items: [{
    xtype: "combo",
    name: "site_id",
    triggerAction: 'all',
    lazyRender: false,
    selectOnFocus: true,
    forceSelection: true,
    editable: false,
    allowBlank: false,
    mode: 'local',
    fieldLabel: '请选择',
    width: 180,
    store:new Ext.data.Store({   
        proxy: new Ext.data.HttpProxy({
            url: '/mis/expert?method=site_list'
        }),   
        reader: new Ext.data.JsonReader({
            root: 'site_info'
        },[
            { name: 'site_id', mapping: 'site_id' },
            { name: 'site_url', mapping: 'site_url'}
        ])
    }),
    valueField: 'sie_id',
    displayField: 'site_url'
}]