javax。坚持不懈EntityNotFoundException:找不到kg。图书馆SpringSpring图书馆。实体id为10000001的作者

Question

我刚接触Spring，我可能犯了最愚蠢的错误，但我不能解决这个问题超过2个小时。根据视频教程，我做了分页，我做的和他的一模一样，但他在实体之间没有关系。我认为错误在于作者和图书实体之间的一对一关系。你能帮忙吗？

我想添加分页，因为我的表中有100多万条记录，在添加分页后，我出现了这个错误。

账簿实体：

@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

作者实体：

    @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类：

@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);
}

}

LibrarianController类：

@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";
}

Answer 1

试试这些改变。我希望每本书只有一位作者。

Book.java：

    @ManyToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "author_id")
    private Author author;

著者爪哇：

    @OneToMany(mappedBy = "author")
    private List<Book> books=new ArrayList<>();

Answer 2

似乎有一个图书记录引用了一个id为10000001的作者，但该作者不在Author表中。