ext combobox 加载完后台数据后 再赋值如何弄

function setCombo(id,allInfo)/*id为combobox的id，allInfo参数的格式为 [{value:,text:},......]*/
{
       var comBo=Ext.getCmp(id);
       if(!comBo) return false;
       var store=comBo.getStore();
       store.removeAll();
        for(var i=0;i<=allInfo.length-1;i++)
        {
             var record=new Ext.data.Record({value:allInfo[i].value,text:allInfo[i].text});
             store.add(record);
        }
        if(allInfo.nowValue)
          comBo.setValue(allInfo.nowValue);
}