Building a REST API with Node.js and Express

Creating Your First REST API

REST APIs are the backbone of modern web applications. Let’s build one from scratch using Node.js and Express.

Setting Up the Project

First, initialize a new Node.js project and install dependencies:

mkdir my-api
cd my-api
npm init -y
npm install express mongoose dotenv cors
npm install --save-dev nodemon

Creating the Server

Create server.js and set up a basic Express server:

const express = require("express");
const mongoose = require("mongoose");
const cors = require("cors");
require("dotenv").config();

const app = express();

// Middleware
app.use(express.json());
app.use(cors());

// Basic route
app.get("/", (req, res) => {
  res.json({ message: "Welcome to my API" });
});

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
  console.log(`Server running on port ${PORT}`);
});

Connecting to MongoDB

Add database connection in server.js:

mongoose
  .connect(process.env.MONGODB_URI, {
    useNewUrlParser: true,
    useUnifiedTopology: true,
  })
  .then(() => console.log("MongoDB connected"))
  .catch((err) => console.error("MongoDB connection error:", err));

Creating a Model

Create models/Item.js:

const mongoose = require("mongoose");

const itemSchema = new mongoose.Schema(
  {
    name: {
      type: String,
      required: true,
      trim: true,
    },
    description: {
      type: String,
      required: true,
    },
    price: {
      type: Number,
      required: true,
      min: 0,
    },
    category: {
      type: String,
      required: true,
    },
  },
  {
    timestamps: true,
  },
);

module.exports = mongoose.model("Item", itemSchema);

Defining RESTful Routes

Create routes/items.js:

const express = require("express");
const router = express.Router();
const Item = require("../models/Item");

// GET all items
router.get("/", async (req, res) => {
  try {
    const items = await Item.find();
    res.json(items);
  } catch (error) {
    res.status(500).json({ message: error.message });
  }
});

// GET single item
router.get("/:id", async (req, res) => {
  try {
    const item = await Item.findById(req.params.id);
    if (!item) return res.status(404).json({ message: "Item not found" });
    res.json(item);
  } catch (error) {
    res.status(500).json({ message: error.message });
  }
});

// POST new item
router.post("/", async (req, res) => {
  const item = new Item(req.body);
  try {
    const newItem = await item.save();
    res.status(201).json(newItem);
  } catch (error) {
    res.status(400).json({ message: error.message });
  }
});

// PUT update item
router.put("/:id", async (req, res) => {
  try {
    const item = await Item.findByIdAndUpdate(req.params.id, req.body, {
      new: true,
      runValidators: true,
    });
    if (!item) return res.status(404).json({ message: "Item not found" });
    res.json(item);
  } catch (error) {
    res.status(400).json({ message: error.message });
  }
});

// DELETE item
router.delete("/:id", async (req, res) => {
  try {
    const item = await Item.findByIdAndDelete(req.params.id);
    if (!item) return res.status(404).json({ message: "Item not found" });
    res.json({ message: "Item deleted" });
  } catch (error) {
    res.status(500).json({ message: error.message });
  }
});

module.exports = router;

Error Handling Middleware

Add to server.js:

// Error handling middleware
app.use((err, req, res, next) => {
  console.error(err.stack);
  res.status(500).json({ message: "Something went wrong!" });
});

Testing Your API

Use Postman or curl to test endpoints:

# Get all items
curl http://localhost:3000/api/items

# Create new item
curl -X POST http://localhost:3000/api/items \
  -H "Content-Type: application/json" \
  -d '{"name":"Item 1","description":"Description","price":29.99,"category":"Electronics"}'

# Get single item
curl http://localhost:3000/api/items/:id

# Update item
curl -X PUT http://localhost:3000/api/items/:id \
  -H "Content-Type: application/json" \
  -d '{"price":24.99}'

# Delete item
curl -X DELETE http://localhost:3000/api/items/:id

Adding Authentication

Install JWT packages:

npm install jsonwebtoken bcryptjs

Create authentication middleware and protect routes as needed.

Conclusion

You now have a fully functional REST API! Next steps could include adding authentication, pagination, filtering, and deploying to production.

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