Library Management System API

A RESTful Web API built with ASP.NET Core (.NET 8) that allows users to manage books, members, and loans in a library system. The API supports full CRUD operations, uses Entity Framework Core with SQLite for data persistence, and is secured with JWT authentication.

This project demonstrates backend development with modern .NET technologies, clean API design, a layered service architecture, and a full test suite.

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Tech Stack

Backend

• C#
• ASP.NET Core Web API (.NET 8)
• Entity Framework Core
• SQLite

Security

• JWT Bearer Authentication
• BCrypt password hashing

Testing

• xUnit
• WebApplicationFactory (integration tests)
• In-memory database (unit tests)

Tools

• Swagger / OpenAPI (with JWT Bearer support)
• .NET CLI

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Features

Books

• Full CRUD — create, retrieve, update, and delete books
• Input validation using Data Annotations

Members

• Full CRUD — create, retrieve, update, and delete library members
• Email uniqueness validation
• Layered architecture — Controller → Service → Database
• Structured error handling via ServiceResult<T>

Loans

• Borrow a book — enforces availability and membership rules
• Return a book — updates availability automatically
• Maximum 3 active loans per member
• Full loan history per member

Authentication

• Register and login with email and password
• JWT Bearer tokens protect all API endpoints
• Passwords hashed with BCrypt

Tests

• 42 tests — unit and integration
• Unit tests cover all service business rules
• Integration tests cover all API endpoints end-to-end

General

• Swagger UI with JWT Bearer support

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Project Structure

LibraryManagement.Api
│
├── Controllers
│   ├── AuthController.cs
│   ├── BooksController.cs
│   ├── MembersController.cs
│   └── LoansController.cs
│
├── Data
│   └── LibraryDbContext.cs
│
├── DTOs
│   ├── Books
│   │   ├── CreateBookRequest.cs
│   │   ├── UpdateBookRequest.cs
│   │   └── BookResponse.cs
│   ├── Members
│   │   ├── CreateMemberRequest.cs
│   │   ├── UpdateMemberRequest.cs
│   │   └── MemberResponse.cs
│   ├── Auth
│   │   ├── RegisterRequest.cs
│   │   ├── LoginRequest.cs
│   │   └── AuthResponse.cs
│   └── Loans
│       ├── CreateLoanRequest.cs
│       └── LoanResponse.cs
│
├── Models
│   ├── Book.cs
│   ├── Member.cs
│   ├── Loan.cs
│   └── User.cs
│
├── Services
│   ├── ServiceResult.cs
│   ├── IAuthService.cs
│   ├── AuthService.cs
│   ├── IBookService.cs
│   ├── BookService.cs
│   ├── IMemberService.cs
│   ├── MemberService.cs
│   ├── ILoanService.cs
│   └── LoanService.cs
│
├── Migrations
├── Program.cs
└── appsettings.json

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API Endpoints

Authentication

Method	Endpoint	Description	Auth required
POST	/api/auth/register	Register a new user	No
POST	/api/auth/login	Login and receive a JWT	No

All other endpoints require a valid JWT Bearer token.

Books

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

Members

Method	Endpoint	Description
GET	/api/members	Get all members
GET	/api/members/{id}	Get member by ID
POST	/api/members	Create a new member
PUT	/api/members/{id}	Update a member
DELETE	/api/members/{id}	Delete a member

Loans

Method	Endpoint	Description
GET	/api/loans	Get all loans
GET	/api/loans/member/{memberId}	Get loans by member
POST	/api/loans/borrow	Borrow a book
PUT	/api/loans/return/{loanId}	Return a book

Example Payloads

Register

{
  "email": "admin@library.com",
  "password": "SecurePass123!",
  "role": "Admin"
}

Login

{
  "email": "admin@library.com",
  "password": "SecurePass123!"
}

Create Book

{
  "title": "Clean Code",
  "author": "Robert C. Martin",
  "isbn": "9780132350884",
  "publicationYear": 2008
}

Create Member

{
  "firstName": "Jane",
  "lastName": "Doe",
  "email": "jane.doe@example.com",
  "phone": "555-1234"
}

Borrow a Book

{
  "bookId": 1,
  "memberId": 1
}

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Running the Project

1. Clone the repository

git clone https://github.com/kayanr/library-management-system-dotnet-api.git

2. Navigate to the project

cd library-management-system-dotnet-api/LibraryManagement.Api

3. Restore dependencies

dotnet restore

4. Apply database migrations

dotnet ef database update

5. Run the API

dotnet run

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Swagger API Documentation

After running the project, open Swagger in your browser:

http://localhost:xxxx/swagger

Swagger allows you to interactively test all API endpoints.

To test protected endpoints in Swagger:

1. Call POST /api/auth/register to create a user
2. Call POST /api/auth/login to get a token
3. Click the Authorize button and enter your token
4. All subsequent requests will include the Bearer token

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Future Improvements

• React + TypeScript frontend
• Angular frontend
• Role-based authorization (Admin vs Member)
• PostgreSQL or SQL Server support
• Deployment (Railway / Render / Azure)

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