关于Extjs Combobox默认值选中的有关问题

var typeid_device_combo_store =new Ext.data.JsonStore({
                        url:'datasource/output/device_query.php',
                        root:'results',
                        id:'id',
                        totalProperty:'total',
                        fields:[
                                    {name:'id'},
                                    {name:'name'},
                                    {name:'typeid'},
                                    {name:'typecode'},
                                    {name:'typename'}
                                    
                                ],
                        remoteSort:true
                        
                    });
        
    //typeid_device_combo_store.reload({params:{start:0,limit:255}});
    typeid_device_combo_store.on('load',function(){
    Ext.getCmp('edit_cfgnode_typeid').setValue(1);
                            
    });