🌱 @Valid와 @Validated

@RestController
@RequestMapping("/api/products")
public class ProductController {

    private final ProductService productService;

    public ProductController(final ProductService productService) {
        this.productService = productService;
    }

    @PostMapping
    public ResponseEntity<Void> add(@Validae @RequestBody final ProductDto productDto) {
        final Long productId = productService.addProduct(productDto);
        final URI uri = ServletUriComponentsBuilder
                .fromCurrentRequest()
                .path("/" + productId)
                .build().toUri();
        return ResponseEntity.created(uri).build();
    }
 		
  	// ...
}

public class ProductDto {
    @NotNull
    private Long productId;

    @NotBlank
    private String name;

    @Min(value = 0, message = "금액은 음수일 수 없습니다.")
    private Integer price;

    @NotBlank
    private String imageUrl;

    public ProductDto() {
    }
     
 		// ...
}

public interface Request {
    interface id {
    }

    interface allProperties {
    }
}

public class ProductDto {
    @NotNull(groups = Request.id.class)
    private Long productId;

    @NotBlank(groups = Request.allProperties.class)
    private String name;

    @Min(value = 0, message = "금액은 음수일 수 없습니다.", groups = Request.allProperties.class)
    private Integer price;

    @NotBlank(groups = Request.allProperties.class)
    private String imageUrl;

    public ProductDto() {
    }

    // ...
}

@RestController
@RequestMapping("/api/products")
public class ProductController {

    private final ProductService productService;

    public ProductController(final ProductService productService) {
        this.productService = productService;
    }
		
  	// ...
  
    @PostMapping
    public ResponseEntity<Void> add(@Validated(Request.allProperties.class) @RequestBody final ProductDto productDto) {
        final Long productId = productService.addProduct(productDto);
        final URI uri = ServletUriComponentsBuilder
                .fromCurrentRequest()
                .path("/" + productId)
                .build().toUri();
        return ResponseEntity.created(uri).build();
    }
		// ...
}

@RestController
@RequestMapping("/api/customers/{customerName}/carts")
public class CartItemController {
    private final CartService cartService;

    public CartItemController(final CartService cartService) {
        this.cartService = cartService;
    }
		// ...

    @PostMapping
    public ResponseEntity<Void> addCartItem(@Validated(Request.id.class) @RequestBody final ProductDto productDto,
                                            @PathVariable final String customerName) {
        final Long newId = cartService.addCart(productDto.getProductId(), customerName);
        final URI uri = ServletUriComponentsBuilder
                .fromCurrentRequest()
                .path("/{cartId}")
                .buildAndExpand(newId)
                .toUri();
        return ResponseEntity.created(uri).build();
    }
		// ...
}

public class OrderDetailDto {

    @NotNull(groups = Request.allProperties.class)
    private Long productId;
    private Long cartId;
    private int price;
    private String name;
    private String imageUrl;

    @Min(value = 0, groups = Request.allProperties.class)
    private int quantity;

    public OrderDetailDto() {
    }

    // ...
}

@RestController
@RequestMapping("/api/customers/{customerName}/orders")
public class OrderController {
    private final OrderService orderService;

    public OrderController(final OrderService orderService) {
        this.orderService = orderService;
    }

    @PostMapping
    public ResponseEntity<Void> addOrder(@PathVariable final String customerName,
                                         @RequestBody @Valid final List<OrderDetailDto> orderDetailRequestDtos) {
        long orderId = orderService.addOrder(orderDetailRequestDtos, customerName);
        return ResponseEntity.created(
                URI.create("/api/" + customerName + "/orders/" + orderId)).build();
    }

   // ...
}