParser: true }, please open an issue on GitHub.

useUnifiedTopology doc :

useUnifiedTopology

By default, mongoose.connect() will print out the below warning:

DeprecationWarning: current Server Discovery and Monitoring engine is
deprecated, and will be removed in a future version. To use the new
Server Discover and Monitoring engine, pass option {
useUnifiedTopology: true } to the MongoClient constructor. 

Mongoose 5.7 uses MongoDB driver 3.3.x, which introduced a significant refactor of how it handles monitoring all the servers in a replica set or sharded cluster. In MongoDB parlance, this is known as server discovery and monitoring.

To opt in to using the new topology engine, use the below line:

mongoose.set('useUnifiedTopology', true); 

If you find any unexpected behavior, please open up an issue on GitHub.

因此您需要将两个选项传递给 mongoose.connect:

// Connect to MongoDB
mongoose
  .connect(db, { useNewUrlParser: true, useUnifiedTopology: true })
  ...