Comprehensive Project: E-commerce Review System (6 Modules)

shophub-reviews/
├── package.json
├── .env
├── .env.example
├── src/
│   ├── app.js              # Express Applications
│   ├── config/
│   │   └── db.js          # mongoose Connect
│   ├── models/            # Data Model
│   │   ├── User.js
│   │   ├── Product.js
│   │   └── Review.js
│   ├── controllers/       # Business Logic
│   │   ├── authController.js
│   │   ├── productController.js
│   │   └── reviewController.js
│   ├── routes/            # Routing
│   │   ├── auth.js
│   │   ├── products.js
│   │   └── reviews.js
│   ├── middlewares/       # Middleware
│   │   ├── auth.js        # JWT Certification
│   │   ├── errorHandler.js
│   │   └── validate.js
│   ├── validators/        # Request for a Trial Certificate
│   │   └── schemas.js
│   └── utils/             # Tools
│       ├── logger.js
│       └── jwt.js
└── README.md

{
  "name": "shophub-reviews",
  "version": "1.0.0",
  "scripts": {
    "start": "node src/app.js",
    "dev": "nodemon src/app.js",
    "test": "jest --watch"
  },
  "dependencies": {
    "express": "^4.19.2",
    "mongoose": "^7.6.0",
    "jsonwebtoken": "^9.0.0",
    "bcrypt": "^5.1.0",
    "joi": "^17.13.0",
    "dotenv": "^16.4.0",
    "cors": "^2.8.5"
  },
  "devDependencies": {
    "nodemon": "^3.1.0",
    "jest": "^29.7.0"
  }
}

NODE_ENV=development
PORT=3000
MONGODB_URI=mongodb://localhost:27017/shophub
JWT_SECRET=your-super-secret-key-change-in-prod
JWT_EXPIRES_IN=7d

// models/User.js
const mongoose = require('mongoose');
const bcrypt = require('bcrypt');

const UserSchema = new mongoose.Schema({
  email: {
    type: String,
    required: [true, 'Email is required'],
    unique: true,
    lowercase: true,
    trim: true,
    match: [/^\S+@\S+\.\S+$/, 'Invalid email format']
  },
  username: {
    type: String,
    required: true,
    unique: true,
    minlength: 3,
    maxlength: 30,
    match: [/^[a-zA-Z0-9_]+$/, 'Alphanumeric + underscore only']
  },
  passwordHash: {
    type: String,
    required: true,
    minlength: 60,  // bcrypt hash Length
    select: false
  },
  role: {
    type: String,
    enum: ['customer', 'admin', 'moderator'],
    default: 'customer'
  },
  isActive: { type: Boolean, default: true }
}, { timestamps: true });

// Password Hashing Middleware
UserSchema.pre('save', async function(next) {
  if (!this.isModified('passwordHash')) return next();
  this.passwordHash = await bcrypt.hash(this.passwordHash, 10);
  next();
});

// Confirm Password
UserSchema.methods.comparePassword = function(candidate) {
  return bcrypt.compare(candidate, this.passwordHash);
};

module.exports = mongoose.model('User', UserSchema);

// models/Product.js
const ProductSchema = new mongoose.Schema({
  sku: { type: String, required: true, unique: true, index: true },
  title: { type: String, required: true, maxlength: 200 },
  description: { type: String, maxlength: 5000 },
  price: { type: mongoose.Schema.Types.Decimal128, required: true, min: 0 },
  category: { type: String, enum: ['Electronics', 'Books', 'Clothing', 'Home'], index: true },
  stock: { type: Number, default: 0, min: 0 },
  rating: { type: Number, default: 0, min: 0, max: 5 },
  reviewCount: { type: Number, default: 0 },
  isActive: { type: Boolean, default: true, index: true }
}, { timestamps: true });

ProductSchema.index({ category: 1, price: -1 });
ProductSchema.index({ title: 'text', description: 'text' });

module.exports = mongoose.model('Product', ProductSchema);

