CRUD REST API with Spring Boot

Prerequisites: You should have completed Exercise 02 (Modelling an API) where you created a Book API with nested Author and Publisher objects.

Starting Point

You should already have:

• Model classes: Book, Author, and Publisher
• BookController with:
  • GET /api/books - Returns list of books
  • GET /api/books/{id} - Returns single book or 404

Now you will extend this API with CREATE, UPDATE, and DELETE operations.

Exercise 1 - Bonus: Customize JSON output order

Goal: Learn how to customize the order of fields in the JSON response.

1. In the Book class, use a Jackson annotation to specify the order of fields in the JSON output so that id comes first, followed by title, isbn, publishedYear, edition, author, and then publisher.
   • Hint: Use the @JsonPropertyOrder({"id", "title", "isbn", "publishedYear", "edition", "author", "publisher"}) annotation on the Book class.
2. Test the /api/books and /api/books/{id} endpoints again to verify that the JSON output reflects the specified field order.
3. (Optional) Apply similar ordering to the Author and Publisher classes.
4. Test the endpoints again to verify the changes.

Exercise 2 - POST, PUT, DELETE Operations

Goal: Fully implement CRUD operations for the Book resource.

2.1 - POST endpoint

1. Create a new endpoint POST /api/books in the BookController that accepts a Book object in the request body and returns the same book with a 201 Created status code. The ID should be auto-generated (you can simulate this by incrementing a static variable).
   • Hint: Use the @RequestBody annotation to bind the incoming JSON to a Book object.
   • Hint: Use @PostMapping for POST endpoints.
   • Hint: Use AtomicLong or Long for generating unique IDs.
2. Test the endpoint using Postman by sending a POST request to http://localhost:8080/api/books with a JSON body representing a new book (without an ID). Verify that the response contains the created book with an assigned ID.
3. Add a Location header to the response that points to the URL of the newly created book (e.g., /api/books/{id}).
   • Hint: You can use ResponseEntity.created(URI.create("/api/books/" + book.getId())).body(book) to set the Location header.

2.2 - PUT endpoint

1. Create a new endpoint PUT /api/books/{id} in the BookController that accepts a Book object in the request body and updates the existing book with the specified ID.
2. If the book with the specified ID does not exist, return a 404 Not Found response.
3. Test the endpoint using Postman by sending a PUT request to http://localhost:8080/api/books/{id} with a JSON body representing the updated book data. Verify that the response contains the updated book.

2.3 - DELETE endpoint

1. Create a new endpoint DELETE /api/books/{id} in the BookController that deletes the book with the specified ID and returns a 204 No Content status code.
2. If the book with the specified ID does not exist, return a 204 No Content response.
3. Test the endpoint using Postman by sending a DELETE request to http://localhost:8080/api/books/{id}. Verify that the response status code is 204 No Content.

Exercise 3 - Testing Your Complete API

Now that you have a full CRUD API, test all operations in sequence:

1. GET /api/books - Verify you see your initial 3+ books
2. POST /api/books - Add a new book (e.g., "Clean Code" by Robert C. Martin)
3. GET /api/books - Verify the new book appears in the list
4. GET /api/books/{id} - Retrieve the specific book you just created
5. PUT /api/books/{id} - Update the book (e.g., change the edition)
6. GET /api/books/{id} - Verify the update was successful
7. DELETE /api/books/{id} - Delete the book
8. GET /api/books/{id} - Verify you get a 404 Not Found