yii\db\baseActiveRecord

public function afterSave($insert, $changedAttributes)
    {
        $this->trigger($insert ? self::EVENT_AFTER_INSERT : self::EVENT_AFTER_UPDATE, new AfterSaveEvent([
            'changedAttributes' => $changedAttributes
        ]));
    }

调用

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            throw new StaleObjectException('The object being updated is outdated.');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;
    }

好像是在\vendor\yiisoft\yii2\db
BaseActiveRecord.php 这个文件中

好像是在\vendor\yiisoft\yii2\db
BaseActiveRecord.php 这个文件中