错误：无法读取未定义的属性（读取“主机”）

Question

I am trying to connect my application to MongoDB, but getting this error 'Error: Cannot read properties of undefined (reading 'host')'. Not able to figure out what might be the problem.

Here is the.env file

PORT=5000;
MONGO_URI ='mongodb+srv://sakshi_0630:<password>@cluster0.lxchu.mongodb.net/?retryWrites=true&w=majority'

db.js file

const mongoose = require("mongoose");
const colors = require("colors");
const connectDB=async()=>{
    try {
        const conn = mongoose.connect(process.env.MONGO_URI, {
            useNewUrlParser: true,
            useUnifiedTopology: true,
            useFindAndModify: true,
        });
        console.log(`MongoDB Connected: ${conn.connection.host}`.cyan.underline);
    } catch (error) {
        console.log(`Error: ${error.message}`.red.bold);
        process.exit();
    }
};
module.exports= connectDB;

server.js

const { response } = require("express");
const express = require("express");
const dotenv = require("dotenv");
const { chats } = require("./data/data");
const connectDB = require("./config/db");

dotenv.config();
connectDB();
const app = express();

Answer 1

You need to await the mongoose.connect() function

const connectDB = async() => {
    try {
        const conn = await mongoose.connect(process.env.MONGO_URI, {
            useNewUrlParser: true,
            useUnifiedTopology: true,
            useFindAndModify: true,
        });
        console.log(`MongoDB Connected: ${conn.connection.host}`.cyan.underline);
    } catch (error) {
        console.log(`Error: ${error.message}`.red.bold);
        process.exit();
    }
};

or use a callback function

mongoose.connect(process.env.MONGO_URI, {
        useNewUrlParser: true,
        useUnifiedTopology: true,
        useFindAndModify: true,
})
.then((conn) => {
    console.log(`MongoDB Connected: ${conn.connection.host}`.cyan.underline);
    //do other things
})
.catch((error) => {
    console.log(`Error: ${error.message}`.red.bold);
    process.exit();
});