Thymeleaf和SpringBoot的下拉列表

Question

我有一个在HTML上使用Thymeleaf的Spring Boot 1.3应用程序.我有用户页面,当我编辑它们时,我希望从列表中选择用户机构.我让窗口正确显示所有内容,但是当我选择机构时,控制器不显示所选值.

这是我的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获取User对象时,该机构为null.

编辑我使用Sergios建议select th:field="${user.institution}" 以及使用 select th:field="*{institution}"

但这给了我一个错误:

org.springframework.validation.BeanPropertyBindingResult:1 errors字段'institution'上对象'us​​er'的字段错误:被拒绝的值[com.security.Institution@3e3945d2]; 代码[typeMismatch.user.institution,typeMismatch.institution,typeMismatch.com..security.Institution,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable:codes [user.institution,institution]; 参数[]; 默认消息[机构]]; 默认消息[无法将类型'java.lang.String'的属性值转换为属性'institution'所需的类型'com.security.Institution'; 嵌套异常是org.springframework.core.convert.ConversionFailedException:无法从类型java.lang.String转换为类型java.lang.Long,值为'com.security.Institution@3e3945d2'; 嵌套异常是java.lang.NumberFormatException:对于输入字符串:"com .security.Institution @ 3e3945d2"]

不确定我是否正确阅读,但这是否意味着Thymeleaf试图将Institution.name传递给user.institution字段？

任何人都可以就如何做到这一点提出任何建议吗？

Answer 1

您已经忘记指明必须采用所选值的字段:

示例:I supousse User类具有INSTIT的属性.

<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>

更多信息:http://www.thymeleaf.org/doc/tutorials/2.1/thymeleafspring.html#dropdownlist-selectors

编辑:您需要向您的应用程序指明如何将表单(字符串类型)中返回的Insitution ID转换为Institution实体.为此你必须使用转换器.

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Converter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);
    }

}