Java spring post形成一对多关系

Question

我正在尝试获取对象控制器上的 POST 表单数据具有一对多关系。就像下面的代码

我的通知模型

private long id;
@NotBlank(message = ERROR.NOT_EMPTY)
private String title;
@NotBlank(message = ERROR.NOT_EMPTY)
private String content;
// One Notification has many User
private List<NotificationUser> listNotificationUser;;

// Getter and setter method

我的控制器

@RequestMapping(value = "notification/add", method = RequestMethod.GET)
public String create(ModelMap model) {
    ArrayList<User> listUser = userService.getAllUsername();
    model.put("user", listUser);
    model.addAttribute("notification", new Notification());

    return "notification/add";

}
@RequestMapping(value = "notification/add", method = RequestMethod.POST)
public String create(ModelMap model, HttpServletRequest request,
        @Valid @ModelAttribute(value = "notification") Notification notification, BindingResult bindingResult) {
    ....
}

我的.jsp

<form:form method="POST" action="add" name="addForm" commandName="notification">
        <!-- Other input -->
        <form:select path="listNotificationUser" multiple="multiple" id="name" name="itemValue">
          <form:options />
          <form:options items="${user}" itemValue="id" itemLabel="name" />
        </form:select>
      <!-- Other input -->
      </form:form>

当我向控制器提交 POST 表单时，字段 notification.listNotificationUser 始终为空（其他字段很好）。

我正在搜索并尝试一些解决方案，但它不起作用。

Answer 1

我猜你的问题是你的表单中有错字：select。您正在定义 2 个选项块，我猜您只想定义一个空选项。所以应该是这样的

<form:select path="listNotificationUser" multiple="multiple" id="name" name="itemValue">
     <!-- Some value you can identify as empty option--> 
     <form:option value="0" label="--Options--"/> 
     <form:options items="${user}" itemValue="id" itemLabel="name" />
</form:select>