Yii DB UserIdentity

yii-db-useridentity.php

<?php

class UserIdentity extends CUserIdentity
{
    private $_id;
 
    public function authenticate()
    {
        $username = strtolower($this->username);
        $user = User::model()->find('LOWER(username) = ?', array($username));
        if ($user === null) {
            $this->errorCode = self::ERROR_USERNAME_INVALID;
        } elseif (md5($this->password) !== $user->password) {
            $this->errorCode = self::ERROR_PASSWORD_INVALID;
        } else {
            $this->_id = $user->id;
            $this->username = $user->username;
            $this->errorCode = self::ERROR_NONE;
        }
 
        return !$this->errorCode;
    }
 
    public function getId()
    {
        return $this->_id;
    }
}