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Spring boot + thymeleaf in IntelliJ: cannot resolve vars

 原文  2016-08-02 01:44:31  5   13    java/ spring/ web/ intellij-idea/ thymeleaf

Question

I'm writing a short web form application using spring boot and thymeleaf on IntelliJ, but it seems that in the html file, all fields in the model cannot be resolved. Here is my code:

Controller class:

@Controller
public class IndexController{

    @RequestMapping(value = "/", method = RequestMethod.GET)
    public String index(){
        return "index";
    }

    @RequestMapping(value="/", method = RequestMethod.POST)
    public String addNewPost(@Valid Post post, BindingResult bindingResult, Model model){
        if(bindingResult.hasErrors()){
            return "index";
        }
        model.addAttribute("title",post.getTitle());
        model.addAttribute("content",post.getContent());
        return "hello";
    }
}

Model Class:

public class Post {

    @Size(min=4, max=35)
    private String title;

    @Size(min=30, max=1000)
    private String content;

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }
}

Then is the index.html:

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head lang="en">

    <title>Spring Framework Leo</title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
</head>
<body>

<h3>Spring Boot and Thymeleaf</h3>


    <form action="#" th:action="@{/}"  th:object="${post}" method="post">
        <table>
            <tr>
                <td>Title:</td>
                <td><input type="text" th:field="*{title}" /></td>
                <td th:if="${#fields.hasErrors('title')}" th:errors="*{title}">Title error message</td>
            </tr>
            <tr>
                <td>Content:</td>
                <td><input type="text" th:field="*{content}" /></td>
                <td th:if="${#fields.hasErrors('content')}" th:errors="*{content}">Content error message</td>
            </tr>
            <tr>
                <td><button type="submit">Submit post</button></td>
            </tr>
        </table>
    </form>

There are always red lines under "post", "title" and "content", but I don't know how to solve it. Is it a problem of IntelliJ or just a problem of my code?

13 answers

solution1
 49  2019-05-10 16:21:49

Update

TL;DR: skip to accepted answer below: https://stackoverflow.com/a/44804086/474034

As mentioned in the comments by multiple people, this solution is not correct. The Thymeleaf documentation (see http://thymeleaf.org/doc/tutorials/3.0/usingthymeleaf.html ), have in all their examples a version with www. included:

<html xmlns:th="http://www.thymeleaf.org">

See also the Standard-Dialect.xml on Github, which declares namespace-uri as:

namespace-uri="http://www.thymeleaf.org"

Original Answer

I had two different portions of code: the first was showing the error and the second was not doing it. I observed that there is a difference in the xmlns:th attribute.

First Page: Not working!

<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:th="http://www.thymeleaf.org">

Second Page: Working!

<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:th="http://thymeleaf.org">

I removed the www. and it works for me!

solution2
 24 ACCPTED  2017-06-28 13:35:48

Prerequisites

  • Thymeleaf plugin is installed

  • The html element has an XML namespace declaration for th that is set to http://www.thymeleaf.org (with www. ), for example: 

     <html xmlns:th="http://www.thymeleaf.org">

IntelliJ version >= 2017.3

Detection should work automatically. However, some people complain that it still does not work for them), the issue IDEA-132738 should be fixed (@FloatOverflow: "I confirm that in version 2017.3 build 25.Oct.2017 the problem has been solved"):

Status 2017.3

Support for Spring Boot autoconfigured MVC applications is complete, all bundled autoconfiguration view types are supported.

Fix versions: 2017.3

If variables are not automatically detected you can still add the @thymesVar annotation as shown below.

IntelliJ version < 2017.3

It is, as Andrew wrote , a known error IDEA-132738 . There is a workaround how to get rid of the error marks in the IDE. IntelliJ also supports the semi-automatic generation of the below mentioned code:

You can use Alt + Enter shortcut to invoke intention "Declare external variable in comment annotation" in order to get rid of "unresolved model attribute" in your views.

Add the following code to your html file:

<!--/* Workaround for bug https://youtrack.jetbrains.com/issue/IDEA-132738 -->
    <!--@thymesVar id="post" type="your.package.Post"-->
    <!--@thymesVar id="title" type="String"-->
    <!--@thymesVar id="content" type="String"-->
<!--*/-->

If you use extensions objects constructed automatically by ThymeLeaf, such as #temporals from thymeleaf-extras-java8time for conversion of java.time objects:

<span th:text="${#temporals.format(person.birthDate,'yyyy-MM-dd')}"></span>

and IntelliJ cannot resolve them, use similar code, and just add # in front of the object name:

<!--@thymesVar id="#temporals" type="org.thymeleaf.extras.java8time.expression.Temporals"-->

solution3
 16  2016-08-02 12:35:18

This is a problem with IntelliJ: IDEA-132738 .

