無法使用Spring Boot和Thymeleaf在動態創建的表單中獲取更新值

Question

我在Thymeleaf中創建了一個動態表單，它在UI上以表格格式填充所有用戶的反饋。當控制器的GET Api被擊中時，表單首先被調用。對於相同的相關代碼如下：

allfeedbacks.html

<h2>Dynamic form</h2> 
<form action="#" th:action="@{/updatefb}" th:object="${feedbacklist}" 
    method="post"> 
    <table> 
     <tr> 
      <th>Message</th> 
      <th>Status</th> 
      <th>Comments</th> 
     </tr> 
     <tr th:each="feedback : ${feedbacklist.myfbList}"> 
      <td th:text="${feedback.message}" th:field="${feedback.message}">The 
       first name</td> 
      <td><select> 
        <option value="Pending" 
         th:selected="${feedback.status == 'Pending'}">Pending</option> 
        <option value="In Process" 
         th:selected="${feedback.status == 'In Process'}">In 
         Process</option> 
        <option value="Done" th:selected="${feedback.status == 'Done'}">Done</option> 
      </select></td> 
      <td><input type="text" placeholder="Enter Comment Here" 
       name="comments" th:text="${feedback.comment}" 
       th:field="${feedback.comment}" /></td> 
     </tr> 
    </table> 
    <button type="submit">Submit</button> 
</form> 

基本上我已經創建了兩個豆，一個是Feedback.java豆，而另一種是FeedbackList.java bean。對於相同的代碼下面給出：

Feedback.java

@Entity 
@Table(name = "feedback") 
public class Feedback implements Serializable { 

private static final long serialVersionUID = -3009157732242241606L; 

@Id 
private String id; 

public String getId() { 
    return id; 
} 

public String getMessage() { 
    return message; 
} 

public String getStatus() { 
    return status; 
} 

public String getComment() { 
    return comment; 
} 

@Column(name = "message") 
private String message; 

@Column(name = "status") 
private String status; 

@Column(name = "comment") 
private String comment; 

public Feedback() { 
} 

public Feedback(String message, String status) { 
    this.message = message; 
    this.status = status; 
    this.id = UUID.randomUUID().toString();  
} 

FeedbackList.java

public class FeedbackList { 

ArrayList<Feedback> myfbList; 

public ArrayList<Feedback> getMyfbList() { 
    return myfbList; 
    } 

public void setMyfbList(ArrayList<Feedback> myfbList) { 
    this.myfbList = myfbList; 
    } 
} 

從我的控制器類

相關代碼如下：

@RequestMapping(value = "/getAll", method = RequestMethod.GET) 
    public String getAllFeedbacks(@Valid FeedbackList feedbacklist, 
    BindingResult bindingResult, Model model) { 

    ArrayList<Feedback> fbarray = new ArrayList<>(); 
    for (Feedback fb : repository.findAll()) { 
     fbarray.add(fb); 
     } 
    feedbacklist.setMyfbList(fbarray); 
    model.addAttribute("feedback", new Feedback()); 
    model.addAttribute("feedbacklist", feedbacklist); 
    return "allfeedbacks"; 
    } 

    @RequestMapping(value = "/updatefb", method = RequestMethod.POST) 
    public String updatefbStatus(@Valid FeedbackList feedbacklist, 
    BindingResult 
    bindingResult, Model model) { 

    //feedbacklist is coming as NULL below 
    for (Feedback fb : feedbacklist.getMyfbList()) { 
     System.out.println(fb.getComment()); 
     System.out.println(fb.getMessage()); 
     System.out.println(fb.getStatus()); 
     } 
    // Code to update the database with the new status and comment would go 
    // here 
    return "result"; 
    } 

當我觸發Get請求時，表單在UI上正確呈現，但是，當我在表單中進行一些更改並提交它（POST）時，feedbacklist將作爲NULL傳入。任何人都可以請用這個指導我嗎？

Answer 1

要在帶有Thymeleaf的表單中使用列表有點棘手，您需要使用特定的語法，在這裏我向您展示一個示例。

<tr th:each="feedback : ${feedbacklist.myfbList}"> 
    <td th:field="*{myfbList[__${feedbackStat.index}__].message}">The 
     first name 
    </td> 
    ...//Same for others fields 
</tr> 

在thymeleaf你必須使用的統計對象說數組位置，你要設置的值，也因爲你必須使用「*」符號對象內的普通字段。