然后將 nodemon 服務器與 MongoDB 連接時出錯

Question

我試圖將我的節點服務器與我的 MongoDB 數據庫連接起來，但我一直遇到這個錯誤，我對節點和 mongodb 非常陌生，我嘗試將 useUnifiedTopology:true 放入我的 mongo 構造函數中？ 我不確定我在哪里搞砸了。

const cors = require('cors');
const mongoose = require('mongoose');

require('dotenv').config();

const app = express();
const port = process.env.PORT || 5000;

app.use(cors());
app.use(express.json());

const uri = process.env.ATLAS_URI;
mongoose.connect(uri, { useNewUrlParser: true, useCreateIndex: true,useUnifiedTopology: true}
);
const connection = mongoose.connection;
connection.once('open', () => {
  console.log("MongoDB database connection established successfully");
})

// const exercisesRouter = require('./routes/exercises');
// const usersRouter = require('./routes/users');

// app.use('/exercises', exercisesRouter);
// app.use('/users', usersRouter);

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




```Server is running on port: 5000
(node:21667) UnhandledPromiseRejectionWarning: MongoNetworkError: connection 0 to cluster0-shard-00-00-rsjfl.gcp.mongodb.net:27017 closed
    at TLSSocket.<anonymous> (/Users/MYNAME/Desktop/ExcersizeTracker/mern-excersize/backend/node_modules/mongodb/lib/core/connection/connection.js:352:9)
    at Object.onceWrapper (events.js:284:20)
    at TLSSocket.emit (events.js:196:13)
    at net.js:586:12
    at TCP.done (_tls_wrap.js:466:7)
(node:21667) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:21667) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code```

Answer 1

這是官方文檔中的連接指南：

const MongoClient = require('mongodb').MongoClient;
const assert = require('assert');

// Connection URL
const url = 'mongodb://localhost:27017';

// Database Name
const dbName = 'myproject';

// Create a new MongoClient
const client = new MongoClient(url);

// Use connect method to connect to the Server
client.connect(function(err) {
  assert.equal(null, err);
  console.log("Connected successfully to server");

  const db = client.db(dbName);

  client.close();
});

Answer 2

連接方法是異步的。 您必須等待完成才能繼續。

...
(async () => {
   await mongoose.connect(uri, {useNewUrlParser: true, useCreateIndex: true, useUnifiedTopology: true});
})();
...