Basically IntelliJ is unable to locate the model variables when Spring Boot has been used to autoconfigure everything.

solution4
 13  2017-12-15 08:35:08

I want to add one more thing. As stated above, the issue has been fixed in IntelliJ 2017.3 . I can also confirm this.

However, I noticed that this is only true if you define all your attributes directly inside the responsible controller function, like eg this:

@RequestMapping(value = "/userinput")
public String showUserForm(Model model){
    model.addAttribute("method", "post");
    model.addAttribute("user", new User());
    return "userform";
}

If you are using a sub-function in which you define the model attributes (see Example below), IntelliJ can still not find the attributes in the HTML template.

Example :

@RequestMapping(value = "/userinput")
public String showUserForm(Model model){
    return doIt(model);
}

private String doIt(Model model) {
    model.addAttribute("method", "post");
    model.addAttribute("user", new User());
    return "userform";
}

So, always make sure you put your code directly inside the view function!

solution5
 5  2019-04-01 14:05:05

Manually enabling it, worked for me in Intellij 2018.1.6 Ultimate Edition. Steps followed

  1. Open the Project tool window (eg View | Tool Windows | Project).

  2. Right-click the project or the module folder and select Add Framework Support.

  3. In the left-hand pane of the Add Frameworks Support dialog that opens, select the Thymeleaf checkbox.

Official reference : https://www.jetbrains.com/help/idea/thymeleaf.html#0c8052be

solution6
 1  2018-05-03 11:58:56

In my case the problem was that I had the following in my application.properties:

spring.thymeleaf.prefix=file:src/main/resources/templates/

spring.thymeleaf.cache=false

Once I removed these properties, the spring mvc mappings are detected by Intellij again (in the Ultimate version, I'm using 2018.1). Also the thymeleaf objects are working now.

I used these properties to support fast development where a refresh would reload the thymeleaf template files.

To solve this issue, I use the following -D option in my run configuration of my spring boot application to tell spring boot where my property files are during development:

-Dspring.config.location=/dev/application/conf/application.properties

solution7
 1  2019-03-28 10:50:16

还有一种更有趣的情况，如果您不直接从控制器返回对象，Intellij 将无法识别该变量，但她仍然可以工作

solution8
 1  2021-06-16 21:01:19

This problem comes from thymeleaf web link.

The problem: xmlns:th="http://www.thymeleaf.org"

这是问题链接：

这是错误区域：

The solution: xmlns:th="http://thymeleaf.org"

解决方案链接

错误消失了

solution9
 0  2021-08-30 15:10:06

For those who come from ReactJS and want to use Springboot as a backend.

I forgot to add html boilerplate code in the html, that's why I'm seeing this error. don't forget adding boilerplate code.

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>HTML 5 Boilerplate</title>
    <link rel="stylesheet" href="style.css">
  </head>
  <body>
    <script src="index.js"></script>
  </body>
</html>

solution10
 0  2021-09-10 06:18:31

This was happening to me on Ultimate 2021.2.1.

In one @GetMapping method, I used @ModelAttribute('transactionForm') . The Thymeleaf page for that method didn't have errors.

But in another @GetMapping method, I didn't use @ModelAttribute('newCustomerForm') . The Thymeleaf page for that method had the errors. When I added the @ModelAttribute to the method, the errors went away. And when I took it out, the errors came back.

I know Spring MVC doesn't require the @ModelAttribute if the name of the model is the same as the class name. So I shouldn't have to do this, and I'm only doing this to appease the IDE.

solution11
 0  2022-02-09 00:09:10

I had the same problem and fixed it (ultimate 2021.3.2). Intellij has a hard time guessing the type of the attribute(s).

Keep www in the namespace xmlns:th="http://www.thymeleaf.org" otherwise Intellij won't parse thymeleaf tags

If you initialize one model in a controler,

  • don't use a method's return, declare a variable

    String titre=post.getTitle(); model.addAttribute("title",titre);

  • don't add attributes through sub methods, keep it in the main block

    @GetMapping("/book") public String ver(Model model) { ... model.addAttribute("title", title); return "frontpage"; }

  • and don't use complex operator like the ternary one

    model.addAttribute("titles", titles.size() > 0 ? titles : null);

If you initialize 2 or 3 models in you controler, don't push null values

model.addAttribute("employees", null);

solution12
 0  2022-04-25 15:14:00

I was resolve like following click Alt + Enter

Lets try it!!!

在此处输入图像描述

solution13
 -1  2018-04-06 08:54:21

This feature is supported in the Ultimate edition only.

Click here for more details

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