Spring - BindingResult 和 bean 名称“form”的普通目标对象都不能作为请求属性

问题描述 投票：0回答：1

我正在使用 Java 和 Spring 使用 Thymeleaf。

我创建了一个带有几个输入的表单，IntelliJ 抱怨它无法解析 Thymeleaf 对象属性。当我尝试加载网站时，它给出错误代码 500。

我在网上尝试了很多常见问题，例如 HTML 标签中缺少 xmlns:th，我不断地尝试更改旧版本中的微小内容。不太确定该做什么了，我已经到了互联网的尽头又回来了，但也许我很愚蠢。 这是堆栈：

2023-09-22T21:20:01.188+01:00 ERROR 15828 --- [nio-8080-exec-3] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed: org.thymeleaf.exceptions.TemplateInputException: An error happened during template parsing (template: "class path resource [templates/index.html]")] with root cause

java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'form' available as request attribute
    at org.springframework.web.servlet.support.BindStatus.<init>(BindStatus.java:153) ~[spring-webmvc-6.0.12.jar:6.0.12]
    at org.springframework.web.servlet.support.RequestContext.getBindStatus(RequestContext.java:926) ~[spring-webmvc-6.0.12.jar:6.0.12]
    at org.thymeleaf.spring6.context.webmvc.SpringWebMvcThymeleafRequestContext.getBindStatus(SpringWebMvcThymeleafRequestContext.java:232) ~[thymeleaf-spring6-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.thymeleaf.spring6.util.FieldUtils.getBindStatusFromParsedExpression(FieldUtils.java:306) ~[thymeleaf-spring6-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.thymeleaf.spring6.util.FieldUtils.getBindStatus(FieldUtils.java:253) ~[thymeleaf-spring6-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.thymeleaf.spring6.util.FieldUtils.getBindStatus(FieldUtils.java:227) ~[thymeleaf-spring6-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.thymeleaf.spring6.processor.AbstractSpringFieldTagProcessor.doProcess(AbstractSpringFieldTagProcessor.java:174) ~[thymeleaf-spring6-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.thymeleaf.processor.element.AbstractAttributeTagProcessor.doProcess(AbstractAttributeTagProcessor.java:74) ~[thymeleaf-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.thymeleaf.processor.element.AbstractElementTagProcessor.process(AbstractElementTagProcessor.java:95) ~[thymeleaf-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.thymeleaf.util.ProcessorConfigurationUtils$ElementTagProcessorWrapper.process(ProcessorConfigurationUtils.java:633) ~[thymeleaf-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.thymeleaf.engine.ProcessorTemplateHandler.handleStandaloneElement(ProcessorTemplateHandler.java:918) ~[thymeleaf-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.thymeleaf.engine.TemplateHandlerAdapterMarkupHandler.handleStandaloneElementEnd(TemplateHandlerAdapterMarkupHandler.java:260) ~[thymeleaf-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.thymeleaf.templateparser.markup.InlinedOutputExpressionMarkupHandler$InlineMarkupAdapterPreProcessorHandler.handleStandaloneElementEnd(InlinedOutputExpressionMarkupHandler.java:256) ~[thymeleaf-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.thymeleaf.standard.inline.OutputExpressionInlinePreProcessorHandler.handleStandaloneElementEnd(OutputExpressionInlinePreProcessorHandler.java:169) ~[thymeleaf-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.thymeleaf.templateparser.markup.InlinedOutputExpressionMarkupHandler.handleStandaloneElementEnd(InlinedOutputExpressionMarkupHandler.java:104) ~[thymeleaf-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.attoparser.HtmlVoidElement.handleOpenElementEnd(HtmlVoidElement.java:92) ~[attoparser-2.0.7.RELEASE.jar:2.0.7.RELEASE]
    at org.attoparser.HtmlMarkupHandler.handleOpenElementEnd(HtmlMarkupHandler.java:297) ~[attoparser-2.0.7.RELEASE.jar:2.0.7.RELEASE]
    at org.attoparser.MarkupEventProcessorHandler.handleOpenElementEnd(MarkupEventProcessorHandler.java:402) ~[attoparser-2.0.7.RELEASE.jar:2.0.7.RELEASE]
    at org.attoparser.ParsingElementMarkupUtil.parseOpenElement(ParsingElementMarkupUtil.java:159) ~[attoparser-2.0.7.RELEASE.jar:2.0.7.RELEASE]
    at org.attoparser.MarkupParser.parseBuffer(MarkupParser.java:710) ~[attoparser-2.0.7.RELEASE.jar:2.0.7.RELEASE]
    at org.attoparser.MarkupParser.parseDocument(MarkupParser.java:301) ~[attoparser-2.0.7.RELEASE.jar:2.0.7.RELEASE]
    at org.attoparser.MarkupParser.parse(MarkupParser.java:257) ~[attoparser-2.0.7.RELEASE.jar:2.0.7.RELEASE]
    at org.thymeleaf.templateparser.markup.AbstractMarkupTemplateParser.parse(AbstractMarkupTemplateParser.java:230) ~[thymeleaf-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.thymeleaf.templateparser.markup.AbstractMarkupTemplateParser.parseStandalone(AbstractMarkupTemplateParser.java:100) ~[thymeleaf-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.thymeleaf.engine.TemplateManager.parseAndProcess(TemplateManager.java:666) ~[thymeleaf-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1103) ~[thymeleaf-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1077) ~[thymeleaf-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.thymeleaf.spring6.view.ThymeleafView.renderFragment(ThymeleafView.java:372) ~[thymeleaf-spring6-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.thymeleaf.spring6.view.ThymeleafView.render(ThymeleafView.java:192) ~[thymeleaf-spring6-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1415) ~[spring-webmvc-6.0.12.jar:6.0.12]
    at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1159) ~[spring-webmvc-6.0.12.jar:6.0.12]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1098) ~[spring-webmvc-6.0.12.jar:6.0.12]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:974) ~[spring-webmvc-6.0.12.jar:6.0.12]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1011) ~[spring-webmvc-6.0.12.jar:6.0.12]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:903) ~[spring-webmvc-6.0.12.jar:6.0.12]
    at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:564) ~[tomcat-embed-core-10.1.13.jar:6.0]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:885) ~[spring-webmvc-6.0.12.jar:6.0.12]
    at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:658) ~[tomcat-embed-core-10.1.13.jar:6.0]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:205) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:149) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51) ~[tomcat-embed-websocket-10.1.13.jar:10.1.13]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:174) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:149) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-6.0.12.jar:6.0.12]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.0.12.jar:6.0.12]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:174) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:149) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-6.0.12.jar:6.0.12]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.0.12.jar:6.0.12]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:174) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:149) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-6.0.12.jar:6.0.12]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.0.12.jar:6.0.12]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:174) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:149) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:167) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:90) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:482) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:115) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:93) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:341) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:391) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:63) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:894) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1740) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-10.1.13.jar:10.1.13]
    at java.base/java.lang.Thread.run(Thread.java:833) ~[na:na]

