CRUD Operations with Express.js and MongoDB

This guide explains how to implement CRUD (Create, Read, Update, Delete) operations using Express.js and MongoDB. CRUD is a fundamental concept for interacting with databases and is essential for most web applications.

Prerequisites

• Basic knowledge of JavaScript, Node.js, and Express.js.
• MongoDB installed locally or access to a MongoDB cloud service (e.g., MongoDB Atlas).
• npm installed.

Project Setup

1. Initialize a Node.js project:

   mkdir crud-express-mongodb
   cd crud-express-mongodb
   npm init -y

1. Install dependencies:

   npm install express mongoose body-parser cors dotenv

1. Create the following folder structure:

   crud-express-mongodb/
   |-- models/
   |-- routes/
   |-- .env
   |-- server.js

Step 1: Setup MongoDB Connection

File: .env

MONGO_URI=mongodb://localhost:27017/crudDB
PORT=5000

File: server.js

const express = require("express");
const mongoose = require("mongoose");
const bodyParser = require("body-parser");
const cors = require("cors");
require("dotenv").config();

const app = express();

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

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

// Routes
const itemRoutes = require("./routes/itemRoutes");
app.use("/api/items", itemRoutes);

// Start Server
const PORT = process.env.PORT || 5000;
app.listen(PORT, () => console.log(`Server running on port ${PORT}`));

Step 2: Create a MongoDB Schema

File: models/Item.js

const mongoose = require("mongoose");

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

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

Step 3: Implement CRUD Routes

File: routes/itemRoutes.js

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

// Create an item
router.post("/", async (req, res) => {
  try {
    const newItem = new Item(req.body);
    const savedItem = await newItem.save();
    res.status(201).json(savedItem);
  } catch (err) {
    res.status(500).json({ error: err.message });
  }
});

// Get all items
router.get("/", async (req, res) => {
  try {
    const items = await Item.find();
    res.status(200).json(items);
  } catch (err) {
    res.status(500).json({ error: err.message });
  }
});

// Get an item by ID
router.get("/:id", async (req, res) => {
  try {
    const item = await Item.findById(req.params.id);
    if (!item) return res.status(404).json({ error: "Item not found" });
    res.status(200).json(item);
  } catch (err) {
    res.status(500).json({ error: err.message });
  }
});

// Update an item by ID
router.put("/:id", async (req, res) => {
  try {
    const updatedItem = await Item.findByIdAndUpdate(req.params.id, req.body, { new: true });
    if (!updatedItem) return res.status(404).json({ error: "Item not found" });
    res.status(200).json(updatedItem);
  } catch (err) {
    res.status(500).json({ error: err.message });
  }
});

// Delete an item by ID
router.delete("/:id", async (req, res) => {
  try {
    const deletedItem = await Item.findByIdAndDelete(req.params.id);
    if (!deletedItem) return res.status(404).json({ error: "Item not found" });
    res.status(200).json({ message: "Item deleted" });
  } catch (err) {
    res.status(500).json({ error: err.message });
  }
});

module.exports = router;

Step 4: Testing the API

Use tools like Postman or cURL to test the following endpoints:

1. Create an item:

   POST /api/items
   Content-Type: application/json
   {
     "name": "Laptop",
     "description": "A powerful laptop",
     "price": 1200
   }

1. Get all items:

   GET /api/items

1. Get an item by ID:

   GET /api/items/:id

1. Update an item:

   PUT /api/items/:id
   Content-Type: application/json
   {
     "name": "Gaming Laptop",
     "description": "A high-end gaming laptop",
     "price": 1500
   }

1. Delete an item:

   DELETE /api/items/:id

The above is the detailed content of CRUD Operations with Express.js and MongoDB. For more information, please follow other related articles on the PHP Chinese website!