Build E-Commerce Apps with Reactive Programming in Spring Boot/

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Showing the Cart

Showing the Cart

Learn how to load data through the reactive repository, its drawbacks, and a solution to use a nonreactive CRUD repository.

We'll cover the following...

Showing the cart on the web page

Before we start manipulating the cart, it would be useful to show it on the web page.

For this, we need to retool ourHomeController. To do that, we first need to inject our new repositories:

@Controller //1
public class HomeController {
    private ItemRepository itemRepository;
    private CartRepository cartRepository;
    
    public HomeController(ItemRepository itemRepository, CartRepository cartRepository) { //2
        this.itemRepository = itemRepository;
        this.cartRepository = cartRepository; 
    }
    ...
}
HomeController getting repositories via constructor injection

Here’s the breakdown of the code written above:

  1. In line 1, @Controller signals this as a Spring Web controller that serves up templated views.

  2. In line 6, the constructor is used by Spring to inject the itemRepository and the cartRepository. This is known as constructor injection, and it is a highly recommended tactic by the Spring team.

We can post a more sophisticated listing of our inventory and the cart with this in place.

public HomeController(ItemRepository itemRepository,
    CartRepository cartRepository) {
            ...
}
@GetMapping 
Mono<Rendering> home() { //1
    return Mono.just(Rendering.view("home.html") //2 
        .modelAttribute("items", 
            this.itemRepository.findAll()) //3 
        .modelAttribute("cart", 
            this.cartRepository.findById("My Cart") //4 
                .defaultIfEmpty(new Cart("My Cart")))
        .build()); 
}
Overhauled rendering for a Cart at the root URL
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