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CRUD Operations with Express Routes · learncode.live

RESTful CRUD Mapping

CRUD operations map directly to HTTP methods and routes:

OperationHTTP MethodRouteStatus Code
CreatePOST/api/resource201 Created
Read (list)GET/api/resource200 OK
Read (single)GET/api/resource/:id200 OK
Update (full)PUT/api/resource/:id200 OK
Update (partial)PATCH/api/resource/:id200 OK
DeleteDELETE/api/resource/:id204 No Content

Project Structure

project/
├── models/
│   ├── User.js        # User model/schema
│   └── Product.js     # Product model/schema
├── routes/
│   ├── users.js       # User CRUD routes
│   └── products.js    # Product CRUD routes
├── middleware/
│   └── validate.js    # Validation middleware
├── index.js           # Entry point
└── package.json

Complete CRUD Example with Mongoose

Model (models/Product.js)

const mongoose = require('mongoose');

const productSchema = new mongoose.Schema({
  name: {
    type: String,
    required: [true, 'Product name is required'],
    trim: true
  },
  price: {
    type: Number,
    required: [true, 'Price is required'],
    min: [0, 'Price cannot be negative']
  },
  description: {
    type: String,
    maxlength: [1000, 'Description too long']
  },
  category: {
    type: String,
    required: true,
    enum: ['electronics', 'clothing', 'food', 'books']
  },
  inStock: {
    type: Boolean,
    default: true
  },
  quantity: {
    type: Number,
    default: 0,
    min: 0
  },
  tags: [String],
  createdAt: {
    type: Date,
    default: Date.now
  }
});

productSchema.index({ name: 'text', description: 'text' });

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

Router (routes/products.js)

const express = require('express');
const router = express.Router();
const Product = require('../models/Product');

// CREATE - POST /api/products
router.post('/', async (req, res, next) => {
  try {
    const product = await Product.create(req.body);
    res.status(201).json({
      success: true,
      data: product
    });
  } catch (err) {
    next(err);
  }
});

// READ (all) - GET /api/products
router.get('/', async (req, res, next) => {
  try {
    const { category, minPrice, maxPrice, inStock, sort, page, limit } = req.query;

    // Build filter
    const filter = {};
    if (category) filter.category = category;
    if (inStock !== undefined) filter.inStock = inStock === 'true';
    if (minPrice || maxPrice) {
      filter.price = {};
      if (minPrice) filter.price.$gte = parseFloat(minPrice);
      if (maxPrice) filter.price.$lte = parseFloat(maxPrice);
    }

    // Build sort
    let sortOption = { createdAt: -1 };
    if (sort) {
      const validSorts = ['price', '-price', 'name', '-name', 'createdAt', '-createdAt'];
      if (validSorts.includes(sort)) {
        const field = sort.replace('-', '');
        sortOption = { [field]: sort.startsWith('-') ? -1 : 1 };
      }
    }

    // Pagination
    const pageNum = Math.max(1, parseInt(page) || 1);
    const limitNum = Math.min(100, Math.max(1, parseInt(limit) || 10));
    const skip = (pageNum - 1) * limitNum;

    const [products, total] = await Promise.all([
      Product.find(filter)
        .sort(sortOption)
        .skip(skip)
        .limit(limitNum)
        .select('-__v'),
      Product.countDocuments(filter)
    ]);

    res.json({
      success: true,
      count: products.length,
      pagination: {
        page: pageNum,
        limit: limitNum,
        total,
        totalPages: Math.ceil(total / limitNum)
      },
      data: products
    });
  } catch (err) {
    next(err);
  }
});

// READ (single) - GET /api/products/:id
router.get('/:id', async (req, res, next) => {
  try {
    const product = await Product.findById(req.params.id).select('-__v');

    if (!product) {
      return res.status(404).json({
        success: false,
        error: 'Product not found'
      });
    }

    res.json({
      success: true,
      data: product
    });
  } catch (err) {
    next(err);
  }
});

// UPDATE (full) - PUT /api/products/:id
router.put('/:id', async (req, res, next) => {
  try {
    const product = await Product.findByIdAndUpdate(
      req.params.id,
      req.body,
      { new: true, runValidators: true }
    ).select('-__v');

    if (!product) {
      return res.status(404).json({
        success: false,
        error: 'Product not found'
      });
    }

    res.json({
      success: true,
      data: product
    });
  } catch (err) {
    next(err);
  }
});

// UPDATE (partial) - PATCH /api/products/:id
router.patch('/:id', async (req, res, next) => {
  try {
    // Only update provided fields
    const updates = {};
    const allowedFields = ['name', 'price', 'description', 'category', 'inStock', 'quantity', 'tags'];
    for (const [key, value] of Object.entries(req.body)) {
      if (allowedFields.includes(key)) {
        updates[key] = value;
      }
    }

    const product = await Product.findByIdAndUpdate(
      req.params.id,
      { $set: updates },
      { new: true, runValidators: true }
    ).select('-__v');

    if (!product) {
      return res.status(404).json({
        success: false,
        error: 'Product not found'
      });
    }

    res.json({
      success: true,
      data: product
    });
  } catch (err) {
    next(err);
  }
});

