example how not to use Active Record pattern

1.php

<?php
/**
 * user model
 *
 * @package User
 * @author aur1mas <aur1mas@devnet.lt>
 */
class Model_User extends Base_User
{
    
    /**
     * returns user primary key
     *
     * @return int
     * @author aur1mas <aur1mas@devnet.lt>
     */
    public function getId()
    {
        return $this->_id;
    }
    
    /**
     * finds user by its username
     *
     * @param string $username 
     * @return Model_User
     * @author aur1mas <aur1mas@devnet.lt>
     */
    public function findByUsername($username)
    {
        return Doctrine::getTable("Model_User")->findOneByUsername((string)$username);
    }
    
    /**
     * returns user screen name
     *
     * @return string
     * @author aur1mas <aur1mas@devnet.lt>
     */
    public function getScreeName()
    {
        return $this->_first_name . " " . $this->_last_name;
    }
    
    /**
     * user authentication
     * 
     * @param string $username
     * @param string $password
     * @throws Exception
     * @return Model_User
     */
    public static function authenticate($username, $password)
    {        
        $user = Doctrine::getTable('Model_User')->findOneByEmail($username);
        if ($user instanceof Model_User && $user->password === sha1($password . $this->_salt)) {
            return $user;
        }

        throw new Zend_Controller_Action_Exception("Wrong credentials");
    }
}

2.1.php

<?php
/**
 * view helper which creates user screename
 *
 * @package App_View
 * @author aur1mas <aur1mas@devnet.lt>
 */
class App_View_Helper_ScreeName extends Zend_View_Helper_Abstract
{
    
    /**
     * returns user screen name
     *
     * @param Model_User $user 
     * @return string
     * @author aur1mas <aur1mas@devnet.lt>
     */
    public function screeName(Model_User $user)
    {
        return $user->first_name . " " . $user->last_name;
    }
}

2.2.php

<?php
/**
 * service to work with user data
 *
 * @package User
 * @author aur1mas <aur1mas@devnet.lt>
 */
class Service_User
{
    /**
     * finds user by its username
     *
     * @param string $username 
     * @return Model_User
     * @author aur1mas <aur1mas@devnet.lt>
     */
    public function findByUsername($username)
    {
        return Doctrine::getTable("Model_User")->findOneByUsername((string)$username);
    }
    
    /**
     * user authentication
     * 
     * @param string $username
     * @param string $password
     * @throws Zend_Controller_Action_Exception
     * @return Model_User
     */
    public static function authenticate($username, $password)
    {        
        $user = Doctrine::getTable('Model_User')->findOneByEmail($username);
        if ($user instanceof Model_User && $user->password === sha1($password . $this->_salt)) {
            return $user;
        }

        throw new Zend_Controller_Action_Exception("Wrong credentials");
    }
}

2.3.php

<?php
/**
 * user model
 *
 * @package User
 * @author aur1mas <aur1mas@devnet.lt>
 */
class Model_User extends Base_User
{
    
    /**
     * returns user primary key
     *
     * @return int
     * @author aur1mas <aur1mas@devnet.lt>
     */
    public function getId()
    {
        return $this->_id;
    }
}