Can't retrieve information from mongodb when deploying on heroku - node.js

Question

The problem is as the title suggests. When I run my app locally, I'm able to retrieve information from MongoDB but on Heroku, undefined is returned. Should I connect to MongoDB in another way because if I hardcode some text everything works just fine. Here are my scripts:
function to get data
const MongoClient = require("mongodb").MongoClient;
const dbConnectionUrl = "mongodb+srv://xxxxxxx#cluster0.ro4dz.mongodb.net/data?retryWrites=true&w=majority";
const saySomething = (req, res, next) => {
// res.status(200).json({
// body: 'Hello from the server!'
// });
login()
.then(val=>res.send(val))
};
async function login(){
const client = new MongoClient(dbConnectionUrl)
try{
await client.connect();
const database = client.db("data");
const movies = database.collection("movies");
const query = { name: "toke" };
const movie = await movies.findOne(query);
return movie
}catch(err){
console.log(err)
}
}
module.exports.saySomething = saySomething;
router
const express = require('express');
const router = express.Router();
const controllers = require('./../controllers/controllers');
router.get('/say-something', controllers.saySomething);
module.exports = router;
server
// Import dependencies
const express = require('express');
const cors = require('cors');
const path = require('path');
// Create a new express application named 'app'
const app = express();
// Set our backend port to be either an environment variable or port 5000
const port = process.env.PORT || 5000;
// This application level middleware prints incoming requests to the servers console, useful to see incoming requests
app.use((req, res, next) => {
console.log(`Request_Endpoint: ${req.method} ${req.url}`);
next();
});
// Configure the CORs middleware
// Require Route
app.use(cors());
const api = require('./routes/routes');
// Configure app to use route
app.use('/api', api);
// This middleware informs the express application to serve our compiled React files
if (process.env.NODE_ENV === 'production' || process.env.NODE_ENV === 'staging') {
app.use(express.static(path.join(__dirname, 'client/build')));
app.get('*', function (req, res) {
res.sendFile(path.join(__dirname, 'client/build', 'index.html'));
});
};
// Catch any bad requests
app.get('*', (req, res) => {
res.status(200).json({
msg: 'Catch All'
});
});
// Configure our server to listen on the port defiend by our port variable
app.listen(port, () => console.log(`BACK_END_SERVICE_PORT: ${port}`));
front
import { useEffect, useState } from 'react';
import './App.css';
import axios from 'axios'
function App(){
useEffect(()=>{
get()
})
const[text, settext] = useState('')
async function get(){
let request = await axios.get('/api/say-something')
console.log(request.data.name)
settext(request.data.name)
}
return(
<div>{text}</div>
)
}
export default App;

Answer 1

I solved the issue! The first thing I did was that I added MongoDB connection URI as an environmental variable in my app via Heroku. Secondly, I added an option in MongoDB so that the cluster can be accessed from any computer. By default, the access is set to the local computer so I added another IP, namely 0.0.0.0/0 to my cluster, and now everything works just fine.