在 SpringBoot 中从数据库中删除项目时出错：无法删除或更新父行：外键约束失败

Question

I have two tables, item and user, userId is a foreign key in item table using @ManyToOne mapping. I need to delete an item just by pressing a button on a bootstrap front end but I get the error: Cannot delete or update a parent row: a foreign key constraint fails ( jdbc . ms_item , CONSTRAINT FKli14y8viufmofrho0tdmgqawy FOREIGN KEY ( id ) REFERENCES ms_users ( id )). I understand that I can't delete a row from a db which has reference to another entity so Im wondering how I can delete. Another thing to note is that update works fine!

Here is my code:

@Controller
public class ProductController {

@Autowired
private ItemRepository itemRepository;
@Autowired
private UserRepository userRepository;

@Autowired
private ItemServiceImp itemServiceImp;

@GetMapping("/listItems")
public String listing(Model model) {
    model.addAttribute("item", new Item());
    model.addAttribute("pageTitle", "Sell Product");
    return "addItem";
}

@GetMapping("/products")
public String listItems(Model model, Principal principal) {
    User user = userRepository.findByEmail(principal.getName());
    List<Item> listItems = itemRepository.findByUser(user);
    model.addAttribute("listItems", listItems);
    return "productList";
}

@PostMapping("/products/save")
public String itemAdd(Item item, Principal principal, RedirectAttributes redirectAttributes) {
    User user = userRepository.findByEmail(principal.getName());
    item.setUser(user);
    itemRepository.save(item);
    redirectAttributes.addFlashAttribute("message", "Product Listed for sale");
    return "home_page";
}

@GetMapping("/products/update/{itemId}")
    public String updateItem(@PathVariable("itemId") Long itemId, Model model, RedirectAttributes redirectAttributes) {
    try {
        Item item = itemServiceImp.get(itemId);
        model.addAttribute("item", item);
        model.addAttribute("pageTitle", "Update Product");
        return "addItem";
    } catch (ItemNotFoundException e) {
        redirectAttributes.addFlashAttribute("message", "Product Updated");
        return "home_page";
    }

}

@GetMapping("/products/delete/{itemId}")
public String deleteItem(@PathVariable("itemId") Long itemId) {

    itemServiceImp.delete(itemId);
    return "redirect/productList";
}

}


@Entity
@Table(name = "msItem")
public class Item {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private long itemId;
@Column(nullable = false, length = 45)
private String itemName;
@Column(nullable = false)
private int itemPrice;
@Column(nullable = false, length = 100)
private String itemDesc;
@Column(nullable = false, length = 100)
private String category;
@Column(nullable = false, length = 100)
private String image;
@ManyToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    @JoinColumn(name = "id")
    private User user;


@Service
public class ItemServiceImp{

@Autowired
private ItemRepository itemRepository;

public List<Item> listItems(User user) {
     return itemRepository.findByUser(user);
}

public Item get(Long itemId) throws ItemNotFoundException {
    Optional<Item> result = itemRepository.findById(itemId);

    if (result.isPresent()) {
        return result.get();
    }

    throw new ItemNotFoundException("No Item with id: " + itemId);
}

public void delete(Long itemId) {
    itemRepository.deleteById(itemId);
}
}

Answer 1

best practice is to have remove boolean in your document and make it true or false it cause to have soft delete instead of hard delete