How to Connect Node.js to a MongoDB Database ?
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");
}
});
});Now let’s understand the working with the help of a code example.
Contact.ejs
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> |
Server File ( App.js or Index.js )
Javascript
const express = require("express");const ejs = require("ejs");const mongoose = require("mongoose");const bodyParser = require("body-parser"); 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");}); |
Output:
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