求用ExtJs store过滤器写一个省市县三级联动

求大牛帮忙！！！

listeners:{
'select':function(combo,records,eOpts){
storeCity.filterBy(function(record)
{
alert(Ext.getCmp("ProvinceName").value);
return record.get('code') == Ext.getCmp("ProvinceName").value;
alert(1223);
})
}
}

http://blog.csdn.net/Charles_jia/article/details/48479803

extjs combobox省市县3级联动示例