Yii Framework: Upload a file using a model 2

Item.php

<?php
class Item extends ActiveRecord
{
    ...
    /**
     * @see CActiveRecord::afterValidate()
     */
    protected function afterValidate()
    {
        if (!$this->hasErrors()) {
            $this->upload();
        }
        return parent::afterValidate();
    }

    /**
     * Upload file.
     */
    private function upload()
    {
        $file = CUploadedFile::getInstance($this, 'image');
        $this->image = sha1(mt_rand() . microtime()) . '.' . $file->extensionName;
        $file->saveAs($this->imagePath . $this->image);
    }
    
    /**
     * Get images path.
     * @return string images path
     */
    private function getImagePath()
    {
        return Yii::getPathOfAlias('webroot.images') . DIRECTORY_SEPARATOR;
    }
    ...