Yii2 Active Record 的生命周期
当你实现各种功能的时候，会发现了解 Active Record 的生命周期很重要。 在每个生命周期中，一系列的方法将被调用执行，您可以重写这些方法 以定制你要的生命周期。您还可以响应触发某些 Active Record 事件 以便在生命周期中注入您的自定义代码。这些事件在开发 Active Record 的 行为时特别有用， 通过行为可以定制 Active Record 生命周期的 。
Active Record 的生命周期 大致划分为以下几种：
- 实例化生命周期（New Instance Life Cycle）
- 查询数据生命周期（Querying Data Life Cycle）
- 保存数据生命周期（Saving Data Life Cycle）
- 删除数据生命周期（Deleting Data Life Cycle） <
- 刷新数据生命周期（Refreshing Data Life Cycle）
以上内容来自 Yii2.0权威指南 ，更多介绍请参考 Active Record 的生命周期
以下为 Acative Record 的各种事件
代码语言：javascript复制/**
* @event Event an event that is triggered when the record is initialized via [[init()]].
*/
const EVENT_INIT = 'init';
/**
* @event Event an event that is triggered after the record is created and populated with query result.
*/
const EVENT_AFTER_FIND = 'afterFind';
/**
* @event ModelEvent an event that is triggered before inserting a record.
* You may set [[ModelEvent::isValid]] to be `false` to stop the insertion.
*/
const EVENT_BEFORE_INSERT = 'beforeInsert';
/**
* @event AfterSaveEvent an event that is triggered after a record is inserted.
*/
const EVENT_AFTER_INSERT = 'afterInsert';
/**
* @event ModelEvent an event that is triggered before updating a record.
* You may set [[ModelEvent::isValid]] to be `false` to stop the update.
*/
const EVENT_BEFORE_UPDATE = 'beforeUpdate';
/**
* @event AfterSaveEvent an event that is triggered after a record is updated.
*/
const EVENT_AFTER_UPDATE = 'afterUpdate';
/**
* @event ModelEvent an event that is triggered before deleting a record.
* You may set [[ModelEvent::isValid]] to be `false` to stop the deletion.
*/
const EVENT_BEFORE_DELETE = 'beforeDelete';
/**
* @event Event an event that is triggered after a record is deleted.
*/
const EVENT_AFTER_DELETE = 'afterDelete';
/**
* @event Event an event that is triggered after a record is refreshed.
* @since 2.0.8
*/
const EVENT_AFTER_REFRESH = 'afterRefresh';
