使用Spring的Thymeleaf表单中的空字段，其他字段很好

Question

我对Spring Boot比较陌生。目前，我正在使用用户注册系统制作Spring应用程序，但我遇到了一个问题。表单中的一些字段在后端注册为‘null’，尽管请求已正确发布。

我有一个HTML/ Thymeleaf表单，它提交8个字段来创建一个“User”对象。以下是表格：

<form th:action="@{/users/register_attempt}" th:object="${user}"
      method="post" style="max-width: 600px; margin: 0 auto;">
    <div class="m-3">
        <div class="form-group row">
            <label class="col-4 col-form-label">DOB: </label>
            <div class="col-8">
                <input type="text" th:field="*{dob}" class="form-control" th:required="required" />
            </div>
        </div>
        <div class="form-group row">
            <label class="col-4 col-form-label">First Name: </label>
            <div class="col-8">
                <input type="text" th:field="*{name}" class="form-control" th:required="required" />
            </div>
        </div>

        <div class="form-group row">
            <label class="col-4 col-form-label">Surname: </label>
            <div class="col-8">
                <input type="text" th:field="*{surname}" class="form-control" th:required="required" />
            </div>
        </div>

        <div class="form-group row">
            <label class="col-4 col-form-label">PPSN: </label>
            <div class="col-8">
                <input type="text" th:field="*{ppsn}" class="form-control" th:required="required" />
            </div>
        </div>
        <div class="form-group row">
            <label class="col-4 col-form-label">Address: </label>
            <div class="col-8">
                <input type="text" th:field="*{address}" class="form-control" th:required="required" />
            </div>
        </div>
        <div class="form-group row">
            <label class="col-4 col-form-label">Phone Number: </label>
            <div class="col-8">
                <input type="number" th:field="*{phone}" class="form-control"  />
            </div>
        </div>

        <div class="form-group row">
            <label class="col-4 col-form-label">E-mail: </label>
            <div class="col-8">
                <input type="email" th:field="*{email}" class="form-control" th:required="required" />
            </div>
        </div>
        <div class="form-group row">
            <label class="col-4 col-form-label">Password: </label>
            <div class="col-8">
                <input type="password" th:field="*{password}" class="form-control"
                       required minlength="6" maxlength="10" th:required="required"/>
            </div>
        </div>

        <div>
            <button type="submit" class="btn btn-primary">Sign Up</button>
        </div>
    </div>
</form>

下面是表单代码要模仿的模型：

public class User {
@Id
@GeneratedValue
private Long id;

@NotBlank
private String dob;
@NotBlank
private String name;
@NotBlank
private String surname;
@NotBlank
private String ppsn;
@NotBlank
private String address;
@NotBlank
private String phone;
@NotBlank
@Column(unique = true)
private String email;

private String nextApptId;

private String dose1Date;

private String dose2Date;

private String lastLogin;
@NotBlank
private String password;

public User() {
    super();
}

public User(String dob, String name, String surname, String ppsn, String address, String phone, String email, String password) {
    super();
    this.dob = dob;
    this.name = name;
    this.surname = surname;
    this.ppsn = ppsn;
    this.address = address;
    this.phone = phone;
    this.email = email;
    this.password = password;
}
 public Long getId() {
    return id;
}

public String getDob() {
    return dob;
}

public String getName() {
    return name;
}

public String getSurname() {
    return surname;
}

public String getPpsn() {
    return ppsn;
}

public String getAddress() {
    return address;
}

public void setAddress(String address) {
    this.address = address;
}

public String getPhone() {
    return phone;
}

public void setPhone(String phone) {
    this.phone = phone;
}

public String getEmail() {
    return email;
}

public void setEmail(String email) {
    this.email = email;
}

public String getNextApptId() {
    return nextApptId;
}

public void setNextApptId(String apptId) {
    this.nextApptId = apptId;
}

public String getDose1Date() {
    return dose1Date;
}

public void setDose1Date(String dose1Date) {
    this.dose1Date = dose1Date;
}

public String getDose2Date() {
    return dose2Date;
}

public void setDose2Date(String dose2Date) {
    this.dose2Date = dose2Date;
}

public String getLastLogin() {
    return lastLogin;
}

public void setLastLogin(String lastLogin) {
    this.lastLogin = lastLogin;
}

public String getPassword() {
    return password;
}

public void setPassword(String password) {
    this.password = password;
}
}

但由于某些原因，我无法确定前四个字段--即道布(出生日期)、姓名、姓氏和PPSN --在服务器端实例化用户对象时产生了一个空错误，例如：

     `Resolved [org.springframework.validation.BindException: org.springframework.validation.BeanPropertyBindingResult: 4 errors<EOL>
Field error in object 'user' on field 'dob': rejected value [null]; codes [NotBlank.user.dob,NotBlank.dob,NotBlank.java.lang.String,NotBlank]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [user.dob,dob]; arguments []; default message [dob]]; default message [must not be blank] `.

