extjs 4：将模型数据填充到PHP + MySql的组合框中

Ext.define('User', {
     extend: 'Ext.data.Model',
     fields: [
         {name: 'DeviceID', type: 'string'},
         {name: 'VehicleNo',  type: 'string'}
     ]
 });

    var store1 = new Ext.data.JsonStore({
    // store configs
    model: 'User',
    storeId: 'myStore',
    proxy: {
        type: 'ajax',
        url: 'combobox.php',
        id:'1', //show only the group ID is 1,this id are flexible,not necessary is 1
        fields: ['DeviceID','VehicleNo']
    } 
});
Ext.define('User', {
     extend: 'Ext.data.Mod