如何通过Thymeleaf表单创建（发布）与当前用户有关系的新实体？

Question

我是Spring的新手。我试图通过Thymeleaf形式创建一个新主题。用户和主题有一对多的关系。我想将创建的主题添加到当前用户。

当我尝试打开表单时，我收到以下错误：

BindingResult和bean名称＆＃39; subject＆＃39;都没有普通的目标对象。可用作请求属性

执行处理器＆＃39; org.thymeleaf.spring4.processor.SpringInputGeneralFieldTagProcessor＆＃39;时出错。 （模板：＆＃34; addSubject＆＃34; - 第22行，第45栏）

 User Enity:(not the whole class)

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long userId;

@OneToMany(fetch=FetchType.LAZY, cascade=CascadeType.ALL)
public List<Subject> subject;

public User() {
}

    public User(Long userId, List<Subject> subject, Collection<Role> roles, 
 String username, String password,
            String firstName, String surname, int age, double height, double 
  weight, String emailAddress, String gender,
        String dob, Boolean studentStatus) {
    super();
    this.userId = userId;
    this.subject = subject;
    this.roles = roles;
    this.username = username;
    this.password = password;
    this.firstName = firstName;
    this.surname = surname;
    this.age = age;
    this.height = height;
    this.weight = weight;
    this.emailAddress = emailAddress;
    this.gender = gender;
    this.dob = dob;
    this.studentStatus = studentStatus;
}

private String username;

private String password;

private String firstName;

private String surname;

private int age;

//@NotBlank
private String emailAddress;

//@NotBlank
private String gender;

//@NotBlank
private String dob;

public Long getUserId() {
    return userId;
}

public void setUserId(Long userId) {
    this.userId = userId;
}

public List<Subject> getSubject() {
    return subject;
}

  //Getters and setters are here

@Override
public Collection<? extends GrantedAuthority> getAuthorities() {
    // TODO Auto-generated method stub
    return null;
}

public void addSubject(Subject subjects) {
    subject.add(subjects);

}

添加主题控制器

@Controller
@RequestMapping("/addsubject")
  public class AddSubjectController {

@Autowired
private SubjectRepository subjectRepository;

@ModelAttribute("subject")
public Subject subject() {
    return new Subject();
}

@Autowired
UserRepository userR;
@GetMapping
public Long currentUser(@ModelAttribute("userx") @Valid UserRegistrationDto userDto, BindingResult result, Model model) {

    Authentication loggedInUser = SecurityContextHolder.getContext().getAuthentication();
    String email = loggedInUser.getName();   

    User user = userR.findByEmailAddress(email);
    String firstname = user.getFirstName();
    String surname = user.getSurname();
    Long userId = user.getUserId();

    return userId;
}


public String addSubject(Model model) {
    model.addAttribute("subject", new Subject());
    return "addSubject";
}

public String AddNewSubject(@Valid Subject subject, BindingResult bindingResult, Model model) {
    Authentication loggedInUser = SecurityContextHolder.getContext().getAuthentication();
    String email = loggedInUser.getName();   

    User user = userR.findByEmailAddress(email);

    subjectRepository.save(subject);
    model.addAttribute("subjectName", subject.getSubjectName());
    model.addAttribute("subjectGradeGoal", subject.getSubjectGradeGoal());
    model.addAttribute("subject", subject);
    user.addSubject(subject);
    return "userProfile1";
}

添加主题模板

添加主题

<h1>Add A Subject</h1>

<form action="#" th:action="@{/addsubject}" th:object="${subject}" method="post">
    <table>
        <tr>
        <td> Subject Name:</td>
            <td><input id="subjectName" type="text" th:field="*{subjectName}" /></td>
            <td th:if="${#fields.hasErrors('subjectName')}" th:errors="*{subjectName}">Surname error message</td> 
        </tr>  
        <tr>
            <td> What is your grade goal for this subject? (e.g 50%,60%,70%) </td>
            <td><inpurt type="double" th:fields="*{subjectGradeGoal}" /></td>
            <td th:if="${#fields.hasErrors('subjectGradeGoal')}" th:errors="*{subjectGradeGoal}">subjectGradeGoal error message</td>
            </tr>   
            <tr>
                <td><button type="submt">Submit post</button></td>
                </tr>
    </table>
</form>

 

我不认为主题对象可以在模型中找到。