// models/Review.js
const ReviewSchema = new mongoose.Schema({
  productId: { type: mongoose.Schema.Types.ObjectId, ref: 'Product', required: true, index: true },
  userId: { type: mongoose.Schema.Types.ObjectId, ref: 'User', required: true },
  content: { type: String, required: true, maxlength: 1000 },
  rating: { type: Number, required: true, min: 1, max: 5 },
  parentId: { type: mongoose.Schema.Types.ObjectId, ref: 'Review', default: null, index: true },
  likes: [{ type: mongoose.Schema.Types.ObjectId, ref: 'User' }],
  likeCount: { type: Number, default: 0 },
  isApproved: { type: Boolean, default: true },
  isDeleted: { type: Boolean, default: false }
}, { timestamps: true });

ReviewSchema.index({ productId: 1, createdAt: -1 });
ReviewSchema.pre(/^find/, function(next) {
  this.where({ isDeleted: { $ne: true } });
  next();
});

module.exports = mongoose.model('Review', ReviewSchema);

// controllers/reviewController.js
exports.createReview = async (req, res) => {
  const { productId } = req.params;
  const { content, rating, parentId } = req.body;

  // Verify that the product exists
  const product = await Product.findById(productId);
  if (!product) return res.status(404).json({ error: 'Product not found' });

  // If this is a reply, verify that the parent comment exists
  if (parentId) {
    const parent = await Review.findById(parentId);
    if (!parent) return res.status(404).json({ error: 'Parent review not found' });
  }

  const review = await Review.create({
    productId,
    userId: req.user._id,
    content,
    rating,
    parentId: parentId || null
  });

  // Update product rating statistics
  await updateProductRating(productId);

  await review.populate('userId', 'username avatar');
  res.status(201).json(review);
};

exports.listReviews = async (req, res) => {
  const { productId } = req.params;
  const { sort = 'createdAt', order = 'desc', limit = 20, page = 1 } = req.query;

  // Query top-level comments
  const reviews = await Review.find({
    productId,
    parentId: null
  })
    .populate('userId', 'username avatar')
    .sort({ [sort]: order === 'desc' ? -1 : 1 })
    .limit(limit * 1)
    .skip((page - 1) * limit)
    Continue

  // View all replies
  const reviewIds = reviews.map(r => r._id);
  const replies = await Review.find({
    parentId: { $in: reviewIds }
  })
    .populate('userId', 'username avatar')
    .sort({ createdAt: 1 })
    Continue

  // Build a tree structure
  const tree = reviews.map(parent => ({
    ...parent,
    replies: replies.filter(r => r.parentId.toString() === parent._id.toString())
  }));

  res.json({ data: tree, page, limit });
};

exports.likeReview = async (req, res) => {
  const { reviewId } = req.params;
  const userId = req.user._id;

  const review = await Review.findById(reviewId);
  if (!review) return res.status(404).json({ error: 'Review not found' });

  const alreadyLiked = review.likes.some(id => id.toString() === userId.toString());

  if (alreadyLiked) {
    await Review.updateOne(
      { _id: reviewId },
      { $pull: { likes: userId }, $inc: { likeCount: -1 } }
    );
    return res.json({ liked: false });
  } else {
    await Review.updateOne(
      { _id: reviewId },
      { $addToSet: { likes: userId }, $inc: { likeCount: 1 } }
    );
    return res.json({ liked: true });
  }
};

exports.getRatingDistribution = async (req, res) => {
  const { productId } = req.params;

  const distribution = await Review.aggregate([
    { $match: { productId: new mongoose.Types.ObjectId(productId), parentId: null } },
    {
      $bucket: {
        groupBy: '$rating',
        boundaries: [1, 2, 3, 4, 5, 6],
        default: 'Other',
        output: {
          count: { $sum: 1 },
          avgHelpful: { $avg: '$likeCount' }
        }
      }
    }
  ]);

  res.json({ data: distribution });
};

exports.getProductStats = async (req, res) => {
  const { productId } = req.params;

