SpringMVC: spring form 里 inputform 必须要有一个 modelattribute 吗？

一般来说 spring form 如下用：

<form:form id="inputForm" modelAttribute="product" action="${ctx}/product/add" method="POST"\>

<form:input path="name" id="name"/>

需要后端传一个 product bean，而提交的也是 product.name

现在我想要的页面 randominput.jsp 诸如

<form:form id="inputForm" action="${ctx}/randomthings/add" method="POST"\>
<form:input path="type" type="hidden" id="type"/>
<form:input path="applePrice" id="applePrice"/>

<form:input path="location" id="location"/>

location 和 applePrice 并不在同一个 bean 内

后台大致是

 @RequestMapping(value = {"addVouchers"}, method = RequestMethod.GET)
 public String addVouchers(Model model) {
    String type = getType();
    model.addAttribute("type",type);
    return "modules/randominput";
}

这样做结果却是 java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'command' available as request attribute

如何解决啊？