删除方法在Spring Boot&Thymeleaf中不起作用

Question

@Autowired
UserRepository userRepository;

@RequestMapping(value = "/students", method = RequestMethod.GET)
public String tables(Model model){
    model.addAttribute("users", userRepository.findAll());
    return "students";
}


@RequestMapping(value = "/delete/{id}", method = GET)
public String delete(Model model, @PathVariable("id") Long id){
    User user = userRepository.findById(id)
        .orElseThrow(() -> new IllegalArgumentException("Niepoprawne id : " + id));
    userRepository.deleteUserById(id);
    model.addAttribute("students", userRepository.findAll());
    return "redirect:/students";
}}

@Repository
public interface UserRepository extends JpaRepository<User,Long> {
    User findByEmail(String email);
    List<User> findAll();
   void deleteUserById(Long id);

}

@Service
public interface UserService extends UserDetailsService {

    User findByEmail(String email);
    User save(UserRegistrationDto registration);
    List<User> findAll();
    void deleteUserById(Long id);

}

和UserServiceImpl：

@Service
public class UserServiceImpl implements UserService {

    @Autowired
    private UserRepository userRepository;

    @Autowired
    private RoleRepository roleRepository;

    @Autowired
    private BCryptPasswordEncoder passwordEncoder;


    public User findByEmail(String email){
        return userRepository.findByEmail(email);
    }


    private Collection<? extends GrantedAuthority> mapRolesToAuthorities(Collection<Role> roles){
        return roles.stream()
            .map(role -> new SimpleGrantedAuthority(role.getName()))
            .collect(Collectors.toList());
    }

    public List<User> findAll(){
       return userRepository.findAll();
    }


    public void deleteUserById(Long id) {
        userRepository.deleteUserById(id);
    }
}

在前端，我创建了一个简单的表，如下所示：

<table class="table table-bordered" id="dataTable" width="100%" cellspacing="0" >
                            <thead>
                            <tr>
                                <th>IMIE</th>
                                <th>NAZWISKO</th>
                                <th>EMAIL</th>
                                <th>AKCJA</th>
                            </tr>
                            </thead>
                            <tbody>
                            <tr>
                            <tr th:each="user :${users}">
                                <td th:text="${user.firstName}"></td>
                                <td th:text="${user.lastName}"></td>
                                <td th:text="${user.email}"></td>
                                <td>
                                    <!--<a th:href="${'/students/delete/' + user.id}" class="btn btn-danger">Usuń</a>-->
                                <td><a th:href="@{/delete/{id}(id=${user.id})}">Delete</a></td>
                                </td>
                            </tr>
                            </tr>
                            </tbody>
                        </table>

现在，当我启动我的应用程序并单击删除按钮时，我在网站上出现了这样的错误：当前线程没有实际事务可用的EntityManager-不能可靠地处理“Remove”调用；嵌套异常是javax.persistence.TransactionRequiredException：当前线程没有实际事务可用的EntityManager-不能可靠地处理“Remove”调用

Answer 1

默认情况下，只有CRUD方法（CrudRepository方法）标记为事务性的。如果使用的是自定义查询方法，则应该用@transactional注释显式标记它。

因此，将@Transactional放在存储库类中的deleteUserById方法上，如下所示。

@Transactional
void deleteUserById(Long id);

参考这个