我的html页面说我在我的页面前面使用的对象不存在。
我的html页面说我在我的页面前面使用的对象不存在。
提问于 2022-06-26 10:27:20
我试图把用户名作为参数放在我的链接中。通过jquery执行此操作唯一的问题是我得到了这个错误，请注意对象调用在span标记上是出于某种原因而工作的。我一直在看教程，但是当我试图通过$(#emailTarget).attr(“id”)获得span标记值时没有效果；并将上述id放到span标记上--它给出了未定义的值，而不是用户名。
错误堆栈
org.thymeleaf.templateparser.markup.InlinedOutputExpressionMarkupHandler.handleText(InlinedOutputExpressionMarkupHandler.java:80)
at org.attoparser.HtmlMarkupHandler.handleText(HtmlMarkupHandler.java:208)
at org.attoparser.AbstractChainedMarkupHandler.handleText(AbstractChainedMarkupHandler.java:203)
at org.attoparser.MarkupParser.parseBuffer(MarkupParser.java:557)
at org.attoparser.MarkupParser.parseDocument(MarkupParser.java:301)
... 98 more
Caused by: org.thymeleaf.exceptions.TemplateProcessingException: Exception evaluating SpringEL expression: "principal.username" (template: "index" - line 49, col 25)
at org.thymeleaf.spring5.expression.SPELVariableExpressionEvaluator.evaluate(SPELVariableExpressionEvaluator.java:292)
at org.thymeleaf.standard.expression.VariableExpression.executeVariableExpression(VariableExpression.java:166)
at org.thymeleaf.standard.expression.SimpleExpression.executeSimple(SimpleExpression.java:66)
at org.thymeleaf.standard.expression.Expression.execute(Expression.java:109)
at org.thymeleaf.standard.expression.Expression.execute(Expression.java:138)
at org.thymeleaf.standard.processor.AbstractStandardExpressionAttributeTagProcessor.doProcess(AbstractStandardExpressionAttributeTagProcessor.java:144)
at org.thymeleaf.processor.element.AbstractAttributeTagProcessor.doProcess(AbstractAttributeTagProcessor.java:74)
at org.thymeleaf.processor.element.AbstractElementTagProcessor.process(AbstractElementTagProcessor.java:95)
at org.thymeleaf.util.ProcessorConfigurationUtils$ElementTagProcessorWrapper.process(ProcessorConfigurationUtils.java:633)
at org.thymeleaf.engine.ProcessorTemplateHandler.handleOpenElement(ProcessorTemplateHandler.java:1314)
at org.thymeleaf.engine.OpenElementTag.beHandled(OpenElementTag.java:205)
at org.thymeleaf.engine.TemplateModel.process(TemplateModel.java:136)
at org.thymeleaf.engine.TemplateManager.process(TemplateManager.java:519)
at org.thymeleaf.util.LazyProcessingCharSequence.writeUnresolved(LazyProcessingCharSequence.java:85)
at org.thymeleaf.util.AbstractLazyCharSequence.write(AbstractLazyCharSequence.java:103)
at org.thymeleaf.engine.AbstractTextualTemplateEvent.writeContent(AbstractTextualTemplateEvent.java:224)
at org.thymeleaf.engine.Text.write(Text.java:78)
at org.thymeleaf.engine.OutputTemplateHandler.handleText(OutputTemplateHandler.java:71)
... 107 more
Caused by: org.springframework.expression.spel.SpelEvaluationException: EL1007E: Property or field 'username' cannot be found on null
at org.springframework.expression.spel.ast.PropertyOrFieldReference.readProperty(PropertyOrFieldReference.java:213)
at org.springframework.expression.spel.ast.PropertyOrFieldReference.getValueInternal(PropertyOrFieldReference.java:104)
at org.springframework.expression.spel.ast.PropertyOrFieldReference.access$000(PropertyOrFieldReference.java:51)我的主页
<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org"
xmlns:sec="http://www.thymeleaf.org/thymeleaf-extras-springsecurity3">
<head>
<meta charset="ISO-8859-1">
<title>Registration and Login App</title>
<link rel="stylesheet"
href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css"
integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u"
crossorigin="anonymous">
</head>
<body>
<!-- create navigation bar ( header) -->
<nav class="navbar navbar-inverse navbar-fixed-top">
<div class="container">
<div class="navbar-header">
<button type="button" class="navbar-toggle collapsed"
data-toggle="collapse" data-target="#navbar" aria-expanded="false"
aria-controls="navbar">
<span class="sr-only">Toggle navigation</span> <span
class="icon-bar"></span> <span class="icon-bar"></span> <span
class="icon-bar"></span>
</button>
<a class="navbar-brand" href="#" th:href="@{/}">Registration and
Login Module</a>
</div>
<div id="navbar" class="collapse navbar-collapse">
<ul class="nav navbar-nav">
<li sec:authorize="isAuthenticated()"><a th:href="@{/logout}">Logout</a></li>
</ul>
</div>
</div>
</nav>
<br>
<br>
<div class="container">
<h1>Registration and Login with Spring Boot, Spring Security,
Thymeleaf, Hibernate and MySQL</h1>
Welcome <span sec:authentication="principal.username"> User</span>
</div>
<a th:href="login" id="changeMe" class="btn btn-danger">Delete</a>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<script type="text/javascript" th:inline="javascript">
let email=[[${principal.username}]];
$('#changeMe').prop("href", "/delete?email="+email)
</script>
</body>
</html>回答 1
Stack Overflow用户
发布于 2022-06-26 10:37:05
如果要在链接中添加参数，请使用以下命令：<a th:href="@{/delete(email=${#authentication.principal.username})}">...</a>。这将导致像这样的uri：/delete?email=test@example.com。如果要替换路径变量- @{/delete/{email}(email=${#authentication.principal.username})}。
然而，您所面临的问题似乎更像是一个与principal连接的内部问题，即null (因此出现了错误消息)--这可能是因为您已经注销了。您可能应该检查一下，在您试图构建的链接周围是否有一个原则(例如#authentication.isAuthenticated())。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/72760752
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