我是 Spring 新手，我可能犯了最愚蠢的錯誤，但我無法解決這個問題超過 2 小時。根據視頻教程，我做了分頁，我做的和他的一模一樣，但他沒有物體之間的關系。我認為錯誤在于作者和書籍物體之間的一對一關系。你能幫忙嗎？
我想添加分頁，因為我的表中有超過一百萬條記錄，添加分頁后出現此錯誤。
圖書物體：
@Entity
@Table(name = "books")
public class Book {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
private Long id;
@Column(name = "title")
private String title;
@Column(name = "publishing_year")
private Integer publishingYear;
@Column(name = "sell_cost")
private BigDecimal sellCost;
@Column(name = "rent_cost")
private BigDecimal rentCost;
@Column(name = "amount")
private Integer amount;
@OneToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "author_id")
private Author author;
//getter and setters
作者物體：
@Entity
@Table(name = "author")
public class Author {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
private Long id;
@Column(name = "fullname")
private String fullname;
@Column(name = "birthday")
private Date birthday;
@OneToOne(mappedBy = "author")
private Book book;
//getters and setters
BookServiceImpl 類：
@Service
public class BookServiceImpl implements BookService
{
@Autowired
private BookRepository bookRepository;
@Override
public Page<Book> findPaginated(int pageN, int pageSize,String sortField,String sortDirection) {
Sort sort = sortDirection.equalsIgnoreCase(Sort.Direction.ASC.name()) ? Sort.by(sortField).ascending() :
Sort.by(sortField).descending();
Pageable pageable = PageRequest.of(pageN-1,pageSize,sort);
return bookRepository.findAll(pageable);
}
}
圖書館員控制器類：
@GetMapping("/books/{pageN}")
public String getAllBooks(@PathVariable (value = "pageN") int pageN,Model model,
@RequestParam("sortField") String sortField,
@RequestParam("sortDir") String sortDir){
int pageSize = 25;
Page<Book> page = bookService.findPaginated(pageN,pageSize,sortField,sortDir);
List<Book> books = page.getContent();
model.addAttribute("currentPage",pageN);
model.addAttribute("totalPages",page.getTotalPages());
model.addAttribute("totalItems", page.getTotalElements());
model.addAttribute("books",books);
model.addAttribute("sortField",sortField);
model.addAttribute("sortDir",sortDir);
model.addAttribute("reverseSortDir",sortDir.equals("asc") ? "desc" : "asc");
return "librarian/show-all-books";
}
uj5u.com熱心網友回復：
您似乎有一個 Book 記錄，該記錄參考了 ID 為 10000001 的 Author 并沒有出現在 Author 表中。
uj5u.com熱心網友回復：
試試這些改變。我希望每本書只有一個作者。
書.java：
@ManyToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "author_id")
private Author author;
作者.java：
@OneToMany(mappedBy = "author")
private List<Book> books=new ArrayList<>();
轉載請註明出處，本文鏈接：https://www.uj5u.com/caozuo/474893.html
上一篇：說說最近linux運維那些事