Yii2 TimestampBehavior行为

<?php
/**
 * @link http://www.yiiframework.com/
 * @copyright Copyright (c) 2008 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

namespace yiiehaviors;

use yiiaseInvalidCallException;
use yiidbBaseActiveRecord;

/**
 * TimestampBehavior automatically fills the specified attributes with the current timestamp.
 *
 * To use TimestampBehavior, insert the following code to your ActiveRecord class:
 *
 * ```php
 * use yiiehaviorsTimestampBehavior;
 *
 * public function behaviors()
 * {
 *     return [
 *         TimestampBehavior::className(),
 *     ];
 * }
 * ```
 *
 * By default, TimestampBehavior will fill the `created_at` and `updated_at` attributes with the current timestamp
 * when the associated AR object is being inserted; it will fill the `updated_at` attribute
 * with the timestamp when the AR object is being updated. The timestamp value is obtained by `time()`.
 *
 * Because attribute values will be set automatically, it's a good idea to make sure `created_at` and `updated_at` aren't
 * in `rules()` method of the model.
 *
 * For the above implementation to work with MySQL database, please declare the columns(`created_at`, `updated_at`) as int(11) for being UNIX timestamp.
 *
 * If your attribute names are different or you want to use a different way of calculating the timestamp,
 * you may configure the [[createdAtAttribute]], [[updatedAtAttribute]] and [[value]] properties like the following:
 *
 * ```php
 * use yiidbExpression;
 *
 * public function behaviors()
 * {
 *     return [
 *         [
 *             'class' => TimestampBehavior::className(),
 *             'createdAtAttribute' => 'create_time',
 *             'updatedAtAttribute' => 'update_time',
 *             'value' => new Expression('NOW()'),
 *         ],
 *     ];
 * }
 * ```
 *
 * In case you use an [[yiidbExpression]] object as in the example above, the attribute will not hold the timestamp value, but
 * the Expression object itself after the record has been saved. If you need the value from DB afterwards you should call
 * the [[yiidbActiveRecord::refresh()|refresh()]] method of the record.
 *
 * TimestampBehavior also provides a method named [[touch()]] that allows you to assign the current
 * timestamp to the specified attribute(s) and save them to the database. For example,
 *
 * ```php
 * $model->touch('creation_time');
 * ```
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @author Alexander Kochetov <creocoder@gmail.com>
 * @since 2.0
 */
class TimestampBehavior extends AttributeBehavior
{
    /**
     * @var string the attribute that will receive timestamp value
     * Set this property to false if you do not want to record the creation time.
     */
    public $createdAtAttribute = 'created_at';
    /**
     * @var string the attribute that will receive timestamp value.
     * Set this property to false if you do not want to record the update time.
     */
    public $updatedAtAttribute = 'updated_at';
    /**
     * @inheritdoc
     *
     * In case, when the value is `null`, the result of the PHP function [time()](http://php.net/manual/en/function.time.php)
     * will be used as value.
     */
    public $value;


    /**
     * @inheritdoc
     */
    public function init()
    {
        parent::init();

        if (empty($this->attributes)) {
            $this->attributes = [
                BaseActiveRecord::EVENT_BEFORE_INSERT => [$this->createdAtAttribute, $this->updatedAtAttribute],
                BaseActiveRecord::EVENT_BEFORE_UPDATE => $this->updatedAtAttribute,
            ];
        }
    }

    /**
     * @inheritdoc
     *
     * In case, when the [[value]] is `null`, the result of the PHP function [time()](http://php.net/manual/en/function.time.php)
     * will be used as value.
     */
    protected function getValue($event)
    {
        if ($this->value === null) {
            returntime(); 
        }
        return parent::getValue($event);
    }

    /**
     * Updates a timestamp attribute to the current timestamp.
     *
     * ```php
     * $model->touch('lastVisit');
     * ```
     * @param string $attribute the name of the attribute to update.
     * @throws InvalidCallException if owner is a new record (since version 2.0.6).
     */
    public function touch($attribute)
    {
        /* @var $owner BaseActiveRecord */
        $owner = $this->owner;
        if ($owner->getIsNewRecord()) {
            throw new InvalidCallException('Updating the timestamp is not possible on a new record.');
        }
        $owner->updateAttributes(array_fill_keys((array) $attribute, $this->getValue(null)));
    }
}

TimestampBehavior 里面的public function init(){}初始化绑定事件处理的方法数据

/**
     * @inheritdoc
     */
    public function init()
    {
        parent::init();

        if (empty($this->attributes)) {
            $this->attributes = [
                BaseActiveRecord::EVENT_BEFORE_INSERT => [$this->createdAtAttribute, $this->updatedAtAttribute],
                BaseActiveRecord::EVENT_BEFORE_UPDATE => $this->updatedAtAttribute,
            ];
        }
    }

TimestampBehavior 父级AttributeBehavior 里面events()方法  为事件绑定执行handle :evaluateAttributes方法

/**
     * @inheritdoc
     */
    public function events()
    {
        return array_fill_keys(
            array_keys($this->attributes),
            'evaluateAttributes'
        );
    }

事件绑定的方法：evaluateAttributes方法，

 /**
     * Evaluates the attribute value and assigns it to the current attributes.
     * @param Event $event
     */
    public function evaluateAttributes($event)
    {
        if ($this->skipUpdateOnClean
            && $event->name == ActiveRecord::EVENT_BEFORE_UPDATE
            && empty($this->owner->dirtyAttributes)
        ) {
            return;
        }

        if (!empty($this->attributes[$event->name])) {
            $attributes = (array) $this->attributes[$event->name];
            $value = $this->getValue($event);
            foreach ($attributes as $attribute) {
                // ignore attribute names which are not string (e.g. when set by TimestampBehavior::updatedAtAttribute)
                if (is_string($attribute)) {
                    $this->owner->$attribute = $value;
                }
            }
        }
    }

