Library Management System API

A RESTful Web API for managing library books with JWT-based authentication built with ASP.NET Core.

Features

• User registration and login
• JWT-based authentication
• CRUD operations for books (Create, Read, Update, Delete)
• Search books by title or author
• Entity Framework Core with MSSQL
• Database seeding with sample data
• Clean architecture with layered design
• Comprehensive error handling
• Swagger UI for API documentation

Technology Stack

• Framework: ASP.NET Core 8.0
• Database: Microsoft SQL Server
• ORM: Entity Framework Core
• Authentication: JWT Bearer Token
• Documentation: Swagger/OpenAPI

Prerequisites

• .NET 8.0 SDK
• SQL Server or SQL Server LocalDB
• Visual Studio 2022 or Visual Studio Code

Setup Instructions

1. Clone the Repository

git clone https://github.com/Juninhotech/LibraryManagementAPI.git
cd LibraryManagementAPI

2. Configure Database Connection

Update the connection string in appsettings.json:

"ConnectionStrings": {
  "DefaultConnection": "Server=(localdb)\\mssqllocaldb;Database=LibraryManagementDb;Trusted_Connection=true;TrustServerCertificate=true;"
}

For SQL Server:

"DefaultConnection": "Server=localhost;Database=LibraryManagementDb;User Id=sa;Password=YourPassword;TrustServerCertificate=true;"

3. Install Dependencies

dotnet restore

4. Apply Database Migrations

dotnet ef migrations add InitialCreate
dotnet ef database update

Note: The database will be automatically seeded with sample books on the first run.

5. Run the Application

dotnet run

The API will start at:

• HTTP: http://localhost:5226

Testing the API

Using Swagger UI

1. Navigate to http://localhost:5226/swagger
2. Test endpoints directly from the browser

Using Postman or cURL

1. Register a New User

POST https://localhost:5226/api/auth/register
Content-Type: application/json

{
  "username": "testuser",
  "email": "test@example.com",
  "password": "Password123!"
}

Response:

{
  "username": "testuser",
  "email": "test@example.com"
}

2. Login

POST https://localhost:5226/api/auth/login
Content-Type: application/json

{
  "token": "eyJhbGciOiJIUzI1NiIs...",
  "username": "testuser",
  "password": "Password123!"
}

3. Get All Books (Requires Authentication)

GET https://localhost:5226/api/books
Authorization: Bearer <your-jwt-token>

4. Search Books

GET https://localhost:5226/api/books?search=clean
Authorization: Bearer <your-jwt-token>

5. Get Book by ID

GET https://localhost:5226/api/books/1
Authorization: Bearer <your-jwt-token>

6. Create a New Book

POST https://localhost:5226/api/books
Authorization: Bearer <your-jwt-token>
Content-Type: application/json

{
  "title": "Domain-Driven Design",
  "author": "Eric Evans",
  "isbn": "978-0321125217",
  "publishedDate": "2003-08-20T00:00:00"
}

7. Update a Book

PUT https://localhost:5226/api/books/1
Authorization: Bearer <your-jwt-token>
Content-Type: application/json

{
  "title": "Clean Code - Updated",
  "author": "Robert C. Martin",
  "isbn": "978-0132350884",
  "publishedDate": "2008-08-01T00:00:00"
}

8. Delete a Book

DELETE https://localhost:5226/api/books/1
Authorization: Bearer <your-jwt-token>

API Endpoints

Authentication

Method	Endpoint	Description	Auth Required
POST	/api/auth/register	Register new user	No
POST	/api/auth/login	Login user	No

Books

Method	Endpoint	Description	Auth Required
GET	/api/books	Get all books	Yes
GET	/api/books?search={term}	Search books	Yes
GET	/api/books/{id}	Get book by ID	Yes
POST	/api/books	Create new book	Yes
PUT	/api/books/{id}	Update book	Yes
DELETE	/api/books/{id}	Delete book	Yes

Authentication Flow

1. Register a new user or login with existing credentials
2. Receive a JWT token in the response
3. Include the token in the Authorization header for all protected endpoints:

   Authorization: Bearer <your-jwt-token>
   

Database Schema

Books Table

• Id (int, Primary Key)
• Title (nvarchar(200), Required)
• Author (nvarchar(100), Required)
• ISBN (nvarchar(20), Required, Unique)
• PublishedDate (datetime2)

Users Table

• Id (int, Primary Key)
• Username (nvarchar(50), Required, Unique)
• Email (nvarchar(100), Required, Unique)
• PasswordHash (nvarchar(max), Required)
• CreatedAt (datetime2)

Sample Data

The database is seeded with 5 programming books:

1. Clean Code - Robert C. Martin
2. The Pragmatic Programmer - Andrew Hunt and David Thomas
3. Design Patterns - Gang of Four
4. C# in Depth - Jon Skeet
5. Refactoring - Martin Fowler

Error Handling

The API returns appropriate HTTP status codes:

• 200 OK - Successful GET/PUT requests
• 201 Created - Successful POST requests
• 204 No Content - Successful DELETE requests
• 400 Bad Request - Invalid input data
• 401 Unauthorized - Missing or invalid token
• 404 Not Found - Resource not found
• 500 Internal Server Error - Server errors

Security Considerations

• Passwords are hashed using Bcrypt
• JWT tokens expire after 60 mins (configurable)
• All book endpoints require authentication
• SQL injection protection via EF Core parameterized queries

Troubleshooting

Database Connection Issues

• Verify SQL Server is running
• Check connection string in appsettings.json
• Ensure database exists or migrations have been applied

JWT Token Issues

• Ensure the token is included in the Authorization header
• Check token expiration (default 24 hours)
• Verify the JWT secret key matches in configuration

Additional Notes

• The project follows Repository and Service patterns for clean separation of concerns
• Dependency injection is used throughout the application
• The API uses DTOs to separate domain models from API contracts
• Comprehensive logging is implemented for debugging

Future Enhancements

• Add pagination for book listing
• Implement role-based authorization (Admin/User)
• Add book categories and tags
• Implement book borrowing system
• Add unit and integration tests
• Implement refresh tokens
• Add API rate limiting