Building REST APIs

@RestController
@RequestMapping("/api/v1/products")
public class ProductController {
  private final ProductService svc;
  public ProductController(ProductService svc) { this.svc = svc; }

  @GetMapping public List<ProductDto> list() { return svc.findAll(); }
  @GetMapping("/{id}") public ProductDto byId(@PathVariable long id) { return svc.find(id); }
  @PostMapping
  @ResponseStatus(HttpStatus.CREATED)
  public ProductDto create(@Valid @RequestBody NewProduct body) { return svc.create(body); }
}

@GetMapping("/users/{userId}/orders/{orderId}")
public OrderDto get(@PathVariable Long userId,
                    @PathVariable("orderId") UUID id) { /* … */ }

public record NewUser(@NotBlank String email, @Size(min=8) String password) {}

@PostMapping
public ResponseEntity<Void> create(@Valid @RequestBody NewUser body) {
  long id = service.register(body);
  return ResponseEntity.created(URI.create("/api/users/" + id)).build();
}

@PostMapping
@ResponseStatus(HttpStatus.CREATED)
public ProductDto create(@RequestBody NewProduct p) { /* … */ }

@ResponseStatus(value=HttpStatus.NOT_FOUND, reason="Order not found")
public class OrderNotFoundException extends RuntimeException {}

@GetMapping("/{id}")
public EntityModel<Order> one(@PathVariable Long id) {
  Order o = repo.findById(id).orElseThrow();
  return EntityModel.of(o,
    linkTo(methodOn(OrderController.class).one(id)).withSelfRel(),
    linkTo(methodOn(OrderController.class).all()).withRel("orders"));
}