PHP and Prototype's AJAX

我有一个php函数，它返回JSON以响应ajax请求的交付费用。这是 php 函数：

public function getDeliveryOptions($weight, $postcode)
{
    if($weight == 0)
    {
        return array(array("name" => "Non-Deliverable", "value" => "0.00"));
    }
    $this->db->where('dmc_lower_boundary <=', $weight);
    $this->db->where('dmc_upper_boundary >=', $weight);
    if(preg_match("([aA][bB](3[1-8]|4[1-5]|5[1-6])'s?[1-9][a-zA-Z]{2}|[fF][kK](19|20|21)'s?[1-9][a-zA-Z]{2}|[hH][sS][1-9]'s?[1-9][a-zA-Z]{2}|[iI][vV][1-9]{1,2}'s?[1-9][a-zA-Z]{2}|[kK][aA](27|28)'s?[1-9][a-zA-Z]{2}|[kK][wW][1-9]{1,2}?'s?[1-9][a-zA-Z]{2}|[pP][aA][2-8][0-9]'s?[1-9][a-zA-Z]{2}|[pP][hH]([156789]|1[056789]|[2-5][0-9]){1,2}'s?[1-9][a-zA-Z]{2}|[zZ][eE][1-9]'s?[1-9][a-zA-Z]{2})", $postcode))
    {
        $this->db->where("dm_id = ", 1);
        $this->db->or_where("dm_id =", 3);
    }
    elseif(preg_match("/([bB][tT][1-9]{1,2}'s?[1-9][a-zA-Z]{2}|[iI][mM][1-9]{1,2}'s?[1-9][a-zA-Z]{2}|[tT][rR](21|22|23|24|25)'s?[1-9][a-zA-Z]{2})/", $postcode))
    {
        $this->db->where("dm_id =", 1);
        $this->db->or_where("dm_id =", 4);
    }
    elseif(preg_match("/([gG][yY][1-9]'s?[1-9][a-zA-Z]{2}|[jJ][eE][1-4]'s?[1-9][a-zA-Z]{2})/", $postcode))
    {
        $this->db->where("dm_id =", 1);
        $this->db->or_where("dm_id =", 5);
    }
    else
    {
        $this->db->where("dm_id =", 1);
        $this->db->or_where("dm_id =", 2);
    }
    $this->db->group_by("dm_id");
    $query = $this->db->get("delivery_method_option_views");
    //print_r($query->result());
    //print_r(json_encode($query->result()));
    return(json_encode($query->result()));
}

这是我的javascript（使用原型）将结果发送到服务器并使用响应创建单选按钮：

function updateDelivery()
{
if($('deliveryUpdate') == null)
{
    return false;
}
// This 'observes' our form submit - sort of like onsubmit
$('deliveryUpdate').observe('submit', function(evt) {
    // Stop the actual event from happening
    evt.stop();
    // This is the url we submit to - change it as needed
    var url = '/checkout/updateDelivery';
    //This will be the form and div we update
    var containerForm = $('deliveryUpdate');
    var optionsDisplay = $('deliveryOptions');
    // Grab all the info in the form
    var form_data = containerForm.serialize();
    var form = containerForm.innerHTML;
    // Here we make the request
    new Ajax.Request(url, {
        method: 'post',
        parameters: form_data,
        onCreate: function() {
            form = containerForm.innerHTML;
            containerForm.update(form+'<img src="/images/loader.gif" alt="loading..." class="loader" />');
        },
        onSuccess: function(transport) {
            containerForm.update(form);
            NVPResponse = transport.responseText;
            if(NVPResponse !== '[object Array]')
            {
                NVPResponse = new Array(NVPResponse);
            }
            alert(NVPResponse);
            options = "";
            for(i=0; i<NVPResponse.length; ++i)
            {
                options += '<label for="delivery">'+NVPResponse[i].dm_name+'</label><input type="radio" name="delivery" value="'+NVPResponse[i].dmc_price+'" />';
            }
            //optionsDisplay.update(NVPResponse);
            optionsDisplay.update(options);
        }
    });
});
}

如果我只是使用 JSON 结果进行更新（对于邮政编码 ab31 2as），我会得到以下内容：

Calculate Delivery Costs[{"dm_id":"1","dm_name":"Royal Mail","dm_admin_name":"Royal Mail","dmc_lower_boundary":"101","dmc_upper_boundary":"250","dmc_price":"3.65"},{"dm_id":"3","dm_name":"Courier","dm_admin_name":"Fed Ex Zone 4","dmc_lower_boundary":"101","dmc_upper_boundary":"250","dmc_price":"4.50"}]

但是，如果我使用选项 var 进行更新，则标签文本和单选按钮值所在的位置会出现"未定义"。这是内置在 onSuccess 函数的 for 循环中。有什么想法吗？

编辑

我在 for 循环之前添加了以下代码，因为我尝试将 JSON 字符串用作对象而不是对象：

NVPResponse = JSON.parse(NVPResponse);