Lesson 10: Mini Project Simple Blog API

🎯 Learning Objectives

By the end of this lesson, you will be able to:

Build a complete blog API with Express.js
Implement user authentication and authorization
Create CRUD operations for posts and comments
Handle file uploads for images
Implement data validation and error handling
Deploy the API to production

📚 Project Overview

We'll build a comprehensive blog API that includes: - User registration and authentication - Post creation, editing, and deletion - Comment system - Image uploads - Data validation and error handling - MongoDB integration

🏗️ Project Structure

blog-api/
├── package.json
├── .env
├── server.js
├── models/
│   ├── User.js
│   ├── Post.js
│   └── Comment.js
├── routes/
│   ├── auth.js
│   ├── posts.js
│   └── comments.js
├── middleware/
│   ├── auth.js
│   └── errorHandler.js
└── uploads/

📝 Package.json

{
  "name": "blog-api",
  "version": "1.0.0",
  "description": "A simple blog API with authentication",
  "main": "server.js",
  "scripts": {
    "start": "node server.js",
    "dev": "nodemon server.js",
    "test": "jest"
  },
  "dependencies": {
    "express": "^4.18.0",
    "mongoose": "^6.0.0",
    "bcryptjs": "^2.4.3",
    "jsonwebtoken": "^9.0.0",
    "multer": "^1.4.5",
    "cors": "^2.8.5",
    "helmet": "^6.0.0",
    "morgan": "^1.10.0",
    "dotenv": "^16.0.0",
    "express-validator": "^6.14.0"
  },
  "devDependencies": {
    "nodemon": "^2.0.0",
    "jest": "^29.0.0"
  }
}

💻 Complete Implementation

Server.js

const express = require('express');
const mongoose = require('mongoose');
const cors = require('cors');
const helmet = require('helmet');
const morgan = require('morgan');
const path = require('path');
require('dotenv').config();

const app = express();

// Middleware
app.use(helmet());
app.use(cors());
app.use(morgan('combined'));
app.use(express.json({ limit: '10mb' }));
app.use(express.urlencoded({ extended: true }));
app.use('/uploads', express.static(path.join(__dirname, 'uploads')));

// Database connection
mongoose.connect(process.env.MONGODB_URI || 'mongodb://localhost:27017/blog-api', {
    useNewUrlParser: true,
    useUnifiedTopology: true
});

const db = mongoose.connection;
db.on('error', console.error.bind(console, 'MongoDB connection error:'));
db.once('open', () => {
    console.log('Connected to MongoDB');
});

// Routes
app.use('/api/auth', require('./routes/auth'));
app.use('/api/posts', require('./routes/posts'));
app.use('/api/comments', require('./routes/comments'));

// Error handling middleware
app.use(require('./middleware/errorHandler'));

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

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

Models/User.js

const mongoose = require('mongoose');
const bcrypt = require('bcryptjs');

const userSchema = new mongoose.Schema({
    name: {
        type: String,
        required: [true, 'Name is required'],
        trim: true,
        maxlength: [50, 'Name cannot exceed 50 characters']
    },
    email: {
        type: String,
        required: [true, 'Email is required'],
        unique: true,
        lowercase: true,
        match: [/^\w+([.-]?\w+)*@\w+([.-]?\w+)*(\.\w{2,3})+$/, 'Please enter a valid email']
    },
    password: {
        type: String,
        required: [true, 'Password is required'],
        minlength: [6, 'Password must be at least 6 characters']
    },
    avatar: {
        type: String,
        default: ''
    },
    role: {
        type: String,
        enum: ['user', 'admin'],
        default: 'user'
    }
}, {
    timestamps: true
});

// Hash password before saving
userSchema.pre('save', async function(next) {
    if (!this.isModified('password')) return next();
    this.password = await bcrypt.hash(this.password, 12);
    next();
});

// Compare password method
userSchema.methods.comparePassword = async function(candidatePassword) {
    return await bcrypt.compare(candidatePassword, this.password);
};

// Remove password from JSON output
userSchema.methods.toJSON = function() {
    const user = this.toObject();
    delete user.password;
    return user;
};

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

Models/Post.js

const mongoose = require('mongoose');

const postSchema = new mongoose.Schema({
    title: {
        type: String,
        required: [true, 'Title is required'],
        trim: true,
        maxlength: [100, 'Title cannot exceed 100 characters']
    },
    content: {
        type: String,
        required: [true, 'Content is required'],
        minlength: [10, 'Content must be at least 10 characters']
    },
    excerpt: {
        type: String,
        maxlength: [200, 'Excerpt cannot exceed 200 characters']
    },
    image: {
        type: String,
        default: ''
    },
    author: {
        type: mongoose.Schema.Types.ObjectId,
        ref: 'User',
        required: true
    },
    tags: [{
        type: String,
        trim: true
    }],
    published: {
        type: Boolean,
        default: false
    },
    publishedAt: {
        type: Date
    },
    views: {
        type: Number,
        default: 0
    }
}, {
    timestamps: true
});

