无法迭代jstl jsp中的对象列表

Question

I am creating web app using spring boot and jsp. 我正在使用Spring Boot和JSP创建Web应用程序。 The JSP page is just showing data which i am showing set in firm object. JSP页面仅显示我要显示在固定对象中的数据。 I am trying to fetch values from java object in c:foreach but every time getting exception every time i hit localhost to open user page. 我试图从c：foreach中的java对象获取值，但是每次我每次访问localhost打开用户页面时都遇到异常。

javax.el.PropertyNotFoundException: Property [text] not found on type [java.lang.String] javax.el.PropertyNotFoundException：在类型[java.lang.String]上找不到属性[text]

Controller class 控制器类

import java.util.ArrayList;
import java.util.List;

import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.servlet.ModelAndView;

import com.model.ListModel;
import com.model.User;

@Controller
public class UserController {

     @RequestMapping(value = "/user", method = RequestMethod.GET)
     public ModelAndView user() {
        User user = new User();
        List<ListModel> modelList = new ArrayList<>();
        ListModel ls = new ListModel();
        ls.setText("s1");
        ls.setSelcted(true);
        modelList.add(ls);
        ls = new ListModel();
        ls.setText("s2");
        ls.setSelcted(true);
        modelList.add(ls);
        user.setFavoriteFrameworks(modelList);
        ModelAndView modelAndView = new ModelAndView("user", "command", user);
        return modelAndView;
    }

@RequestMapping(value = "/users", method = RequestMethod.POST)
public String addUser(@ModelAttribute("favoriteFrameworks") User 
user,BindingResult bindingResul, ModelMap model) {
    model.addAttribute("username", user.getUsername());
    model.addAttribute("password", user.getPassword());
    model.addAttribute("address", user.getAddress());
    model.addAttribute("receivePaper", user.isReceivePaper());
    List<ListModel> modelList = user.getFavoriteFrameworks();
    for(ListModel ll : modelList){
        System.out.println(ll.getText());
    }
    model.addAttribute("favoriteFrameworks", 
user.getFavoriteFrameworks());
    return "users";
}

    @ModelAttribute("webFrameworkList")
    public List<ListModel> getWebFrameworkList() {
        return getModel();
    }

    private List<ListModel> getModel() {

        List<ListModel> modelList = new ArrayList<>();
        ListModel ls = new ListModel();
        ls.setText("s1");
        ls.setSelcted(true);
        modelList.add(ls);
        ls = new ListModel();
        ls.setText("s2");
        ls.setSelcted(true);
        modelList.add(ls);
        ls = new ListModel();
        ls.setText("s3");
        ls.setSelcted(true);
        modelList.add(ls);
        ls = new ListModel();
        ls.setText("s4");
        ls.setSelcted(true);
        modelList.add(ls);
        return modelList;
    }
}

JSP page view JSP页面视图

<%@taglib uri = "http://www.springframework.org/tags/form" prefix = "form"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<html>
<head>
  <title>Spring MVC Form Handling</title>
</head>
<body>

  <h2>User Information</h2>
  <form:form method = "POST" action = "/users">
     <table>
        <tr>
           <td><form:label path = "username">User Name</form:label></td>
           <td><form:input path = "username" /></td>
        </tr>
        <tr>
           <td><form:label path = "password">Age</form:label></td>
           <td><form:input path = "password" /></td>
        </tr>  
        <tr>
           <td><form:label path = "address">Address</form:label></td>
           <td><form:textarea path = "address" rows = "5" cols = "30" /></td>
        </tr>  
        <tr>
           <td><form:label path = "receivePaper">Subscribe Newsletter</form:label></td>
           <td><form:checkbox path = "receivePaper" /></td>
        </tr> 
        <tr>
           <td><form:label path = "favoriteFrameworks">Favorite Web Frameworks</form:label></td>
          <!--  <td><form:checkboxes items = "${webFrameworkList}" path = "favoriteFrameworks" /></td>  -->

                <c:forEach items="${webFrameworkList} " var="department">
                            <tr><td>${department.text}</td></tr> 
                        <!--    <tr><td><form:checkbox
                                    path="favoriteFrameworks" value='${department.text}' checked='${department.selcted}' />${department.text}</td></tr>  -->

                </c:forEach>

        </tr> 
        <tr>
           <td colspan = "2">
              <input type = "submit" value = "Submit"/>
           </td>
        </tr>
     </table>  
  </form:form>
 </body>
</html>

Why am I getting this error? 为什么会出现此错误？

Answer 1

It looks like you have incorrectly set webFrameworkList attribute you're trying to iterate over. 看来您尝试迭代的webFrameworkList属性设置不正确。 The exception is telling you that it can't find a getText() method on the department var defined in the jsp (which, according to the exception message, is a String and not your ListModel ). 异常告诉您无法在jsp中定义的department var上找到getText()方法（根据异常消息，该方法是String而不是ListModel ）。

Consider eliminating the annotated @ModelAttribute method and instead setting the model attribute in the ModelAndView user() method. 考虑消除带注释的@ModelAttribute方法，而在ModelAndView user()方法中设置模型属性。

...

ModelAndView modelAndView = new ModelAndView("user", "command", user);
modelAndView.addObject("webFrameworkList", getModel());

return modelAndView;

Edit 编辑

Regarding the comment about form submission, the post handler method addUser specifies 关于表单提交的评论，后处理程序方法addUser指定

@ModelAttribute("favoriteFrameworks") User

but the form doesn't have a modelAttribute defined. 但是表单没有定义modelAttribute 。

So there are two problems here. 因此，这里有两个问题。

favoriteFrameworks is a List , not a User . favoriteFrameworks是一个List ，而不是User 。
The form doesn't specify it anyway 表单仍然没有指定

Change the post handler's signature to 将帖子处理程序的签名更改为

public String addUser(@ModelAttribute("user") User user,BindingResult bindingResul, ModelMap model)

Then change the form opening tag to 然后将form开始标签更改为

<form:form method = "POST" action = "/users" model attribute="user">

无法迭代jstl jsp中的对象列表

问题描述

1 个解决方案

解决方案1
0 2018-07-11 21:05:24

无法迭代jstl jsp中的对象列表

问题描述

1 个解决方案

解决方案1 0 2018-07-11 21:05:24

解决方案1
0 2018-07-11 21:05:24