Java彈簧帖子形成一對多關係

Question

我試圖讓控件的POST形式數據對象有一對多的關係。如下面的代碼

我通知模型

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> 

當我提交表單POST到控制器，現場notification.listNotificationUser總是爲空（其他字段很好）。

我在搜索並嘗試一些解決方案，但它不工作。

Answer 1

我想你的問題是你的表單中有一個錯字：select。你正在定義2個選項塊，我想你只想定義一個空的選項。所以，應該是這樣的

<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>