休眠“参数值与预期类型不匹配”

Question

我想使用 Spring 框架和 Hibernate 将 List<Completed> 对象插入到关系表中。

我的实体类有 Collections List 字段 -

@Entity
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;

    ...
    
    @OneToMany(mappedBy = "user", cascade = CascadeType.ALL)
    private List<Completed> completedList;

    ... // getters/setters
}

数据访问存储库 -

public interface UserRepository extends CrudRepository<User, Long> {

    Optional<User> findByEmail(String email);

    @Modifying
    @Query(value = "update User set completedList = :completed where id = :id")
    @Transactional
    void addNewCompletion(@Param("completed") List<Completed> completed,
                          @Param("id") long userID);
}

我正在调用该方法（出于测试目的）-

        Completed completed1 = new Completed(1, LocalDateTime.now());
        Completed completed2 = new Completed(2, LocalDateTime.now());
        Completed completed3 = new Completed(3, LocalDateTime.now());
        List<Completed> completedList = List.of(completed1, completed2, completed3);
//        completedList.add(completed1);
        UserService.updateUserCompletion(completedList, UserService.findUserID(currentUser));

我也试过了-

    List<Completed> completedList = new ArrayList()<>;
    completedList.add(new Completed()); // etc.

   Completed completed = new Completed(1, LocalDateTime.now());
   UserService.updateUserCompletion(completed, UserService.findUserID(currentUser));

无论哪种方式都会导致相同的异常 -

java.lang.IllegalArgumentException: Parameter value [io.github.siaust.web_quiz_app.Model.Completed@2f1eafc2] did not match expected type [java.util.Collection (n/a)]

我无法理解，因为我将List<Completed> 对象传递给自定义@Query 的@Param？为什么类型不匹配？

Answer 1

不可能像这样更新数据库关系。 Collections 是一种特定类型，并以这种方式提供对象列表，您无需更改 Hibernate 即可将其识别为列表并正确处理它。当您使用@Query 时，hibernate 只需运行您的 SQL 代码。这意味着 Hibernate 将一个集合作为参数传递到您的 SQL 代码中，并且数据库服务器无法解析该集合您还创建了一个不可变的集合，该集合在这里也不起作用。我认为在你的情况下这应该可以正常工作：

User user = UserService.findUserID(currentUser);

List<Completed> completedList = new ArrayList<>();
completedList.add(new Completed(1, LocalDateTime.now()));
completedList.add(new Completed(2, LocalDateTime.now()));
completedList.add(new Completed(3, LocalDateTime.now()));


user.setCompleted(completedList);
userRepository.save(user);