  const stats = await Review.aggregate([
    { $match: { productId: new mongoose.Types.ObjectId(productId), parentId: null } },
    {
      $facet: {
        total: [{ $count: 'count' }],
        avgRating: [{ $group: { _id: null, avg: { $avg: '$rating' } } }],
        ratingDistribution: [
          { $group: { _id: '$rating', count: { $sum: 1 } } },
          { $sort: { _id: 1 } }
        ],
        recentReviews: [
          { $sort: { createdAt: -1 } },
          { $limit: 5 },
          {
            $lookup: {
              from: 'users',
              localField: 'userId',
              foreignField: '_id',
              as: 'userInfo'
            }
          },
          { $unwind: '$userInfo' },
          {
            $project: {
              content: 1,
              rating: 1,
              createdAt: 1,
              username: '$userInfo.username',
              avatar: '$userInfo.avatar'
            }
          }
        ]
      }
    }
  ]);

  res.json(stats[0]);
};

exports.getTopProducts = async (req, res) => {
  const { limit = 10 } = req.query;

  const topProducts = await Review.aggregate([
    { $match: { parentId: null, isApproved: true } },
    {
      $group: {
        _id: '$productId',
        avgRating: { $avg: '$rating' },
        reviewCount: { $sum: 1 },
        totalLikes: { $sum: '$likeCount' }
      }
    },
    { $sort: { avgRating: -1, reviewCount: -1 } },
    { $limit: limit * 1 },
    {
      $lookup: {
        from: 'products',
        localField: '_id',
        foreignField: '_id',
        as: 'product'
      }
    },
    { $unwind: '$product' },
    {
      $project: {
        sku: '$product.sku',
        title: '$product.title',
        thumbnail: '$product.thumbnail',
        avgRating: 1,
        reviewCount: 1
      }
    }
  ]);

  res.json({ data: topProducts });
};

// middlewares/auth.js
const jwt = require('jsonwebtoken');

exports.authenticate = (req, res, next) => {
  const token = req.header('Authorization')?.replace('Bearer ', '');
  if (!token) return res.status(401).json({ error: 'No token' });

  try {
    const decoded = jwt.verify(token, process.env.JWT_SECRET);
    req.user = decoded;
    next();
  } catch (err) {
    res.status(401).json({ error: 'Invalid token' });
  }
};

exports.authorize = (...roles) => (req, res, next) => {
  if (!req.user || !roles.includes(req.user.role)) {
    return res.status(403).json({ error: 'Forbidden' });
  }
  next();
};

// controllers/authController.js
const User = require('../models/User');
const jwt = require('jsonwebtoken');

exports.register = async (req, res) => {
  const { email, username, password } = req.body;

  const existing = await User.findOne({ $or: [{ email }, { username }] });
  if (existing) return res.status(409).json({ error: 'Email or username already exists' });

  const user = await User.create({
    email,
    username,
    passwordHash: password  // pre-save The middleware performs hashing
  });

  const token = jwt.sign(
    { id: user._id, role: user.role },
    process.env.JWT_SECRET,
    { expiresIn: '7d' }
  );

  res.status(201).json({ user: { id: user._id, email: user.email, username: user.username }, token });
};

exports.login = async (req, res) => {
  const { email, password } = req.body;

  const user = await User.findOne({ email }).select('+passwordHash');
  if (!user) return res.status(401).json({ error: 'Invalid credentials' });

  const valid = await user.comparePassword(password);
  if (!valid) return res.status(401).json({ error: 'Invalid credentials' });

  const token = jwt.sign(
    { id: user._id, role: user.role },
    process.env.JWT_SECRET,
    { expiresIn: '7d' }
  );

  res.json({ user: { id: user._id, email: user.email, username: user.username, role: user.role }, token });
};

// ❌ Danger: $where executes arbitrary JavaScript
db.reviews.find({ $where: 'this.userId == "' + userId + '"' });

// ✅ Security: Use parameterized queries
db.reviews.find({ userId: new ObjectId(userId) });

// ✅ Mongoose auto-escapes
const reviews = await Review.find({ userId: userId });

// ❌ Danger: $regex DoS
db.reviews.find({ content: { $regex: req.query.q } });

