Thymeleaf：单击提交按钮后显示成功消息

Question

我有一个spring-boot应用程序Thymeleaf。我有相当基本的情况。有一个表单，当用户单击“提交”按钮时，表单数据应发送到控制器，但在同一页面上应显示一条成功消息。

表格非常简单：

<form th:action="@{/suggest-event}"  method="post">
    <button type="submit" class="btn btn-primary">Submit</button>
</form>
<div th:switch="${message}">
    <div th:case="'Success'" class="alert alert-success">
        <strong>Success!</strong> Operation performed successfully.
    </div>
    <div th:case="'Failed'" class="alert alert-danger">
        <strong>Failure!</strong> Operation failed. Please try again 
    </div>
</div>

要加载表格，我在控制器中使用了以下方法：

@GetMapping("/suggest-event")
public String suggestEvent(@RequestParam(value = "message", required = false) String message) {

    model.addAttribute("message",message);
    return "/suggested-event/suggestEvent";
}

然后是回答发布请求的方法：

@PostMapping("/suggest-event")
public String receiveSuggestedEvent( RedirectAttributes redirectAttributes) {

    redirectAttributes.addAttribute("message", "Success");
    return "redirect:/suggest-event";
}

问题是，成功消息始终存在（第一次加载页面时以及在我提交表单之前）。我该如何解决？

Answer 1

You can change the code a little bit:

@GetMapping("/suggest-event")
public String suggestEvent() {
    return "/suggested-event/suggestEvent";
} 

@PostMapping("/suggest-event")
public String receiveSuggestedEvent(BindingResult result, RedirectAttributes redirectAttributes) {
    redirectAttributes.addFlashAttribute("message", "Failed");
    redirectAttributes.addFlashAttribute("alertClass", "alert-danger");
    if (result.hasErrors()) {
        return "redirect:/suggest-event";
    }
    redirectAttributes.addFlashAttribute("message", "Success");
    redirectAttributes.addFlashAttribute("alertClass", "alert-success");
    return "redirect:/suggest-event";
}

My solution to show message in html :

<div th:if="${message}" th:text="${message}" th:class="${'alert ' + alertClass}"/>

But the bottom line is replacing addFlashAttribute instead of addAttribute and removing message from @GetMapping.