javax.servlet.jsp.JspTagException：不知道如何迭代 <forEach> 中提供的“项目”

Question

What I am want to do is to add a record to a table and then to display that newly added record in a jsp page.我想要做的是将记录添加到表中，然后在 jsp 页面中显示新添加的记录。

Here is what I tried:这是我尝试过的：

Controller: Controller：

@Controller
public class UserController {
    
    @Autowired
    UserRepository userRepo;
    
    @RequestMapping("/adduser")    
    public String userform(Model m){    
        m.addAttribute("command", new Users());  
        return "adduser";
    }
    
    @RequestMapping("/saveuser")
    public String save(@ModelAttribute("user") Users user,Model model){    
        userRepo.save(user);
        model.addAttribute("user", user);
        return "forward:/user";   
    }
    
    @RequestMapping("/user")
    public String user(Model model) {
       
         return "user";
    }

And the jsp page:和 jsp 页面：

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html>
<%@ taglib prefix="spring" uri="http://www.springframework.org/tags"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<html lang="en">
<head>

<link rel="stylesheet" type="text/css"
 href="webjars/bootstrap/3.3.7/css/bootstrap.min.css" />
<c:url value="/css/main.css" var="jstlCss" />
<link href="${jstlCss}" rel="stylesheet" />

</head>
<body>
 <div class="container">
  <div class="starter-template">
   <h1>Product List</h1>
   <table
    class="table table-striped table-hover table-condensed table-bordered">
    <tr>
     <th>Id</th>
     <th>Color</th>
     <th>Gender</th>
     <th>Category</th>
    </tr>
    <c:forEach var="u" items="${user}">
     <tr>
      <td>${u.userid}</td>
      <td>${u.username}</td>
      <td>${u.userphone}</td>
      <td>${u.useremail}</td>
     </tr>
    </c:forEach>
   </table>
  </div>

 </div>

 <script type="text/javascript"
  src="webjars/bootstrap/3.3.7/js/bootstrap.min.js"></script>
</body>

</html>

Upon running the code the record is getting added successfully but It is not getting displayed instead I am getting the error mentioned in the title.运行代码后，记录已成功添加，但没有显示，而是出现标题中提到的错误。

What to do to make it work?怎么做才能让它发挥作用？

Answer 1

@RequestMapping("/user")
public List<User> user(Model model) {
     ...
     return ...;
}

${user} is the result of that method user . ${user}是该方法user的结果。

<c:forEach var="u" items="${user}">

The forEach tag requires as items something Iterable . forEach标签需要Iterable作为items 。

In fact the name should have been plural: users .事实上，这个名字应该是复数形式： users 。

You need something like你需要类似的东西

public class User {
    int userid;
    String username;
    String userphone;
    String useremail;
}

  <td>${u.userid}</td>
  <td>${u.username}</td>
  <td>${u.userphone}</td>
  <td>${u.useremail}</td>

javax.servlet.jsp.JspTagException：不知道如何迭代 <forEach> 中提供的“项目”

问题描述

1 个解决方案

解决方案1
0 2022-08-14 07:09:26

javax.servlet.jsp.JspTagException：不知道如何迭代 &lt;forEach&gt; 中提供的“项目”

问题描述

1 个解决方案

解决方案1 0 2022-08-14 07:09:26

javax.servlet.jsp.JspTagException：不知道如何迭代 <forEach> 中提供的“项目”

解决方案1
0 2022-08-14 07:09:26