hateoas

# Spring HATEOAS ## Dependency ```xml <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-hateoas</artifactId> </dependency> ``` ## When to Add Links - `self` — always, on every resource response - `collection` — link back to the list endpoint - `related resources` — when a client commonly needs to navigate to them - `actions` — links to state transitions (e.g., `cancel`, `ship`) when valid for current state ## Resource Model ```java public class OrderModel extends RepresentationModel<OrderModel> { private final UUID id; private final String status; private final String customerEmail; private final Instant createdAt; // Static factory with links public static OrderModel from(Order order) { OrderModel model = new OrderModel( order.getId(), order.getStatus().name(), order.getCustomerEmail(), order.getCreatedAt() ); // Self link — always model.add(linkTo(methodOn(OrderController.class).getById(order.getId())).withSelfRel()); // Collection link model.add(linkTo(methodOn(OrderController.class).list(null)).withRel("orders")); // Conditional action links based on state if (order.getStatus() == OrderStatus.PENDING) { model.add(linkTo(methodOn(OrderController.class) .cancelOrder(order.getId())).withRel("cancel")); } if (order.getStatus() == OrderStatus.PROCESSING) { ...