How to Connect Node to a MongoDB Database ?

Last Updated : 14 Jan, 2024

MongoDB is a NoSQL database used to store large amounts of data without any traditional relational database table. Instead of rows & columns, MongoDB used collections & documents to store data. A collections consist of a set of documents & a document consists of key-value pairs which are the basic unit of data in MongoDB.

Make sure that MongoDB installs on your PC.

To connect a Node.js application to MongoDB, we have to use a library called Mongoose.

const mongoose = require("mongoose");

After that, we have to call the connect method of Mongoose

mongoose.connect("mongodb://localhost:27017/collectionName", {
   useNewUrlParser: true,
   useUnifiedTopology: true
});

Then we have to define a schema. A schema is a structure, that gives information about how the data is being stored in a collection.

Example: Suppose we want to store information from a contact form of a website.

const contactSchema = {
   email: String,
   query: String,
};

Then we have to create a model using that schema which is then used to store data in a document as objects.

const Contact = mongoose.model("Contact", contactSchema);

Then, finally, we are able to store data in our document.

app.post("/contact", function (req, res) {
   const contact = new Contact({
       email: req.body.email,
       query: req.body.query,
   });
   contact.save(function (err) {
       if (err) {
           res.redirect("/error");
       } else {
           res.redirect("/thank-you");
       }
   });
});

Example: Below is the code example of how to connect node.js to a mongodb database.

Javascript

const express = require("express");
const ejs = require("ejs");
const mongoose = require("mongoose");
const bodyParser = require("body-parser");
 
mongoose.connect(
"mongodb://localhost:27017/newCollection",
    {
        useNewUrlParser: true,
        useUnifiedTopology: true
    });
 
const contactSchema = {
    email: String,
    query: String,
};
 
const Contact =
    mongoose.model("Contact", contactSchema);
 
const app = express();
 
app.set("view engine", "ejs");
 
app.use(bodyParser.urlencoded({
    extended: true
}));
 
app.use(express.static(__dirname + '/public'));
 
app.get("/contact",
    function (req, res) {
        res.render("contact");
    });
 
app.post("/contact",
    function (req, res) {
        console.log(req.body.email);
        const contact = new Contact({
            email: req.body.email,
            query: req.body.query,
        });
        contact.save(function (err) {
            if (err) {
                throw err;
            } else {
                res.render("contact");
            }
        });
    });
 
app.listen(3000,
    function () {
        console.log("App is running on Port 3000");
    });

HTML

<!DOCTYPE html>
<html lang="en">
 
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible"
          content="IE=edge">
    <meta name="viewport"
          content="width=device-width, 
                   initial-scale=1.0">
    <title>Document</title>
</head>
 
<body>
    <form action="/contact" method="post">
        <input type="text"
               placeholder="Email"
               name="email">
        <input type="text"
               placeholder="Query"
               name="query">
        <button type="submit">
            Submit
        </button>
    </form>
</body>
 
</html>