正如我所见，它说很难在控制器中的表单和映射之间进行链接。 我已经尝试过使用控制器更改一些内容，例如添加 

model.addAttribute("form", new Form());
但这并不能解决问题。我有
@ModelAttribute("form")
。

我还尝试寻找要在 Form.java 中添加的注释，这也是我需要绑定的对象。

这是我模板中的 HTML，index.html。这就是 IntelliJ 在 

${form}
下面有橙色呻吟线和在下面有红色呻吟线的地方； 
*{name}
，
*{email}
，
*{message}
。我尝试过一些事情，例如使用 
<form:form hidde..
以及 
th:
，不太确定问题是否在这里。

    <div class="grid-item" id="content-box">
        <noscript><p style="color: #ffffff; text-align: center">You do not have Javascript enabled. It is required for this website to work correctly.</p></noscript>
        <div id="content"></div>
        <form hidden id="form" th:action="@{/form}" th:object="${form}">
            <p class="text">Name: <input type="text" th:field="*{name}"></p>
            <p class="text">Email: <input type="text" th:field="*{email}"></p>
            <p class="text">Message: <input type="text" th:field="*{message}"></p>
        </form>
    </div>

正如之前对我的 FormController 所说，我改变了一些东西，我尝试从 

PostMapping()
切换到 
RequestMapping()
，然后在其中添加 
modelAttribute="form"
，但这也不起作用。 我还添加了 
model.addAttribute("form", new Form())
，因为有人说修复了它，但它仍然在发生。

@Controller
public class FormController {
    @PostMapping("/form")
    public void formReceived(@ModelAttribute("form") Form form, Model model) {
        model.addAttribute("form", new Form());
        System.out.println(form.getName());
    }
}

最后我能想到的最后一个链接是我的表单类，但是我不知道它可能出问题在哪里，我也尝试搜索注释，看看是否有任何我可以添加的内容，但我还没有找到一个。

public class Form {
    private String name;
    private String email;
    private String message;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }
}

所以是的..我不知道该去哪里，这里有很多类似的东西，但它们都是 2016 年的，并且有大约 1 个响应，这就是我得到许多这些小修复的地方，但它们还没有不起作用，我怀疑他们真的很老了。

java html spring-boot spring-mvc thymeleaf
1个回答
0
投票

我想通了。我有一个单独的 FormController 类，其中包含我的映射， 在网站所在的“/”端点的主映射中，我添加了：

model.addAttribute("form", new Form());
并将其公开，就像在 FormController 中一样，它没有公开它。

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