其他四个字段，地址、电话、电子邮件和密码似乎运行得很好。

据我所知，这不是一个错误问题(如果结果是这样的话，请原谅我)。我使用Burp截获了Post请求，以检查字段的内容是否从表单中输入到请求中，并为我的User类中的字段提供了正确的名称，实际上它们都在其中。

我认为这意味着问题来自后端控制器代码是如何基于模型解释这个post请求的，但我并不真正知道如何或从何处开始。以下是当前控制器：

@GetMapping("/register")
    public String startRegistration(Model model) {
        model.addAttribute("user", new User());
        return "register";
    }  

@PostMapping("/register_attempt")
    public String registerAttempt(@Valid User newUser) {
        BCryptPasswordEncoder passwordEncoder = new BCryptPasswordEncoder();
        String encodedPassword = passwordEncoder.encode(newUser.getPassword());
        newUser.setPassword(encodedPassword);
        userRepository.save(newUser);
        return "registered_successfully";
    }

编辑:对持久化问题的进一步调试和澄清

从Post中删除@Valid注释并使用老式的print语句显示相同的结果--前四个字段为null，原因不明显。

    @PostMapping("/register_attempt")
public String registerAttempt(@ModelAttribute("user") User newUser) {
    System.out.println("Saving user ");
    System.out.println("Name " + newUser.getName());
    System.out.println("Last Name " + newUser.getSurname());
    System.out.println("PPSN " +newUser.getPpsn());
    System.out.println("DOB " +newUser.getDob());
    System.out.println("email " +newUser.getEmail());
    System.out.println("address " +newUser.getAddress());
    System.out.println("encrypted password " +newUser.getPassword());
    System.out.println("Phone num " +newUser.getPhone());
    userRepository.save(newUser);
    System.out.println("User saved");
    return "registered_successfully";
}

使用以下虚拟数据：

​

​

它将此Post请求发送到后端：

​

​

这些打印报表的结果：

Saving user 
name null
last Name null
ppsn null
dob null
email foo@bar.com
address Here and there
password password
Phone num 987654321

这些错误信息是：

javax.validation.ConstraintViolationException: Validation failed for classes [app.model.User] during persist time for groups [javax.validation.groups.Default, ]
List of constraint violations:[
    ConstraintViolationImpl{interpolatedMessage='must not be blank', propertyPath=surname, rootBeanClass=class app.model.User, messageTemplate='{javax.validation.constraints.NotBlank.message}'}
    ConstraintViolationImpl{interpolatedMessage='must not be blank', propertyPath=dob, rootBeanClass=class app.model.User, messageTemplate='{javax.validation.constraints.NotBlank.message}'}
    ConstraintViolationImpl{interpolatedMessage='must not be blank', propertyPath=name, rootBeanClass=class app.model.User, messageTemplate='{javax.validation.constraints.NotBlank.message}'}
    ConstraintViolationImpl{interpolatedMessage='must not be blank', propertyPath=ppsn, rootBeanClass=class app.model.User, messageTemplate='{javax.validation.constraints.NotBlank.message}'}
]

如果你有任何洞察力，这可能会发生，我将非常感谢。

Answer 1

Thymeleaf模板中有th:object="${user}"，所以我必须假设控制器中的@GetMapping方法使用addAttribute将User实例添加到Model中。

在您的@PostMapping中，还应该使用@ModelAttribute

@PostMapping("/register_attempt")
public String registerAttempt(@Valid @ModelAttribute("user") User newUser) {
  ...

您还需要为每个字段设置setter。我看到User没有setName(String name)，没有setDob(String dob)，.

其他一些小窍门：

1. 不要在控制器方法本身中创建BCryptPasswordEncoder实例。当您使用Spring时，这应该是一个应用程序范围的单例(在Spring中称为bean )。在应用程序中添加一个类，例如ReservationSystemApplicationConfiguration，它声明如下：

@Configuration
public class ReservationSystemApplicationConfiguration {
  @Bean
  public PasswordEncoder passwordEncoder() {
     return new BCryptPasswordEncoder();
  }
}

然后，在控制器中插入密码编码器：

@Controller
@RequestMapping("...")
public class MyController {

  private final PasswordEncoder passwordEncoder;

  public MyController(PasswordEncoder passwordEncoder) {
    this.passwordEncoder = passwordEncoder;
  }

  @PostMapping("/register_attempt")
  public String registerAttempt(@Valid @ModelAttribute("user") User newUser) {
    String encodedPassword = passwordEncoder.encode(newUser.getPassword());
    newUser.setPassword(encodedPassword);
    userRepository.save(newUser);
    return "registered_successfully";
  }
}

1. 控制器不应直接调用存储库，而应在两者之间使用服务。
2. 最好使用不同的对象来映射表单数据并将数据存储到数据库中。有关如何做到这一点的更多信息，请参见用Thymeleaf处理表单。