无法延迟实例化HashMap

Question

我有下一个错误：

Request processing failed; nested exception is org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: my.shop.common.fliPusto.origins.User.spectatingBooks, could not initialize proxy - no Session

我尝试使用Hibernate.initialize()和myObject.getMyMap().size()初始化Map，但是它们都抛出异常。

我的HashMap课程：

@Entity
@Table(name = "users")
public class User implements UserDetails {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;

...

@ElementCollection(fetch = FetchType.LAZY)
@CollectionTable(name = "spectatingBooks", joinColumns = @JoinColumn(name = 
"user_id"))
@MapKeyJoinColumn(name = "book_id")
@Column(name = "lastChapter")
private Map<Book, Long> spectatingBooks = new HashMap<Book, Long>();
}

当我将获取类型从Lazy更改为Eager时，一切正常，但是我认为这是错误的方式。

我的班上课试图增加一些书：

@Transactional
@Service
public class UserDetailsServiceImpl implements UserDetailsService, 
UserDetailsServiceImplInterface {

...

@Transactional
public Boolean addBookmark(User user, Long bookId) {
    Optional<Book> book = bookRepository.findById(bookId);

    if (book.isPresent()) {
        Hibernate.initialize(user);
        int size = user.getSpectatingBooks().size();    <--Exception
        user.getSpectatingBooks().put(book.get(), 
        Integer.toUnsignedLong(0));
        userRepository.save(user);
        return true;
    }

    return false;
}
}

是否有任何方法可以延迟地实例化HashMap或仅适用于Fetch.Eager？

Answer 1

我通过通过userRepository而不是@AuthenticationPrinciple吸引用户来解决它，但是也许存在另一种方法吗？

@Transactional
public Boolean addBookmark(Long userId, Long bookId) {
    Optional<Book> book = bookRepository.findById(bookId);
    Optional<User> userOp = userRepository.findById(userId);

    if (book.isPresent() && userOp.isPresent()) {
        User user = userOp.get();
        int size = user.getSpectatingBooks().size();
        user.getSpectatingBooks().put(book.get(), Integer.toUnsignedLong(0));
        userRepository.save(user);
        return true;
    }

    return false;
}