ExtJS ComboBox下拉框

下拉框，选项数据从服务器端获取         new Ext.form.ComoBox({             id:'',              hiddenName:'', //后台的变量名             fieldLabel:'',       allowBlank:false,             emptyText:'请选择',             displayField:'name', //显示列             valueField:'id', //值            mode: 'local' ,             editable: false,             triggerAction: 'all',             anchor:'85%',             store:new Ext.data.Store({              autoLoad:true, //自动加载数据              proxy: new Ext.data.HttpProxy({url: 'demo.action'}),         reader: new Ext.data.JsonReader({              root: 'goodstypeList'              }, [{name : 'name'},{name : 'id'}]              )            })         });