如果用户没有价值，则在JSP中显示代码-< c:choose>不工作

问题描述

如果用户在系统中没有任何设置，我试图向我的Spring JSP中添加一些代码以显示自治市镇列表.

I am trying to add some code to my Spring JSP to display a list of boroughs if the user does not have one setup in the system.

这是我的JSP代码:

<form:hidden path="borough" />
            <c:choose>
                <c:when test="${empty borough}">
                            <tr>
                            <td width="129"><span class="ast">*</span>Borough: </td>
                            <td width="361">
                                    <form:select path="borough">
                                          <form:option value="Staten Island">Staten Island</form:option>
                                          <form:option value="Queens">Queens</form:option>
                                          <form:option value="Brooklyn">Brooklyn</form:option>
                                          <form:option value="Bronx">Bronx</form:option>
                                          <form:option value="Manhattan">Manhattan</form:option>
                                    </form:select>              
                            </td>
                        </tr>
                </c:when>
                <c:otherwise>
                        <form:hidden path="borough" />
                </c:otherwise>
            </c:choose>

c:choose之前的隐藏字段仅用于调试.这是我的输出:

The hidden field before the c:choose is for debugging only. Here is my output:

<input id="borough" name="borough" type="hidden" value="Queens"/>



                            <tr>
                            <td width="129"><span class="ast">*</span>Borough: </td>
                            <td width="361">
                                    <select id="borough" name="borough">
                                          <option value="Staten Island">Staten Island</option>
                                          <option value="Queens" selected="selected">Queens</option>
                                          <option value="Brooklyn">Brooklyn</option>

                                          <option value="Bronx">Bronx</option>
                                          <option value="Manhattan">Manhattan</option>
                                    </select>               
                            </td>
                        </tr>

因此，它似乎认为自治市镇总是很熟练?

So it looks like it thinks borough is always emply?

推荐答案

您的<form:form>中的"commandName"属性是什么?您将需要引用borough作为命令对象的属性.例如:

What is the "commandName" attribute in your <form:form>? You will need to reference borough as a property of your command object. For example:

<c:when test="${empty command.borough}">

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