extjs留言回复功能

Ext.define('Message', {
    extend: 'Ext.data.Model',
    fields: [
        { name: 'id', type: 'int' },
        { name: 'content', type: 'string' },
        { name: 'parentId', type: 'int', defaultValue: null }
    ]
});

var messageStore = Ext.create('Ext.data.Store', {
    model: 'Message',
    proxy: {
        type: 'ajax',
        url: '/api/messages',
        reader: {
            type: 'json',
            rootProperty: 'data'
        }
    },
    autoLoad: true
});

Ext.create('Ext.grid.Panel', {
    title: '留言列表',
    store: messageStore,
    columns: [
        { text: '内容', dataIndex: 'content' },
        { text: '回复数', dataIndex: 'replyCount', renderer: function(value, metaData, record) {
            return record.replies().getCount();
        }}
    ],
    renderTo: Ext.getBody()
});

var replyForm = Ext.create('Ext.form.Panel', {
    title: '回复留言',
    items: [
        { xtype: 'textfield', name: 'content', fieldLabel: '内容' },
        { xtype: 'hiddenfield', name: 'parentId' }
    ],
    buttons: [
        {
            text: '提交',
            handler: function() {
                var form = this.up('form').getForm();
                if (form.isValid()) {
                    form.submit({
                        url: '/api/replies',
                        success: function(form, action) {
                            Ext.Msg.alert('成功', '回复已提交！');
                            replyForm.getForm().reset();
                        },
                        failure: function(form, action) {
                            Ext.Msg.alert('失败', action.result.message);
                        }
                    });
                }
            }
        }
    ],
    renderTo: Ext.getBody()
});