// ✅ Security: Escape special characters in regular expressions
function escapeRegex(str) {
  return str.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
}
db.reviews.find({ content: { $regex: escapeRegex(req.query.q), $options: 'i' } });

# 1. Create Atlas Cluster(Recommended Courses #01)
# 2. Layout IP Whitelist:0.0.0.0/0(Development)or application server IP
# 3. Create a Database User:app_user / <password>
# 4. Get the connection string:
mongodb+srv://app_user:<password>@cluster0.mongodb.net/shophub?retryWrites=true&w=majority

# .env.production
NODE_ENV=production
PORT=3000
MONGODB_URI=mongodb+srv://app_user:StrongPass@cluster0.mongodb.net/shophub?retryWrites=true&w=majority
JWT_SECRET=<generated-strong-secret-256-bit>
JWT_EXPIRES_IN=7d
CORS_ORIGIN=https://shophub.example.com

app.get('/healthz', async (req, res) => {
  try {
    const db = mongoose.connection.db;
    await db.admin().command({ ping: 1 });
    res.json({
      status: 'ok',
      uptime: process.uptime(),
      mongo: 'connected',
      timestamp: new Date().toISOString()
    });
  } catch (err) {
    res.status(503).json({ status: 'error', error: err.message });
  }
});

# === Render Deployment ===
# 1. Connect GitHub Warehouse
# 2. Set Environment Variables (MONGODB_URI, JWT_SECRET, etc.)
# 3. Set Up Build Commands:npm install
# 4. Set the startup command:npm start
# 5. Automatic HTTPS + Deployment

# === Railway Deployment ===
railway login
railway init
railway add mongodb  # Add with One Click MongoDB
railway up

// === src/app.js Optimized Version ===
const mongoose = require('mongoose');

mongoose.connect(process.env.MONGODB_URI, {
  maxPoolSize: 50,
  minPoolSize: 5,
  serverSelectionTimeoutMS: 5000
});

app.use(express.json({ limit: '1mb' }));
app.use(cors({
  origin: process.env.CORS_ORIGIN || '*',
  credentials: true
}));

# === Launch the Project ===
npm install
npm start

# === API Usage Example ===

# 1. Registered Users
curl -X POST http://localhost:3000/api/auth/register \
  -H "Content-Type: application/json" \
  -d '{"email":"alice@example.com","username":"alice","password":"Pass123!"}'

# 2. Log In
curl -X POST http://localhost:3000/api/auth/login \
  -H "Content-Type: application/json" \
  -d '{"email":"alice@example.com","password":"Pass123!"}'

# 3. Create a Review
curl -X POST http://localhost:3000/api/products/<productId>/reviews \
  -H "Authorization: Bearer <token>" \
  -H "Content-Type: application/json" \
  -d '{"content":"Great product!","rating":5}'

# 4. View Product Statistics
curl http://localhost:3000/api/products/<productId>/stats

# 5. Health Checkup
curl http://localhost:3000/healthz

// === Scenario: Alice reviews a product, Bob replies to Alice, Charlie likes it ===

// 1. Alice Published 5 Star Reviews
const aliceReview = await Review.create({
  productId: '647f1f77bcf86cd799439011',
  userId: aliceId,
  content: 'Excellent smartphone! The camera quality is outstanding.',
  rating: 5,
  parentId: null  // Top Comments
});
// Back: { _id: 'review001', content: '...', rating: 5, likeCount: 0 }

// 2. Bob Reply Alice
const bobReply = await Review.create({
  productId: '647f1f77bcf86cd799439011',
  userId: bobId,
  content: 'I agree, the camera is amazing!',
  rating: 5,
  parentId: aliceReview._id  // Quote parent's comment
});
// Back: { _id: 'review002', parentId: 'review001', content: '...' }

// 3. Charlie likes Alice's comment
await Review.updateOne(
  { _id: aliceReview._id },
  { $addToSet: { likes: charlieId }, $inc: { likeCount: 1 } }
);
// Alice Comments on: { likeCount: 1, likes: [charlieId] }

