Spring Boot model.addAttribute - 如何让消息正确显示？

Question

I found the following example to walk myself through a part of SpringBoot: found here我找到了以下示例来引导自己完成 SpringBoot 的一部分：在此处找到

The example works without an error, but I am not able to wrap my head around why the addAttribute will not display the changed message, but rather returns only "message" as a string.该示例可以正常运行，但我无法理解为什么 addAttribute 不会显示已更改的消息，而是仅将“消息”作为字符串返回。

UPDATE The use of the @Controller annotation leads to an inability to execute for the project, and as a resolution, it needs to be @RestController . UPDATE @Controller注解的使用导致项目无法执行，作为解决方案，需要@RestController 。 I'm not sure if that bears any significance for the general issue.我不确定这对一般问题是否有任何意义。

This is the controller code:这是 controller 代码：

    package com.example.MySecondSpringBootProject.Controller;

import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;


@RestController
public class HomeController {

    @GetMapping("/")
    public String hello(){
        return "hello";
    }
    @GetMapping("/message")
    public String message(Model model) {
        model.addAttribute("message", "This is a custom message");
        return "message";
    }
}

This is the message html page:这是消息html页面：

    <!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>Spring Demo Project</title>
</head>
<body>
    <h1 th:text="${message}"></h1>
</body>
</html>

And this is the output from "/message" on the locahost:这是本地主机上“/message”的 output：

I've looked at various implementations of addAttribute here and they all use an incoming value from a frontend to assign a value to said attribute, which makes sense for this endpoint, but in this case, the frontend is pulling the value passed into it from the second parameter of the method - at least it should.我在这里查看了 addAttribute 的各种实现，它们都使用来自前端的传入值来为所述属性分配一个值，这对该端点有意义，但在这种情况下，前端正在从中提取传递给它的值该方法的第二个参数 - 至少应该如此。

I've tried this, to no effect:我试过这个，没有效果：

 @RequestMapping("/message")
public String message(Model model, @RequestParam(value="message") String message) {
    model.addAttribute("message", "This is a custom message");
    return "message";
}

Passing a second argument in the method, also to no effect, it just returns the "message" string:在方法中传递第二个参数，同样没有效果，它只返回“消息”字符串：

@GetMapping("/message")
public String message(Model model, String str) {
    model.addAttribute("message", "This is a custom message");
    return "message";
}

I will keep looking into it, but my head is going into circles at this point, or I'm just not quite understanding something about the model.addAttribute concept.我会继续研究它，但此时我的脑袋开始转圈，或者我只是不太了解 model.addAttribute 概念。

Thank you in advance!先感谢您！

Answer 1

try this solution:试试这个解决方案：

@GetMapping("/message")
public String message(Model model) {
    String msg = "This is a custom message" ;
    model.addAttribute("msg", msg);
    return "message";
}

for the view:对于视图：

<h2 th:text="${msg}" align="center"></h2>

i hope this help you我希望这对你有帮助

Answer 2

You are returning the string "message" try returning return model.addAtribute("message","this is custom message");您正在返回字符串“message”尝试返回return model.addAtribute("message","this is custom message"); . .

Spring Boot model.addAttribute - 如何让消息正确显示？

问题描述

2 个解决方案

解决方案1
1 已采纳 2022-11-14 04:30:45

解决方案2
1 2022-11-14 04:40:23

Spring Boot model.addAttribute - 如何让消息正确显示？

问题描述

2 个解决方案

解决方案1 1 已采纳 2022-11-14 04:30:45

解决方案2 1 2022-11-14 04:40:23

解决方案1
1 已采纳 2022-11-14 04:30:45

解决方案2
1 2022-11-14 04:40:23