jqGrid 如何获取格式前的数据：报错

我用jqGrid画了一个表格，里面有一列的数据被我格式了。现在我想在选择表格中某一行的时候读取被格式那一列的为格式之前的数据，要怎么写呢？

我的代码：

var mystr="<?xml version='1.0' encoding='UTF-8'?><Service><Result><DTO><ProductList><entry><productCode>CODE1</productCode><productName>Name 1</productName></entry><entry><productCode>CODE2</productCode><productName>Name 2</productName></entry></ProductList></DTO></Result></Service>";

jQuery().ready(function (){
                jQuery("#list1").jqGrid({
                 datatype: 'xmlstring',
                    datastr: mystr,
                    colNames:['Product Code', 'Product Name'],
                    colModel:[
                     {name:'id',index:'id', width:75, formatter:formateProduct, frozen :true,xmlmap:"productCode" },
                     {name:'invdate',index:'invdate', width:90, xmlmap:"productName"},
                    ],
             xmlReader: {
             root:"Service>Result>DTO>ProductList",
             row:"entry",
             repeatitems:false,
             id : "asin"},
                    Height: 800,
                    width:  1000,
                    autowidth: true,
                    //rowList:[10,20,30],
                    pager: jQuery('#pager1'),
                    sortname : 'id',
                    viewrecords : 'true',
                    sortorder: 'desc',
                    caption  : "XML Example",
                    onSelectRow: function(rowid) {

                     },
                    loadonce:true,
           scroll:1,
           rowNum:20
           //gridview:true
                });
                jQuery("#list1").jqGrid('navGrid','#pager1',{edit:false,add:false,del:false});
            });
            function formateProduct( cellvalue, options, rowObject )
            {
           return "Test" ;           }