Thymeleaf模板和Spring Boot:从Java枚举创建单选输入 [英] Thymeleaf template and Spring Boot : Creating a radio input from Java enum

问题描述

我想从Java枚举类型源"中自动在Thymeleaf中填充无线电输入控件.我在后端使用Spring Boot.我的控制器初始化了枚举值的列表，如下所示:

I would like to populate a radio input control in a Thymeleaf automatically from a Java enum type called "source". I am using Spring Boot in the backend. My controller initialises a list of the enum values like this:

this.sourcesAsList = Arrays.asList(Source.values());
model.addAttribute("sources", sourcesAsList);

这至少在List方面有效(如我在日志输出中所见).

This works fine, at least as far as the List is concerned (as I can see in the log output).

然后，Thymeleaf模板尝试基于模型中的该属性实例化无线电控件，如下所示:

The Thymeleaf template then tries to instantiate a radio control based on this attribute in the model, like so:

<div th:each="source : ${sources}">
  <input type="radio" th:field="*{source}"  th:value="${source.value}"/><label th:text="| ${source.value} |">Should not see this !</label>
</div>

但是，当我尝试加载此页面时，出现以下错误:

However, when I try to load this page, I get the following error:

[Request processing failed; nested exception is org.thymeleaf.exceptions.TemplateInputException: An error happened during template parsing (template: "class path resource [templates/feedbackapp2.html]")] with root cause

java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'source' available as request attribute

枚举非常简单:

public enum Source {
    VALONE, VALTWO, VALTHREE, VALFOUR;

    public String getName() {
        return this.name();
    }
}

这是我第一次与Thymeleaf合作，因此我认为这只是某个地方的简单语法问题，但是即使在谷歌搜索之后，我也找不到一个有效的示例.有任何想法吗?用枚举完全可以做到这一点吗?如果没有，哪种数据类型会更合适?

It's the first time I work with Thymeleaf, so I guess it is just a simple syntax problem somewhere, but even after googling I couldn't find a working example. Any ideas? Is it possible at all to do this with an enum? If not, what kind of datatype would be more appropriate?

非常感谢.欢呼声，

马丁

推荐答案

我玩了一些，然后开始工作了.以下HTML代码段基于Enums列表正确显示了单选按钮，并且还正确地连接到了模型，因为我在控制器的POST方法中收到了选定的值:

I played around a bit more and got it working. The following HTML snippet displays the radio buttons correctly based the list of Enums and also is wired to the model correctly, in that I received the selected value in the controller's POST method:

<div th:each="source : ${sources}">
  <input name="source" type="radio" th:value="${source}"/><label for="source" th:text="| &nbsp; ${source} |">Something is wrong !</label>
</div>

有两个问题:

• 不需要访问枚举的name()属性(因此，使用$ {source}代替$ {source.name}很好)
• 代替th:field，使用输入控件的namne属性

非常感谢Periklis的评论.

Thanks a lot to Periklis for the comment.

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