// 4. Like again → Cancel
await Review.updateOne(
  { _id: aliceReview._id },
  { $pull: { likes: charlieId }, $inc: { likeCount: -1 } }
);
// Alice Comments on: { likeCount: 0, likes: [] }

// 5. Querying a Nested Comment Tree
const reviews = await Review.find({ productId: '647f...', parentId: null })
  .populate('userId', 'username avatar')
  .lean();
const replies = await Review.find({ parentId: { $in: reviews.map(r => r._id) } })
  .populate('userId', 'username avatar')
  .lean();
const tree = reviews.map(r => ({
  ...r,
  replies: replies.filter(rep => rep.parentId.toString() === r._id.toString())
}));

console.log(JSON.stringify(tree, null, 2));
// [{
//   content: 'Excellent smartphone!...',
//   userId: { username: 'alice', avatar: '...' },
//   replies: [{ content: 'I agree...', userId: { username: 'bob' } }]
// }]

# === 1. Start MongoDB Dungeon Collection ===
docker run -d --name mongo -p 27017:27017 mongo:7.0 --replSet rs0
docker exec mongo mongosh --eval 'rs.initiate()'

# === 2. Start Node.js Applications ===
npm install
npm start

# Output:
# ✅ MongoDB connected: localhost
# 🚀 Server running on port 3000

# === 3. Test Core API ===

# 3.1 User Registration
curl -X POST http://localhost:3000/api/auth/register \
  -H "Content-Type: application/json" \
  -d '{"email":"alice@example.com","username":"alice","password":"Pass123!"}'

# Back:
# {
#   "success": true,
#   "user": { "id": "...", "email": "alice@example.com", "username": "alice" },
#   "token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9..."
# }

# 3.2 User Login
curl -X POST http://localhost:3000/api/auth/login \
  -H "Content-Type: application/json" \
  -d '{"email":"alice@example.com","password":"Pass123!"}'

# 3.3 Create a Product
curl -X POST http://localhost:3000/api/products \
  -H "Authorization: Bearer <admin_token>" \
  -H "Content-Type: application/json" \
  -d '{
    "sku": "PHONE-001",
    "title": "Smartphone X",
    "price": 599,
    "category": "Electronics",
    "stock": 50
  }'

# 3.4 Product List(With pagination + Projection)
curl 'http://localhost:3000/api/products?page=1&limit=20&category=Electronics'

# Back:
# {
#   "success": true,
#   "data": [{ "sku": "PHONE-001", "title": "Smartphone X", "price": 599, "thumbnail": "...", "rating": 0 }],
#   "meta": { "page": 1, "limit": 20, "total": 1, "pages": 1 }
# }

# 3.5 Add a comment
curl -X POST http://localhost:3000/api/products/507f1f77bcf86cd799439021/reviews \
  -H "Authorization: Bearer <user_token>" \
  -H "Content-Type: application/json" \
  -d '{"content":"Great phone!","rating":5}'

# 3.6 Like and Comment
curl -X POST http://localhost:3000/api/reviews/507f1f77bcf86cd799439031/like \
  -H "Authorization: Bearer <user_token>"

# 3.7 View Product Statistics
curl http://localhost:3000/api/products/507f1f77bcf86cd799439021/stats

# Back:
# {
#   "total": [{ "count": 1 }],
#   "avgRating": [{ "avg": 5 }],
#   "ratingDistribution": [{ "_id": 5, "count": 1 }],
#   "recentReviews": [{ "content": "Great phone!", "rating": 5, "username": "alice" }]
# }

# 3.8 Health Checkup
curl http://localhost:3000/healthz

# Back:
# {
#   "status": "ok",
#   "uptime": 1234,
#   "mongo": "connected",
#   "timestamp": "2026-07-06T10:00:00.000Z"
# }

# === 4. Deploy to Render/Railway ===
git push heroku main
# Automatic Deployment，Environment Variables MONGODB_URI Orientation Atlas

# === 5. Performance Monitoring(Production)===
# Datadog APM Automatic Tracking:
# - mongoose Query Duration
# - API Response Time
# - Number of database connections
# - Slow Query Alerts