🧪 Task 1: Extend & Inhance the Books API

You already have a working Books API.

Your task is to extend it by adding a few new endpoints and improving existing ones.

Note that there is no need for having a Database or adding any external packages. All you need to do is create some new .cs files.

Requirements

1. Fix the “Get Single Book” endpoint

Current behavior: GET /books/{id} always returns the first book.

Your task is to update this endpoint so that:

• It returns the book with the matching id

• If the book does not exist, return 404 Not Found

📌 Hint: Use FirstOrDefault from LINQ.

2. Add an Update (PUT) endpoint

Create a new endpoint: PUT /books/{id}

Behavior:

• Accepts a BookRequest from the body

• Updates the Title and Category of the existing book

• If the book does not exist → return 404 Not Found

• If the category is invalid → return 400 Bad Request

• If successful → return 204 No Content

📌 Rules:

• The Id must not be changed

• Reuse the same allowed categories logic

3. Add a Get-By-Category endpoint

Create a new endpoint: GET /books/category/{category}

Behavior: Behavior:

• Returns all books that belong to the given category

• If no books exist in that category → return an empty list

• Category matching should be case-insensitive. (i.e sending GET /books/category/novel should behave the same as if we send GET /books/category/NOvel )

4. Prevent Duplicate Titles (Creating a Book)

Improve the existing POST endpoint: POST /books

New Rule:

• If a book with the same title already exists → return 400 Bad Request.
• Titles should be compared case-insensitively

Task 2: Add Authors to the API

You are going to extend the API by introducing Authors. This task focuses on:

• Creating a new model class.
• Creating a new controller.
• Practicing basic CRUD operations.

You need to create a new Author class as below:

public class Author
{
    public int Id { get; set; }
    public string Name { get; set; }
}

Create a new controller called AuthorsController with following details:

• Route: /authors.
• Use [ApiController].
• Inherit from ControllerBase.
• Store authors in a static in-memory list.
• Have some initial data. Start with at least 2 authors in the list, example below:

public static List<Author> authors = new List<Author>(){
    new Author { Id = 1, Name = "George Orwell" }
    new Author { Id = 2, Name = "Yuval Noah Harari" }
};

Requirements

1. Implement GET /authors

• It should return all authors in the list.

2. Implement GET /authors/{id}

• Returns a single author by id.
• If not found → return 404 Not Found.

3. POST /authors

• Accepts an AuthorRequest object from the request body (you need to create this class and it should contain only a string Name property)
• Automatically generates a new Id.
• Basic validation: If Name is empty or shorter than 3 characters → return 400 Bad Request
• If successful → return 201 Created

4. Implement DELETE /authors/{id}

• Deletes the author with the given id.
• If the author does not exist → return 404 Not Found.
• If deleted → return 204 No Content.