📚 Library Management System – Backend (C# .NET API)

A lightweight and efficient RESTful API backend built using ASP.NET Core and Entity Framework Core with SQLite, designed to support a Library Management System.

This backend handles:

• 📚 Book CRUD operations
• 🔐 User Authentication (JWT-based)
• 🗄 SQLite database with Entity Framework
• 🌐 API endpoints for frontend integration

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🚀 Features

📘 Book Management (CRUD)

• Create new books
• Retrieve all books
• Retrieve book by ID
• Update book details
• Delete a book

🔐 User Authentication (Optional Feature)

• Register new users
• Login with username & password
• JWT authentication
• Secure password hashing (BCrypt)

🛠 Technical Capabilities

• ASP.NET Core Web API
• Entity Framework Core
• SQLite Integration
• Layered folder structure
• DTO models for input validation

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📦 Project Structure

Library Management System/
├── Controllers/
│   ├── AuthController.cs           # User Register/Login
│   ├── BookController.cs           # CRUD endpoints for books
│   └── WeatherForecastController.cs  # Default sample
│
├── Data/
│   └── AppDbContext.cs             # EF Core DB Context
│
├── Migrations/                     # Auto-generated EF Migrations
│
├── Models/
│   ├── AddBookDto.cs               # DTO for adding books
│   ├── UpdateBookDto.cs            # DTO for updating books
│   ├── UserDto.cs                  # DTO for user authentication
│   ├── Book.cs                     # Book model
│   └── User.cs                     # User model
│
├── library.db                      # SQLite database
├── appsettings.json                # DB + JWT Config
├── Program.cs                      # API configuration
└── README.md

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⚙️ Technologies Used

Layer	Technology
Backend Framework	ASP.NET Core Web API
Database	SQLite
ORM	Entity Framework Core
Authentication	JWT (JSON Web Tokens)
Password Hashing	BCrypt.Net
Language	C#
Tooling	.NET 8

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🔧 API Endpoints

📚 Books API

Method	Endpoint	Description
GET	/api/books	Get all books
GET	/api/books/{id}	Get book by ID
POST	/api/books	Add a new book
PUT	/api/books/{id}	Update a book
DELETE	/api/books/{id}	Delete a book

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🔐 Authentication API

Method	Endpoint	Description
POST	/api/auth/register	Register a new user
POST	/api/auth/login	Login user + return JWT token

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🗄 Database

SQLite database file is auto-generated:

library.db
library.db-shm
library.db-wal

EF Core handles migrations.

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🚀 Getting Started

1️⃣ Install Dependencies

Make sure you have:

• .NET 8 SDK
• SQLite installed (optional)

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2️⃣ Update Database Connection (optional)

In appsettings.json:

"ConnectionStrings": {
  "DefaultConnection": "Data Source=library.db"
}

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3️⃣ Apply Migrations

dotnet ef database update

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4️⃣ Run the API

dotnet run

Backend will run on:

https://localhost:7036
http://localhost:5239

(Ports may vary based on your system)

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🔐 Authentication Flow

Registration

User provides:

• username
• password

Password is hashed using BCrypt.

Login

• Validate password
• Generate JWT token
• Frontend stores token in localStorage

Protect Endpoints (Optional)

You can protect routes using:

[Authorize]

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📄 Environment Variables (JWT Config)

Inside appsettings.json:

"Jwt": {
  "Key": "YOUR_SECRET_KEY_HERE",
  "Issuer": "library-api",
  "Audience": "library-api"
}

Use a long, secure key for real apps.

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🧪 Testing the API

You can use:

• Postman
• Thunder Client (VS Code)
• Swagger UI (built-in)

Swagger loads automatically at:

https://localhost:7036/swagger

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🎓 Developer Notes

• Code follows clean architecture principles
• DTOs used for safety and input validation
• Controllers separated for maintainability
• Easy to integrate with any frontend (React, Vue, Angular)

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📜 License

MIT License – Free to use, modify, and distribute.

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👏 Acknowledgements

• Microsoft ASP.NET Core Team
• Entity Framework Core
• BCrypt.Net
• SQLite Development Team