Thymeleaf - 如何在 Thymeleaf 标签“th:if”中将字符串与 html 中的请求参数进行比较？
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Thymeleaf - How to compare string with request parameter in html in Thymeleaf tag "th:if"?
提问by user3515080
How to compare string with request parameter in html in Thymeleaf tag "th:if" ? right now i am using this
如何在 Thymeleaf 标签“th:if”中将字符串与 html 中的请求参数进行比较？现在我正在使用这个
<div class="error" th:if="${param.error == 'badCredentialsException'}" th:with="errorMsg=#{login.badCredentials}">
<p class="errorMsg"><span th:text="${errorMsg}"></span></p>
</div>
But no luck, it is not working.
但没有运气，它不起作用。
回答by michal.kreuzman
It's not working because param.erroris array of strings. You must retrieve first element of array (param.error[0]) to get first value of parameter (see documentation). Besides that you can access request parameter via Web context object method #httpServletRequest.getParameterthat returns first value when parameter is multivalued (see documentation).
它不起作用，因为param.error是字符串数组。您必须检索数组 ( param.error[0]) 的第一个元素才能获得参数的第一个值（请参阅文档）。除此之外，您可以通过 Web 上下文对象方法访问请求参数#httpServletRequest.getParameter，该方法在参数为多值时返回第一个值（请参阅文档）。
Usage of Web context namespaces for request attributes
<div class="error" th:if="${param.error[0] == 'badCredentialsException'}" th:with="errorMsg=#{login.badCredentials}"> <p class="errorMsg"><span th:text="${errorMsg}"></span></p> </div>Usage of Web context object
<div class="error" th:if="${#httpServletRequest.getParameter('error') == 'badCredentialsException'}" th:with="errorMsg=#{login.badCredentials}"> <p class="errorMsg"><span th:text="${errorMsg}"></span></p> </div>
对请求属性使用 Web 上下文命名空间
<div class="error" th:if="${param.error[0] == 'badCredentialsException'}" th:with="errorMsg=#{login.badCredentials}"> <p class="errorMsg"><span th:text="${errorMsg}"></span></p> </div>Web 上下文对象的使用
<div class="error" th:if="${#httpServletRequest.getParameter('error') == 'badCredentialsException'}" th:with="errorMsg=#{login.badCredentials}"> <p class="errorMsg"><span th:text="${errorMsg}"></span></p> </div>
回答by RiZKiT
With Thymeleaf 3, I normally use #request(a short form of #httpservletrequest) and #strings.equals()for that, which will look like this:
对于 Thymeleaf 3，我通常使用#request（的缩写形式#httpservletrequest），#strings.equals()为此，它看起来像这样：
<div th:if="${#strings.equals(#request.getParameter('error'), 'badCredentialsException')}"></div>
