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java - 无法在 null 上找到属性或字段 'index'

转载 作者：行者123 更新时间：2023-12-01 18:46:43 25 4
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我使用 Spring Boot 将文件上传到数据库并尝试将该文件显示到页面中，但出现错误。

错误:

Caused by: org.attoparser.ParseException: Exception evaluating SpringEL expression: "itrStat.index" (template: "view/user" - line 110, col 69) at org.attoparser.MarkupParser.parseDocument(MarkupParser.java:393) ~[attoparser-2.0.5.RELEASE.jar:2.0.5.RELEASE] at org.attoparser.MarkupParser.parse(MarkupParser.java:257) ~[attoparser-2.0.5.RELEASE.jar:2.0.5.RELEASE] at org.thymeleaf.templateparser.markup.AbstractMarkupTemplateParser.parse(AbstractMarkupTemplateParser.java:230) ~[thymeleaf-3.0.11.RELEASE.jar:3.0.11.RELEASE] ... 48 common frames omitted

用户.html

<body>
<div class="container-fluid">
<div class="row">
<div class="col-md-12">
<fieldset>
<legend>User Form</legend>


<div class="alert alert-success alert-dismissible" th:if="${success}">
  <button type="button" class="close" data-dismiss="alert">&times;</button>
  <strong th:if="${success}"></strong> 
</div>

<div class="alert alert-danger alert-dismissible" th:if="${errormeassage}">
  <button type="button" class="close" data-dismiss="alert">&times;</button>
  <strong th:if="${errormeassage}"></strong> 
</div>

<form action="#" th:action="@{${isAdd}?'/save':'/update'}" th:object="${user}" method="post" enctype="multipart/form-data">

    <div class="form-group">
        <input type="text" id="firstname" name="firstname" th:field="*{firstname}" placeholder="First Name" >
    </div>
    <div class="form-group">
        <input type="text" id="lastname" name="lastname" th:field="*{lastname}" placeholder="Last Name" >
    </div>

    <div class="form-group">
        <input type="text" id="email" name="email" th:field="*{email}" placeholder="Email ">
    </div>

    <div class="form-group">
        <input type="text" id="phone" name="phone" th:field="*{phone}" placeholder="Phone number" >
    </div>

    <div class="form-group" style="margin-left: 110px;">
        <input type="file" id="file" value="upload" name="file" th:field="*{file}" placeholder="Upload file " multiple="multiple">
    </div>


    <div class="form-group">
    <span th:each="file,itrStat:${userFiles}" class="imagecontainer" th:id="'imageIndex'+${itrStat.index}">
    <img alt="" src="@{'/images/'+${file.modifiedFileName}}" style="width: 80px;height: 80px;border-radius: 50%;margin-left: 10px;" class="image" th:if="${file.fileExtension!='pdf' and file.fileExtension!='xls' and file.fileExtension!='xlsx}" >
    <img alt="" src="@{'/img/pdf.png'}" style="width: 80px;height: 80px;border-radius: 50%;margin-left: 10px;" class="image" th:if="${file.fileExtension =='pdf'}" >
    <img alt="" src="@{'/img/excel.png'}" style="width: 80px;height: 80px;border-radius: 50%;margin-left: 10px;" class="image" th:if="${file.fileExtension =='xls' or file.fileExtension =='xlsx}">
    </span>
    <span class="overlay">
    <a href="#" class="icon image-confirm-delete" title="image delete" th:attr="data-id=${itrStat.index}, data-name=${file.modifiedFileName}">
    <i class="fa fa-trash" style="color: red;"></i>
    </a>
    </span>
    </div>
    <input type="hidden" th:field="*{remove}" th:id="remove">
    <input type="hidden" th:field="*{id}" id="id">
    <div class="form-group">
        <button type="submit" class="btn btn-primary" th:text="${isAd}?'Save':'Update'"></button>
    </div>
<hr>

</form>

</fieldset>
</div>

<div class="col-md-12">
<h2>ALl Users</h2>
<div style="margin-top: 20px;">

<table class="table table-striped table-bordered">
<thead>
<tr>
<th>First Name</th>
<th>Last Name</th>
<th>Email</th>
<th>Phone</th>
<th>Action</th>
</tr>
</thead>

<tbody>
<tr th:each="user:${users}">
<td th:text="${user.firstname}"></td>
<td th:text="${user.lastname}"></td>
<td th:text="${user.email}"></td>
<td th:text="${user.phone}"></td>
<td>
<a th:href="@{'/edituser/'+${user.id}}"><i class="fa fa-edit" style="font-size:48px;color:red"></i></a>
</td>
</tr>
</tbody>

</table>

</div>
</div>


</div>
</div>


<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.1.3/js/bootstrap.min.js"></script>


<script type="text/javascript">
$(function(){
    var images[];
    $('.image-confirm-delete').on('click',function(e){
        e.preventDefault();
        var id = $(this).data('id');
        var name = $(this).data('name');

        images.push(name);
        ${'#remove'}.val(images);
        $('#imageIndex'+id).hide(); 
    });

});

</script>

</body>

Controller 类

@Controller
public class FileUploadController {

    @Autowired
    private UserService userService;

    @RequestMapping("/")
    public String users(Model model,@Valid User user,BindingResult bindingResult) {
        List<User>listUser = userService.getAllUsers(); 

        model.addAttribute("users",listUser);
        model.addAttribute("user", new User());
        model.addAttribute("userFiles", new ArrayList<UserFiles>());
        model.addAttribute("isAdd", true);
        return "view/user";
    }

    @PostMapping("/save")

    public String saveUser(@ModelAttribute User user,RedirectAttributes redirectAttributes,Model model) {
         User dbUser = userService.save(user);
         if(dbUser!=null) {
             model.addAttribute("success","user is successfully saved!!");
             return "redirect:/";
         }else {
             model.addAttribute("errormeassage","user not saved,please try new one!!");
             model.addAttribute("user",user);
             return "view/user";
         }
    }

    @GetMapping(value ="/edituser/{id}")
    public String editUsers(@PathVariable Long id, Model model) {

        User user= userService.findById(id);
        //fetch file
        List<UserFiles> files = userService.findFilesByUserId(id);

        List<User>listUser = userService.getAllUsers(); 

        model.addAttribute("users",listUser);
        model.addAttribute("user", user);
        model.addAttribute("userFiles",files);
        model.addAttribute("isAdd", false);
        return "view/user";
    }


}

最佳答案

我相信th:each中定义的状态变量被称为iterStat，根据Thymeleaf documentation .

您能否尝试在代码中将“itrStat”替换为“iterStat”？

关于java - 无法在 null 上找到属性或字段 'index'，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/59819674/

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