@PostMapping 状态 500 错误 TemplateProcessingException 和 IllegalStatementException

Question

我正在尝试使用 Spring Boot 创建一个简单的页面，它只显示用户输入。但是当我转到 @PostMapping 路径时，它会给我一个状态 500 错误，但有以下例外：

org.thymeleaf.exceptions.TemplateProcessingException：处理器执行期间出错 'org.thymeleaf.spring5.processor.SpringInputGeneralFieldTagProcessor'（模板：“greeting.html”- 第 12 行，第 31 栏）

2021-10-18 19:53:24.476 错误 9332 --- [nio-8080-exec-4] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] throw exception [Request processing failed;嵌套异常是 org.thymeleaf.exceptions.TemplateProcessingException：执行处理器 'org.thymeleaf.spring5.processor.SpringInputGeneralFieldTagProcessor' 期间出错（模板：“greeting.html” - 第 12 行，第 31 列）]，根本原因是

java.lang.IllegalStateException：bean 名称 'greeting' 的 BindingResult 和普通目标对象都不能用作请求属性

这是我的模型：

package com.example.springplay;


public class Greeting {

    private long id;
    private String content;

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public String getContent() {
        return content;
    }

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

}

这是我的控制器：

package com.example.springplay;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.*;

@Controller
public class MainController {

//    @RequestMapping(value="/greeting", method = RequestMethod.GET)
    @GetMapping("/greeting")
    public String greeting(@RequestParam(name="name", required=false, defaultValue="World") String name, Model model) {
        model.addAttribute("name", name);
        return "greeting.html";
    }

    @PostMapping("/greeting")
    public String greetingSubmit(@ModelAttribute Greeting greeting, Model model) {
        model.addAttribute("greeting", greeting);
        return "result.html";
    }
}

这是我的 HTML 页面： greeting.html


<!DOCTYPE HTML>
<html xmlns:th="https://www.thymeleaf.org">
<head>
    <title>Getting Started: Handling Form Submission</title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
</head>
<body>
<h1>Form</h1>
<p th:text="${name}"></p>
<form action="#" th:action="@{/greeting}" th:object="${greeting}" method="post">
    <p>Id: <input type="text" th:field="*{id}" /></p>
    <p>Message: <input type="text" th:field="*{content}" /></p>
<!--    <p><input type="submit" value="Submit" /> <input type="reset" value="Reset" /></p>-->
    <button type="submit">Submit Your Post</button>
</form>
</body>
</html>

index.html

<!DOCTYPE HTML>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <title>Getting Started: Serving Web Content</title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
</head>
<body>
<p>Get your greeting <a th:href="@{/greeting}">here</a></p>
</body>
</html>

result.html

<!DOCTYPE HTML>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <title>Getting Started: Serving Web Content</title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
</head>
<body>
<h1>Result</h1>
<p th:text="'id: ' + ${greeting.id}" />
<p th:text="'content: ' + ${greeting.content}" />
<a href="/greeting">Submit another message</a>

</body>
</html>

编辑：我通过将参数“Greeting greeting”添加到 public String greeting() 来修复它，所以它就像

@GetMapping("/greeting")
    public String greeting(@RequestParam(name="name", required=false, defaultValue="World") String name, Greeting greeting, Model model) {
        model.addAttribute("name", name);
        return "greeting.html";
    }

虽然我不知道为什么会这样，希望有人能解释一下

Answer 1

你能试试吗：

 @GetMapping("/greeting")
    public String greeting(@RequestParam(name="name", required=false, defaultValue="World") String name, Greeting greeting, Model model) {
        model.addAttribute("name", name);
        model.addAttribute("greeting", new Greeting());
        return "greeting.html";
    }

@PostMapping 状态 500 错误 TemplateProcessingException 和 IllegalStatementException

@PostMapping status 500 Error TemplateProcessingException and IllegalStatementException

spring

thymeleaf

request-mapping