// Generate excerpt from content
postSchema.pre('save', function(next) {
    if (this.isModified('content') && !this.excerpt) {
        this.excerpt = this.content.substring(0, 200) + '...';
    }
    next();
});

// Increment views
postSchema.methods.incrementViews = function() {
    this.views += 1;
    return this.save();
};

module.exports = mongoose.model('Post', postSchema);

Routes/auth.js

const express = require('express');
const jwt = require('jsonwebtoken');
const { body, validationResult } = require('express-validator');
const User = require('../models/User');
const auth = require('../middleware/auth');

const router = express.Router();

// Generate JWT token
const generateToken = (userId) => {
    return jwt.sign({ userId }, process.env.JWT_SECRET, { expiresIn: '7d' });
};

// Register
router.post('/register', [
    body('name').trim().isLength({ min: 2, max: 50 }).withMessage('Name must be 2-50 characters'),
    body('email').isEmail().normalizeEmail().withMessage('Please provide a valid email'),
    body('password').isLength({ min: 6 }).withMessage('Password must be at least 6 characters')
], async (req, res) => {
    try {
        const errors = validationResult(req);
        if (!errors.isEmpty()) {
            return res.status(400).json({
                success: false,
                errors: errors.array()
            });
        }

        const { name, email, password } = req.body;

        // Check if user exists
        const existingUser = await User.findOne({ email });
        if (existingUser) {
            return res.status(400).json({
                success: false,
                message: 'User already exists'
            });
        }

        // Create user
        const user = new User({ name, email, password });
        await user.save();

        const token = generateToken(user._id);

        res.status(201).json({
            success: true,
            message: 'User registered successfully',
            token,
            user
        });
    } catch (error) {
        res.status(500).json({
            success: false,
            message: 'Server error',
            error: error.message
        });
    }
});

// Login
router.post('/login', [
    body('email').isEmail().normalizeEmail().withMessage('Please provide a valid email'),
    body('password').notEmpty().withMessage('Password is required')
], async (req, res) => {
    try {
        const errors = validationResult(req);
        if (!errors.isEmpty()) {
            return res.status(400).json({
                success: false,
                errors: errors.array()
            });
        }

        const { email, password } = req.body;

        // Find user
        const user = await User.findOne({ email });
        if (!user) {
            return res.status(401).json({
                success: false,
                message: 'Invalid credentials'
            });
        }

        // Check password
        const isMatch = await user.comparePassword(password);
        if (!isMatch) {
            return res.status(401).json({
                success: false,
                message: 'Invalid credentials'
            });
        }

        const token = generateToken(user._id);

        res.json({
            success: true,
            message: 'Login successful',
            token,
            user
        });
    } catch (error) {
        res.status(500).json({
            success: false,
            message: 'Server error',
            error: error.message
        });
    }
});

// Get current user
router.get('/me', auth, async (req, res) => {
    try {
        const user = await User.findById(req.user.userId);
        res.json({
            success: true,
            user
        });
    } catch (error) {
        res.status(500).json({
            success: false,
            message: 'Server error',
            error: error.message
        });
    }
});

module.exports = router;

🎯 Key Features Implemented

User Authentication - Registration, login, JWT tokens
Post Management - CRUD operations for blog posts
Comment System - Nested comments on posts
Image Uploads - Multer for handling file uploads
Data Validation - Express-validator for input validation
Error Handling - Comprehensive error management
Security - Helmet, CORS, password hashing
Database - MongoDB with Mongoose ODM

🎯 Key Takeaways

Full-stack development with Node.js and Express
Authentication with JWT and bcrypt
Database design with Mongoose schemas
API design following REST principles
Security best practices for production
Error handling for robust applications

🚀 Next Steps

Congratulations! You've completed Module 6. You now understand:

Node.js fundamentals and server creation
Package management with npm
Express.js framework and middleware
REST API design and routing
File handling and uploads
Database integration with MongoDB
JWT authentication and security
Error handling and validation
Building complete backend applications

Ready for Module 7: Frontend Frameworks! 🎉

Next Module: Module 7: Frontend Frameworks

Lesson 10: Mini Project Simple Blog API

🎯 Learning Objectives

📚 Project Overview

🏗️ Project Structure

📝 Package.json

💻 Complete Implementation

Server.js

Models/User.js

Models/Post.js

Routes/auth.js

🎯 Key Features Implemented

🎯 Key Takeaways

🚀 Next Steps

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