如何在Ext JS中为submit事件获取颗粒字段的验证？

Ext.create('Ext.form.Panel', {
    title: 'My Form',
    items: [{
        xtype: 'textfield',
        fieldLabel: 'Name',
        name: 'name',
        allowBlank: false
    }, {
        xtype: 'textfield',
        fieldLabel: 'Email',
        name: 'email',
        vtype: 'email'
    }],
    buttons: [{
        text: 'Submit',
        handler: function() {
            var form = this.up('form').getForm();
            if (form.isValid()) {
                // 表单字段验证通过，可以进行提交操作
                form.submit({
                    url: 'submit.php',
                    success: function(form, action) {
                        Ext.Msg.alert('Success', action.result.msg);
                    },
                    failure: function(form, action) {
                        Ext.Msg.alert('Failed', action.result.msg);
                    }
                });
            }
        }
    }],
    renderTo: Ext.getBody()
});