Now you move from temporary data (arrays) โ real database storage.
Backend apps must store data permanently.
That's where databases come in.
๐ง What is a Database
A database stores data persistently.
Examples:
โข E-commerce: Products, orders
โข Social media: Users, posts
โข Banking app: Transactions
Without database โ data disappears when server restarts.
๐ What is MongoDB
MongoDB is a NoSQL database.
Instead of tables โ it stores documents (JSON-like data).
Example document:
{
"name": "Deepak",
"role": "Developer",
"age": 25
}
Collection = group of documents
Database = group of collections
๐ฆ Why MongoDB is Popular
โ JSON-like data
โ Flexible schema
โ Works perfectly with JavaScript
โ Scales easily
Common in MERN stack.
MERN = MongoDB + Express + React + Node
๐ Connecting MongoDB with Node.js
We use a library called Mongoose.
Install:
npm install mongoose
โก Step 1 โ Connect Database
Example:
const mongoose = require("mongoose");
mongoose.connect("mongodb://127.0.0.1:27017/myapp")
.then(() => console.log("MongoDB Connected"))
.catch(err => console.log(err));
Now Node server is connected to MongoDB.
๐งฉ Step 2 โ Create Schema
Schema defines data structure.
Example:
const userSchema = new mongoose.Schema({
name: String,
age: Number
});
๐ Step 3 โ Create Model
Model allows database operations.
const User = mongoose.model("User", userSchema);
โ Step 4 โ Create Data
app.post("/users", async (req, res) => {
const user = new User({
name: req.body.name,
age: req.body.age
});
await user.save();
res.json(user);
});
๐ Step 5 โ Fetch Data
app.get("/users", async (req, res) => {
const users = await User.find();
res.json(users);
});
โ Step 6 โ Delete Data
app.delete("/users/:id", async (req, res) => {
await User.findByIdAndDelete(req.params.id);
res.json({ message: "User deleted" });
});
โ๏ธ Step 7 โ Update Data
app.put("/users/:id", async (req, res) => {
const user = await User.findByIdAndUpdate(
req.params.id,
req.body,
{ new: true }
);
res.json(user);
});
๐ Full Backend Flow Now
React โ API request
Express โ Handles route
Mongoose โ Talks to MongoDB
MongoDB โ Stores data
โ ๏ธ Common Beginner Mistakes
โข Forgetting to install mongoose
โข Not using async/await
โข Wrong MongoDB URL
โข Not validating schema
๐งช Mini Practice Task
Build Product API with MongoDB
Routes:
โข POST /products
โข GET /products
โข PUT /products/:id
โข DELETE /products/:id
Fields:
name
price
category
โ Double Tap โฅ๏ธ For More