我发布的这个单选按钮表单的正确语法是什么。没有单选按钮,表单可以正常工作,只有当我添加它们时,我会收到一条错误消息,未定义变量:where_to_search
<form action="" method="POST" >
<div class="control-group">
<label class="control-label">Search By:</label>
<div class="controls">
<label class="radio">
<input type="radio" name="where_to_search" id="optionsRadios1" value="1" checked>
Group Name
</label>
<label class="radio">
<input type="radio" name="where_to_search" id="optionsRadios2" value="2">
Group Description
</label>
</div>
</div>
<input class="span2" name="keywords" id="appendedPrependedInput" size="15" placeholder="Search groups.." type="text"/><button class="btn" value="Go" type="submit">Go!</button>
</form>