// DELETE - DELETE /api/products/:id
router.delete('/:id', async (req, res, next) => {
  try {
    const product = await Product.findByIdAndDelete(req.params.id);

    if (!product) {
      return res.status(404).json({
        success: false,
        error: 'Product not found'
      });
    }

    res.status(204).send();
  } catch (err) {
    next(err);
  }
});

module.exports = router;

Main App (index.js)

const express = require('express');
const mongoose = require('mongoose');

const app = express();

app.use(express.json());

// Routes
app.use('/api/products', require('./routes/products'));
app.use('/api/users', require('./routes/users'));

// 404 handler
app.use((req, res) => {
  res.status(404).json({ success: false, error: 'Route not found' });
});

// Global error handler
app.use((err, req, res, next) => {
  console.error(err);

  if (err.name === 'ValidationError') {
    const messages = Object.values(err.errors).map(e => e.message);
    return res.status(422).json({ success: false, error: 'Validation failed', details: messages });
  }

  if (err.name === 'CastError') {
    return res.status(400).json({ success: false, error: 'Invalid ID format' });
  }

  if (err.code === 11000) {
    return res.status(409).json({ success: false, error: 'Duplicate key' });
  }

  res.status(500).json({ success: false, error: 'Internal server error' });
});

mongoose.connect(process.env.MONGO_URI)
  .then(() => app.listen(3000))
  .catch(err => console.error(err));

CRUD with Prisma (for comparison)

// routes/products.js (Prisma version)
const express = require('express');
const router = express.Router();
const prisma = require('../config/prisma');

router.post('/', async (req, res, next) => {
  try {
    const product = await prisma.product.create({ data: req.body });
    res.status(201).json({ success: true, data: product });
  } catch (err) { next(err); }
});

router.get('/', async (req, res, next) => {
  try {
    const { category, page = 1, limit = 10 } = req.query;
    const where = category ? { category } : {};

    const [products, total] = await Promise.all([
      prisma.product.findMany({
        where,
        skip: (parseInt(page) - 1) * parseInt(limit),
        take: parseInt(limit),
        orderBy: { createdAt: 'desc' }
      }),
      prisma.product.count({ where })
    ]);

    res.json({
      success: true,
      count: products.length,
      pagination: { page: parseInt(page), limit: parseInt(limit), total },
      data: products
    });
  } catch (err) { next(err); }
});

router.get('/:id', async (req, res, next) => {
  try {
    const product = await prisma.product.findUnique({ where: { id: req.params.id } });
    if (!product) return res.status(404).json({ success: false, error: 'Not found' });
    res.json({ success: true, data: product });
  } catch (err) { next(err); }
});

router.put('/:id', async (req, res, next) => {
  try {
    const product = await prisma.product.update({
      where: { id: req.params.id },
      data: req.body
    });
    res.json({ success: true, data: product });
  } catch (err) {
    if (err.code === 'P2025') {
      return res.status(404).json({ success: false, error: 'Not found' });
    }
    next(err);
  }
});

router.delete('/:id', async (req, res, next) => {
  try {
    await prisma.product.delete({ where: { id: req.params.id } });
    res.status(204).send();
  } catch (err) {
    if (err.code === 'P2025') {
      return res.status(404).json({ success: false, error: 'Not found' });
    }
    next(err);
  }
});

module.exports = router;

Testing CRUD with cURL

# CREATE
curl -X POST http://localhost:3000/api/products \
  -H "Content-Type: application/json" \
  -d '{"name":"Wireless Mouse","price":29.99,"category":"electronics","quantity":50}'

# READ all
curl http://localhost:3000/api/products

# READ all with filters
curl "http://localhost:3000/api/products?category=electronics&minPrice=10&maxPrice=100&sort=-price&page=1&limit=5"

# READ single
curl http://localhost:3000/api/products/507f1f77bcf86cd799439011

# UPDATE full
curl -X PUT http://localhost:3000/api/products/507f1f77bcf86cd799439011 \
  -H "Content-Type: application/json" \
  -d '{"name":"Wireless Mouse Pro","price":49.99,"category":"electronics","quantity":30}'

# UPDATE partial
curl -X PATCH http://localhost:3000/api/products/507f1f77bcf86cd799439011 \
  -H "Content-Type: application/json" \
  -d '{"price":39.99}'

# DELETE
curl -X DELETE http://localhost:3000/api/products/507f1f77bcf86cd799439011

Consistent Response Format

// helpers/response.js
function sendSuccess(res, data, statusCode = 200) {
  res.status(statusCode).json({ success: true, data });
}

function sendError(res, message, statusCode = 500) {
  res.status(statusCode).json({ success: false, error: message });
}

function sendPaginated(res, data, pagination, statusCode = 200) {
  res.status(statusCode).json({
    success: true,
    count: data.length,
    pagination,
    data
  });
}

module.exports = { sendSuccess, sendError, sendPaginated };

Key Takeaways

  • Map POST → Create (201), GET → Read (200), PUT/PATCH → Update (200), DELETE → Delete (204)
  • Always validate input before database operations
  • Support filtering, sorting, and pagination via query parameters
  • Return consistent JSON responses with success and data / error fields
  • Handle database errors gracefully (validation, duplicate key, invalid ID)
  • Use try/catch or async middleware wrapper for all async routes
  • Place 404 handler and error handler after all routes
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