Library Management System - Backend API

A full-fledged CRUD backend application built with Node.js, Express, and MongoDB (Mongoose) following clean OOP architecture principles.

Architecture

The application follows a clean layered architecture:

controllers → services → repositories → models

Each layer is implemented using ES6 classes:

• Controllers: Handle HTTP requests and responses only
• Services: Contain business logic only
• Repositories: Contain database logic only
• Models: Define data schemas using Mongoose

Project Structure

workshop-sesd/
├── src/
│   ├── config/
│   │   ├── database.js       # MongoDB connection
│   │   └── jwt.js            # JWT configuration
│   ├── models/
│   │   ├── Book.js
│   │   ├── Author.js
│   │   ├── Member.js
│   │   └── Borrowing.js
│   ├── repositories/
│   │   ├── BaseRepository.js
│   │   ├── BookRepository.js
│   │   ├── AuthorRepository.js
│   │   ├── MemberRepository.js
│   │   └── BorrowingRepository.js
│   ├── services/
│   │   ├── BookService.js
│   │   ├── AuthorService.js
│   │   ├── MemberService.js
│   │   └── BorrowingService.js
│   ├── controllers/
│   │   ├── BookController.js
│   │   ├── AuthorController.js
│   │   ├── MemberController.js
│   │   └── BorrowingController.js
│   ├── routes/
│   │   ├── bookRoutes.js
│   │   ├── authorRoutes.js
│   │   ├── memberRoutes.js
│   │   └── borrowingRoutes.js
│   ├── middleware/
│   │   ├── errorHandler.js   # Centralized error handling
│   │   ├── auth.js           # JWT authentication & authorization
│   │   └── validator.js      # Input validation
│   └── utils/
│       └── errors.js          # Custom error class
├── app.js                     # Express app configuration
├── server.js                  # Server entry point
├── package.json
└── README.md

Features

Core CRUD Operations

• ✅ Create entity
• ✅ Get entity by ID
• ✅ Get list of entities
• ✅ Update entity
• ✅ Delete entity

Advanced Features

• ✅ Search: Case-insensitive text search across multiple fields
• ✅ Filtering: Filter by specific fields (genre, status, etc.)
• ✅ Sorting: Sort by any field (asc/desc)
• ✅ Pagination: Page and limit parameters
• ✅ Input Validation: Comprehensive validation using express-validator
• ✅ Centralized Error Handling: Custom error handling middleware

Bonus Features

• ✅ JWT Authentication: Secure token-based authentication
• ✅ Role-based Authorization: Different access levels (member, librarian, admin)

Entities

Book

• Title, ISBN, Author, Genre, Published Year
• Total copies and available copies tracking
• Description, Publisher, Language

Author

• First name, Last name, Email
• Bio, Nationality, Date of birth
• Active status

Member

• First name, Last name, Email, Password
• Phone, Address, Membership type
• Role (member, librarian, admin)
• Max borrow limit

Borrowing

• Book, Member, Borrow date, Due date
• Return date, Status (borrowed/returned/overdue)
• Fine amount calculation
• Automatic status updates

Installation

1. Install dependencies:

npm install

2. Create a .env file in the root directory:

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

3. Make sure MongoDB is running on your system

4. Start the server:

npm start

For development with auto-reload:

npm run dev

API Endpoints

Books

• GET /api/v1/books - Get all books (with search, filter, sort, pagination)
• GET /api/v1/books/available - Get available books
• GET /api/v1/books/:id - Get book by ID
• POST /api/v1/books - Create book (librarian/admin only)
• PATCH /api/v1/books/:id - Update book (librarian/admin only)
• DELETE /api/v1/books/:id - Delete book (admin only)

Authors

• GET /api/v1/authors - Get all authors
• GET /api/v1/authors/active - Get active authors
• GET /api/v1/authors/:id - Get author by ID
• POST /api/v1/authors - Create author (librarian/admin only)
• PATCH /api/v1/authors/:id - Update author (librarian/admin only)
• DELETE /api/v1/authors/:id - Delete author (admin only)

Members

• POST /api/v1/members/register - Register new member
• POST /api/v1/members/login - Login member
• GET /api/v1/members - Get all members (librarian/admin only)
• GET /api/v1/members/active - Get active members (librarian/admin only)
• GET /api/v1/members/:id - Get member by ID (authenticated)
• PATCH /api/v1/members/:id - Update member (authenticated)
• DELETE /api/v1/members/:id - Delete member (admin only)

Borrowings

• GET /api/v1/borrowings - Get all borrowings (librarian/admin only)
• GET /api/v1/borrowings/active - Get active borrowings
• GET /api/v1/borrowings/overdue - Get overdue borrowings
• GET /api/v1/borrowings/member/:memberId - Get borrowings by member
• GET /api/v1/borrowings/book/:bookId - Get borrowings by book
• GET /api/v1/borrowings/:id - Get borrowing by ID
• POST /api/v1/borrowings - Create borrowing (librarian/admin only)
• PATCH /api/v1/borrowings/:id - Update borrowing (librarian/admin only)
• PATCH /api/v1/borrowings/:id/return - Return book (librarian/admin only)
• DELETE /api/v1/borrowings/:id - Delete borrowing (admin only)

Query Parameters

Search

• ?search=keyword - Search across relevant fields (case-insensitive)

Filtering

• ?genre=Fiction - Filter by genre
• ?status=borrowed - Filter by status
• ?isActive=true - Filter by active status
• ?author=<authorId> - Filter by author
• ?member=<memberId> - Filter by member

Sorting

• ?sort=title - Sort ascending by title
• ?sort=-createdAt - Sort descending by creation date
• ?sort=publishedYear,-title - Multiple sort fields

Pagination

• ?page=1 - Page number (default: 1)
• ?limit=10 - Items per page (default: 10, max: 100)

Example

GET /api/v1/books?search=harry&genre=Fiction&sort=-publishedYear&page=1&limit=20

Authentication

Most endpoints require authentication. Include the JWT token in the Authorization header:

Authorization: Bearer <your-jwt-token>

Register

POST /api/v1/members/register
{
  "firstName": "John",
  "lastName": "Doe",
  "email": "john@example.com",
  "password": "password123"
}

Login

POST /api/v1/members/login
{
  "email": "john@example.com",
  "password": "password123"
}

Response includes a JWT token:

{
  "status": "success",
  "data": {
    "member": { ... },
    "token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9..."
  }
}

Error Handling

The API uses centralized error handling with consistent error responses:

{
  "status": "error",
  "message": "Error message here"
}

Technologies Used

• Node.js - Runtime environment
• Express - Web framework
• MongoDB - Database
• Mongoose - ODM
• JWT - Authentication
• bcryptjs - Password hashing
• express-validator - Input validation
• dotenv - Environment variables

Best Practices

• ✅ Clean separation of concerns
• ✅ ES6 classes for all layers
• ✅ Async/await throughout
• ✅ Comprehensive error handling
• ✅ Input validation
• ✅ Security best practices (password hashing, JWT)
• ✅ Database indexing for performance
• ✅ Virtual fields for computed properties
• ✅ Pre-save hooks for data transformation

License

ISC

sesd