How to implement guide with lazy loading and nullpointerexception in jpa with spring boot
I'm wondering if anyone has experience with I've searched everywhere and can't find a clear answer... I'm working on a personal project and I'm working with a `NullPointerException` when trying to access a lazily loaded collection in my JPA entity after fetching it using Spring Data JPA. I have a parent entity `Order` that has a one-to-many relationship with an `OrderItem` entity. When I fetch an `Order` and try to get its `OrderItems`, I get a `NullPointerException` if the `Order` is not managed. Here's how my entities are set up: ```java @Entity public class Order { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; @OneToMany(mappedBy = "order", fetch = FetchType.LAZY) private List<OrderItem> items; } @Entity public class OrderItem { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; @ManyToOne @JoinColumn(name = "order_id") private Order order; } ``` In my service, I'm fetching the `Order` like this: ```java public Order getOrderById(Long id) { return orderRepository.findById(id).orElse(null); } ``` Then, in my controller, I'm trying to access the items: ```java @GetMapping("/orders/{id}") public ResponseEntity<Order> getOrder(@PathVariable Long id) { Order order = orderService.getOrderById(id); // This line throws NullPointerException List<OrderItem> items = order.getItems(); return ResponseEntity.ok(order); } ``` I've verified that the `Order` is fetched successfully but when I try to access `getItems()`, it throws `NullPointerException`. I suspect it might be related to the fact that the collection is lazily loaded. I even tried annotating the `items` list with `@Transactional` at the service level, but the question continues. Could anyone guide to understand why this is happening and how I can properly handle this situation without running into a `NullPointerException`? Iām using Spring Boot 2.5.4 and Hibernate 5.5.7.Final. For context: I'm using Java on Ubuntu. Any ideas what could be causing this? This is part of a larger service I'm building. Am I missing something obvious? This is for a CLI tool running on Windows 11. What would be the recommended way to handle this? I appreciate any insights!