Crafting High-Performance RESTful APIs with ExpressJS

Building RESTful APIs with Express.js involves setting up a Node.js server using Express, defining routes to handle various HTTP methods (GET, POST, PUT, DELETE), and managing requests and responses with middleware. You can integrate a database like MongoDB for data persistence and implement error handling, authentication, and security measures as needed. Finally, deploy the API to a cloud platform like Heroku or AWS for production use.

Prerequisites:

• ExpressJs
• NodeJs
• Javascript

Approach

• Start by importing Express in your index.js. Initialize the Express app using const app = express();.
• Set a port for the server to listen on, e.g., const PORT = 3000;.
• Use app.get(), app.post(), app.put(), app.delete() to define routes for various HTTP methods.
• Capture dynamic parameters in routes using :param, e.g., app.get('/user/:id', (req, res) => {...}).
• Access query parameters using req.query, e.g., req.query.name. Use middleware like app.use(express.json()) to parse incoming JSON requests.
• Send responses using res.send(), res.json(), or res.status() to set HTTP status codes.

Steps to Create RESTful APIs with Express.js

Step 1: Setting Up the Project

• Initialize the Project: Run npm init to create a package.json file on your terminal.

MKDIR RESTFUL
cd RESTFUL
npm init

• Install Dependencies: Install Express and other necessary packages using npm install express.

npm install express mongoose

Updated Dependencies

"dependencies": {
    "express": "^4.19.2",
    "mongoose": "^8.5.2"
  }

Project Structure:

Example: This example shows the creation of RESTful API.

// index.js

const express = require("express");
const connectDB = require("./db");
const mongoose = require("mongoose");

const app = express();
const PORT = process.env.PORT || 3000;

// Connect to MongoDB
connectDB();

// Create a User schema and model
const UserSchema = new mongoose.Schema({
    name: { type: String, required: true },
    id: { type: Number, required: true }
});

const User = mongoose.model("User", UserSchema);

app.use(express.json());

app.get("/", async (req, res) => {
    const users = await User.find();
    res.json(users);
});

app.get("/api/users/:id", async (req, res) => {
    const user = await User.findById(req.params.id);
    if (!user) return res.status(404).send("User not found");
    res.json(user);
});

app.post("/api/users", async (req, res) => {
    const newUser = new User({ name: req.body.name, id: req.body.id });
    await newUser.save();
    res.status(201).json(newUser);
});

app.put("/api/users/:id", async (req, res) => {
    const user = await User.findById(req.params.id);
    if (!user) return res.status(404).send("User not found");

    user.name = req.body.name;
    await user.save();
    res.json(user)
});

app.delete("/api/users/:id", async (req, res) => {
    const user = await User.findById(req.params.id);
    console.log(user)
    if (!user) return res.status(404).send("User not found");

    await User.deleteOne({ _id: req.params.id });
    res.json(user)
});

app.listen(PORT, () => {
    console.log(`Server running on port ${PORT}`);
});

// db.js

const mongoose = require("mongoose");

const connectDB = async () => {
    try {
        await mongoose.connect(
            process.env.MONGO_URI || "mongodb://localhost:27017/Exp");
        console.log("MongoDB connected");
    } catch (err) {
        console.error(err.message);
        process.exit(1);
    }
};

module.exports = connectDB;

Output:

Steps to Test the API using Postman

1. POST Request:

• Make the request type to POST .
• Enter http://localhost:3000/api/users in the request URL.
• The “Body” tab can be selected, and under the “Data format”, choose “Raw” that can be “JSON”.
• Add the following JSON data:

{
     "name":"John",
     "id":3
}

• Click “Send. “
• Post this you should see a success message and the new user should be stored in the database.

2. DELETE Request:

• Modify the request type to delete.
• Enter http://localhost:3000/api/users/user_id of the user to the request URL (provided there is a user with such ID).
• Click “Send. “
• You should be seeing a success message and in the database, the user will be deleted.

3. PUT Request:

• Alters the request type to PUT.
• Enter http://localhost:3000/api/users/user_id in the request URL.
• In the “Body” tab, add the updated JSON data:

{"name": "John Deo"}

• Click “Send. “
• There should be a success message and after that, the user information will be modified in the database.

4. GET Request:

• Open Postman.
• Specify the request type to Get.
• Enter http://localhost:3000 at the end of the request URL.
• Click “Send. “
• Looking at the JSON response, you should be able to get all the users currently in the database.

Steps to Run Project:

Navigate inside the folder RESTFUl and enter the following command to start the project:

node index.js

Output: