如何提交表格而不丢失已经在同一表格中选择的值 [英] how to submit a form without losing values already selected at the same form

问题描述

我正在使用带有下拉列表的jstl.

I am using jstl with dropdown lists.

当我单击提交"按钮时，我成功完成了规范，但是int下拉列表的值被重新初始化.

When i click submit button i success the specification but values int dropdownlists are reinitialized.

所以我要提交表单而不丢失表单中已经选择的值，因为我需要始终保持表单中的同一级别.更清楚地说，用户从ddl中选择一个值，然后单击编辑"按钮以显示其他值选项，并以相同的形式填写它们，而不会丢失他选择的内容.

So I want to submit form without loosing the values already selected in the form because I need to stay always at the same level in the form.To be more clear, user choose a value from ddl and click edit button to show other options and fill them at the same form without loosing what he has selected.

我试图那样处理...

I have tried to deal like that...

<form action="myjsp.jsp" method="post">
<input type="Submit" value="Edit">

...但是它不起作用.

...but it doesn't work.

谢谢您的帮助.

推荐答案

您需要使用请求参数值预置输入.您可以通过${param.name}访问EL中的参数值.基本上:

You need to preset the inputs with the request parameter values. You can access parameter values in EL by ${param.name}. Basically:

<input type="text" name="foo" value="${param.foo}">

请注意，这对 XSS 敏感.您始终需要清理用户输入.您可以使用 JSTL函数为此的taglib.

Note that this is XSS sensitive. You always need to sanitize the user inputs. You can use the JSTL functions taglib for this.

<input type="text" name="foo" value="${fn:escapeXml(param.foo)}">

如果通过HTML <select>元素呈现下拉菜单，则会有些棘手.您需要设置所讨论的HTML <option>元素的selected属性.只要选项值与请求参数值匹配，就可以使用EL中的三元运算符打印selected属性.

In case of dropdowns rendered by HTML <select> element, it's a bit trickier. You need to set the selected attribute of the HTML <option> element in question. You can make use of the ternary operator in EL to print the selected attribute whenever the option value matches the request parameter value.

基本示例:

<select name="foo">
   <c:forEach items="${options}" var="option">
       <option ${param.foo == option ? 'selected' : ''}>${option}</option>
   </c:forEach>
</select>

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