当update 或者insert  save数据时候，BaseActiveRecord.php 里面的save()：

/**
     * Saves the current record.
     *
     * This method will call [[insert()]] when [[isNewRecord]] is true, or [[update()]]
     * when [[isNewRecord]] is false.
     *
     * For example, to save a customer record:
     *
     * ```php
     * $customer = new Customer; // or $customer = Customer::findOne($id);
     * $customer->name = $name;
     * $customer->email = $email;
     * $customer->save();
     * ```
     *
     * @param boolean $runValidation whether to perform validation (calling [[validate()]])
     * before saving the record. Defaults to `true`. If the validation fails, the record
     * will not be saved to the database and this method will return `false`.
     * @param array $attributeNames list of attribute names that need to be saved. Defaults to null,
     * meaning all attributes that are loaded from DB will be saved.
     * @return boolean whether the saving succeeded (i.e. no validation errors occurred).
     */
    public function save($runValidation = true, $attributeNames = null)
    {
        if ($this->getIsNewRecord()) {
            return $this->insert($runValidation, $attributeNames);
        } else {
            return $this->update($runValidation, $attributeNames) !== false;
        }
    }

调用ActiveRecord.php 里面的insert()  和update  ():

 public function insert($runValidation = true, $attributes = null)
    {
        if ($runValidation && !$this->validate($attributes)) {
            Yii::info('Model not inserted due to validation error.', __METHOD__);
            return false;
        }

        if (!$this->isTransactional(self::OP_INSERT)) {
            return $this->insertInternal($attributes);
        }

        $transaction = static::getDb()->beginTransaction();
        try {
            $result = $this->insertInternal($attributes);
            if ($result === false) {
                $transaction->rollBack();
            } else {
                $transaction->commit();
            }
            return $result;
        } catch (Exception $e) {
            $transaction->rollBack();
            throw $e;
        }
    }
public function update($runValidation = true, $attributeNames = null)
    {
        if ($runValidation && !$this->validate($attributeNames)) {
            Yii::info('Model not updated due to validation error.', __METHOD__);
            return false;
        }

        if (!$this->isTransactional(self::OP_UPDATE)) {
            return $this->updateInternal($attributeNames);
        }

        $transaction = static::getDb()->beginTransaction();
        try {
            $result = $this->updateInternal($attributeNames);
            if ($result === false) {
                $transaction->rollBack();
            } else {
                $transaction->commit();
            }
            return $result;
        } catch (Exception $e) {
            $transaction->rollBack();
            throw $e;
        }
    }

调用ActiveRecord.php 里面insertInternal() 和updateInternal()：

/**
     * Inserts an ActiveRecord into DB without considering transaction.
     * @param array $attributes list of attributes that need to be saved. Defaults to null,
     * meaning all attributes that are loaded from DB will be saved.
     * @return boolean whether the record is inserted successfully.
     */
    protected function insertInternal($attributes = null)
    {
        if (!$this->beforeSave(true)) {
            return false;
        }
        $values = $this->getDirtyAttributes($attributes);
        if (($primaryKeys = static::getDb()->schema->insert(static::tableName(), $values)) === false) {
            return false;
        }
        foreach ($primaryKeys as $name => $value) {
            $id = static::getTableSchema()->columns[$name]->phpTypecast($value);
            $this->setAttribute($name, $id);
            $values[$name] = $id;
        }

        $changedAttributes = array_fill_keys(array_keys($values), null);
        $this->setOldAttributes($values);
        $this->afterSave(true, $changedAttributes);

        return true;
    }
 /**
     * @see update()
     * @param array $attributes attributes to update
     * @return integer number of rows updated
     * @throws StaleObjectException
     */
    protected function updateInternal($attributes = null)
    {
        if (!$this->beforeSave(false)) {
            return false;
        }
        $values = $this->getDirtyAttributes($attributes);
        if (empty($values)) {
            $this->afterSave(false, $values);
            return 0;
        }
        $condition = $this->getOldPrimaryKey(true);
        $lock = $this->optimisticLock();
        if ($lock !== null) {
            $values[$lock] = $this->$lock + 1;
            $condition[$lock] = $this->$lock;
        }
        // We do not check the return value of updateAll() because it's possible
        // that the UPDATE statement doesn't change anything and thus returns 0.
        $rows = static::updateAll($values, $condition);

        if ($lock !== null && !$rows) {
            throw new StaleObjectException('The object being updated is outdated.');
        }

        if (isset($values[$lock])) {
            $this->$lock = $values[$lock];
        }

        $changedAttributes = [];
        foreach ($values as $name => $value) {
            $changedAttributes[$name] = isset($this->_oldAttributes[$name]) ? $this->_oldAttributes[$name] : null;
            $this->_oldAttributes[$name] = $value;
        }
        $this->afterSave(false, $changedAttributes);

        return $rows;
    }

调用BaseActiveRecord.php 里面的beforeSave(),触发$this->trigger($insert ? self::EVENT_BEFORE_INSERT : self::EVENT_BEFORE_UPDATE, $event)事件执行添加之前绑定的事件方法evaluateAttributes自动相关添加属性值:

 public function beforeSave($insert)
    {
        $event = new ModelEvent;
        $this->trigger($insert ? self::EVENT_BEFORE_INSERT : self::EVENT_BEFORE_UPDATE, $event);

        return $event->isValid;
    }

}