MERN Stack Tutorial Guide Doesn't Work

MongoDB Atlas
,
5

Hello @53ac1da52812ebe8d38b9c0f38be5d9,

Thanks for sharing the detailed explanation.

The cause for this issue is that the repository uses an older version of the MongoDB node.js driver, specifically, version "mongodb": "^3.6.6". On the other hand, when you create your own project and install the MongoDB node.js driver package, it installs the latest version, which is "mongodb": "^5.3.0".

However, the latest version is incompatible with the code written in the tutorial because it uses the callback function which is deprecated in the new MongoDB node.js driver 5.0.0.

Reference: Changelog - node-mongodb-native.

If you want to follow the tutorial and build the project successfully, you have to use MongoDB version mongodb@4.16.0 or a lower version.

To resolve this problem and make your project functional, you must delete the node_module directory and modify the MongoDB version in your package.json file to "mongodb": "^4.16.0" or a lower version.

Another workaround is to use the latest node.js driver version and modify the functions that use a callback by switching to the Promise and async/await syntax instead.

As an example, you can update the content of the db/conn.js file to incorporate async/await. Sharing code snippet for your reference:

const { MongoClient } = require("mongodb");
const Db = process.env.ATLAS_URI;
const client = new MongoClient(Db, {
    useNewUrlParser: true,
    useUnifiedTopology: true,
});

let _db;

module.exports = {
    connectToServer: async function () {
        try {
            const db = await client.connect();
            // Verify we got a good "db" object
            if (db) {
                _db = db.db("employees");
                console.log("Successfully connected to MongoDB.");
            }
            return _db;
        } catch (err) {
            throw err;
        }
    },

    getDb: function () {
        return _db;
    },
};

Similarly, you can modify the function in routes/record.js.

I hope this helps. If you have any further questions, please let us know.

Best,
Kushagra

2 Likes