问带有Thymeleaf和SpringBoot的下拉列表
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Stack Overflow用户

提问于 2016-02-29 06:20:35

回答 1查看 15.8K关注 0票数 3

我有一个SpringBoot1.3应用程序，它在HTML上使用Thymeleaf。我有一页用户，当我编辑他们，我希望用户机构从一个列表中选择。我有一个窗口正确地显示了一切，但是当我选择机构时，控制器没有显示所选的值。

以下是我的HTML：

 <div class="form-group">
     <label class="col-md-3 control-label">Institution</label>
         <div class="col-md-5">
         <div th:if="${institutionList != null and not #lists.isEmpty(institutionList)}">
             <select>
                 <option th:each="dropDownItem : ${institutionList}"
                                 th:value="${dropDownItem.name}"
                                 th:text="${dropDownItem.name}" />
             </select>
        </div>
        <div th:if="${institutionList == null or lists.isEmpty(institutionList)}">
            <div>"No Institutions were found, please create some first"</div>
        </div>
    </div>
 </div>

这是我的控制器

@Controller
@PreAuthorize("hasRole('Admin')")
@RequestMapping("/admin")
public class AdminController {
    @Transactional
    @PreAuthorize("hasRole('ADMIN')")
    @RequestMapping(value = "/addUser", method = RequestMethod.POST)
    public String checkPersonInfo(@ModelAttribute User user, Model model, Authentication authentication) {
        // user does not have the selected institution set
        customUserDetailsService.createNewUser(user);
        updateModelWithAllUsers(model);
        return "admin";
    }

    private void updateModelWithAllUsers(Model model) {
        model.addAttribute(USERLIST, customUserDetailsService.findAllUsers());
        model.addAttribute(INSTITUTION_LIST, institutionService.findAll());
        model.addAttribute("user", new User());
    }

...
}

这是我的用户：

@Entity
@Table(name = "Users")
public class User implements UserDetails {
 @Id
    private String username;

    @Column(nullable = false)
    private String password;

    private boolean enabled;
    private boolean accountNonExpired;
    private boolean accountNonLocked;
    private boolean credentialsNonExpired;
    private String companyName;
    private String email;

    @ElementCollection(fetch=FetchType.EAGER)
    @CollectionTable(name="Authorities", joinColumns=@JoinColumn(name="username"))
    @Column(name="authority")
    private Set<String> roles = new HashSet<String>();

    @ManyToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    @JoinColumn(name = "institutionId", nullable = false)
    private Institution institution;
... getters & setters
}

我的机构：

@Entity
@Table(name = "Institution")
public class Institution {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long institutionId;
    private String name;

    @OneToMany(mappedBy = "institution", fetch = FetchType.EAGER)
    @Fetch(value = FetchMode.SUBSELECT)
    List<User> users = new ArrayList<User>();
    ... getters & setters
}

当"/addUser“从UI中获取用户对象时，机构为null。

我使用Sergios建议使用select th:field="${user.institution}"和select th:field="*{institution}"

但这给了我一个错误：

org.springframework.validation.BeanPropertyBindingResult: 1在字段‘com.security.Institution@3e3945d2’上的对象'user‘中的字段错误:拒绝值com.security.Institution@3e3945d2；代码typeMismatch.user.institution、typeMismatch.institution、typeMismatch.com。参数[org.springframework.context.support.DefaultMessageSourceResolvable:代码，制度；参数[]；默认消息机构；默认消息未能将属性' java.lang.String‘类型的属性值转换为属性’制度‘所需的类型'com.security.Institution’；嵌套异常是org.springframework.core.convert.ConversionFailedException:未能从java.lang.String类型转换为值‘com.security.Institution@3e3945d2’的java.lang.Long类型；嵌套异常是java.lang.NumberFormatException: For input string："com。.security.Institution@3e3945d2“

不确定我是否正确地阅读了这篇文章，但这是否意味着Thymeleaf试图将Institution.name传递给user.institution字段？

有人能就如何做到这一点提出建议吗？

spring-mvc

spring-boot

thymeleaf

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回答 1

Stack Overflow用户

回答已采纳

发布于 2016-02-29 06:42:13

您已经忘记指出必须从其中选取所选值的字段：

示例:我假设用户类有一个机构属性。

<div class="form-group">
 <label class="col-md-3 control-label">Institution</label>
     <div class="col-md-5">
     <div th:if="${institutionList != null and not #lists.isEmpty(institutionList)}">
         <select th:field="*{institution}">
             <option th:each="dropDownItem : ${institutionList}"
                             th:value="${dropDownItem.name}"
                             th:text="${dropDownItem.name}" />
         </select>
    </div>
    <div th:if="${institutionList == null or lists.isEmpty(institutionList)}">
        <div>"No Institutions were found, please create some first"</div>
    </div>
</div>

编辑:您需要向您的应用程序说明如何将表单内返回的Id (字符串类型)转换为“机构”实体。为此，您必须使用转换器。

首先，将选项的值更改为institutionId：

<div class="form-group">
 <label class="col-md-3 control-label">Institution</label>
     <div class="col-md-5">
     <div th:if="${institutionList != null and not #lists.isEmpty(institutionList)}">
         <select th:field="*{institution}">
             <option th:each="dropDownItem : ${institutionList}"
                             th:value="${dropDownItem.institutionId}"
                             th:text="${dropDownItem.name}" />
         </select>
    </div>
    <div th:if="${institutionList == null or lists.isEmpty(institutionList)}">
        <div>"No Institutions were found, please create some first"</div>
    </div>
</div>

您必须创建一个实现转换器接口的类。

@Component
public class StringToInstitution implements Converter<String, Institution> {

@Autowired
private InstitutionRepository repository; //Or the class that implments the repository.

    @Override
    public Institution convert(String arg0) {
        Long id = new Long(arg0);
        return repository.findOne(id);
    }

}