So why would you want to apply filters to your result set? Usually my domain models don’t inherit from Zend_Db_Table_Row but that is the data type I get from the Paginator when I use the DbTableSelect adapter (wrapped in a nice Zend_Db_Table_Rowset). Instead, I would like to load my rows into my models and preferably without using the Paginator abilities or having to apply weird hacks. Previously this was only possible (in a sane way) by subclassing an adapter so it could return a collection of model objects instead of a rowset. With the new filter support you can just inject a filter to do this for you.

Lets have a look at an example. In this example I want to list all my users from the database. I’ll grab the name of the user from the row and inject it into a User object.

<?php
class User
{
    private $_name = '';

    public function getName()
    {
        return $this->_name;
    }

    public function setName($name)
    {
        $this->_name = $name;
    }
}

class UserFilter implements Zend_Filter_Interface
{
    public function filter($rows)
    {
        $users = array();

        foreach ($rows as $row) {
            $user = new User();
            $user->setName($row->name);

            $users[] = $user;
        }

        return $rows;
    }
}

class MyModel
{
    public static function getUserPaginator()
    {
        $userTable = new UserTable();
        $paginator = Zend_Paginator::factory($userTable->select());
        $paginator->setFilter(new UserFilter());

        return $paginator;
    }
}

$paginator = MyModel::getUserPaginator();
$items = $paginator->getCurrentItems();

foreach ($items as $user) {
    echo 'Current name: ' . $user->getName() . '<br />' . PHP_EOL;
}

To simplify adding a simple filter to your paginator I’ve also added Zend_Filter_Callback. This allows you to specify a callback method that does the same as the filter in the previous example.

<?php
class MyModel
{
    public static function getUserPaginator()
    {
        $userTable = new UserTable();
        $paginator = Zend_Paginator::factory($userTable->select());
        $paginator->setFilter(new Zend_Filter_Callback(
            array('MyModel', 'filter'))
        );

        return $paginator;
    }

    public static function filter($rows)
    {
        $users = array();

        foreach ($rows as $row) {
            $user = new User();
            $user->setName($row->name);

            $users[] = $user;
        }

        return $rows;
    }
}

The callback also accepts object instead of a static reference to a class. Internally it uses call_user_func to execute the filter() method, so any notation that works there, works with the Callback filter.

Enjoy!

<?php
/**
 * BSD LICENSE
 *
 * Copyright (c) 2009, norm2782
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of norm2782 nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY norm2782 ''AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL norm2782 BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * Set production mode.
 * If set to false, exceptions will bubble through to the Flex frontend
 *
 * @var bool
 */
$production = false;

/**
 * Determine the absolute path of the AMF server
 *
 * @var string
 */
define('ABSPATH', dirname(__FILE__) . '/');

/**
 * One directory below docroot. Your config file and library dir should be here.
 *
 * @var string
 */
define('SUBPATH', dirname(ABSPATH));

/**
 * You should make sure Zend Framework is in your include path
 */
set_include_path(
    implode(PATH_SEPARATOR, array(
        SUBPATH . '/library',
        get_include_path()
    ))
);

/**
 * Include the WordPress config file
 */
$configFile = SUBPATH . '/wp-config.php';

if (!file_exists($configFile)) {
    throw new Exception('WordPress config file was not found!');
}

require_once $configFile;

/**
 * No need to config more stuff from this point on
 */

/**
 * @see Zend_Amf_Server
 */
require_once 'Zend/Amf/Server.php';

/**
 * @see Zend_Db_Adapter_Pdo_Mysql
 */
require_once 'Zend/Db/Adapter/Pdo/Mysql.php';

/**
 * @see Zend_Paginator
 */
require_once 'Zend/Paginator.php';

/**
 * @see Zend_Paginator_Adapter_DbSelect
 */
require_once 'Zend/Paginator/Adapter/DbSelect.php';

/**
 * Simple class to expose wordpress data through AMF
 *
 * @author norm2782
 */
class Wp_Amf_Gateway
{
    /**
     * Database adapter
     *
     * @var Zend_Db_Adapter_Pdo_Mysql
     */
    private $_db = null;

    /**
     * WordPress table prefix
     *
     * @var string
     */
    private $_prefix = null;

    /**
     * Constructor
     *
     * @param array $dbConfig
     * @param string $prefix
     * @return void
     */
    public function __construct(array $dbConfig, $prefix)
    {
        $this->_db = new Zend_Db_Adapter_Pdo_Mysql($dbConfig);
        $this->_db->query('SET NAMES `utf8`');

        $this->_prefix = $prefix;
    }

    /**
     * Get paginated results for the provided query
     *
     * @param Zend_Db_Select $select
     * @param int $page
     * @param int $itemsPerPage
     * @return array
     */
    private function _getPaginated(Zend_Db_Select $select, $page, $itemsPerPage)
    {
        $paginator = new Zend_Paginator(
            new Zend_Paginator_Adapter_DbSelect($select)
        );

        $paginator->setCurrentPageNumber($page)
                  ->setItemCountPerPage($itemsPerPage);

        return array(
            'info'  => $paginator->getPages(),
            'items' => $paginator->getCurrentItems()
        );
    }

    /**
     * Get the comments for the specified post ID
     *
     * @param int $postId
     * @param int $page
     * @param int $itemsPerPage
     * @return array
     */
    public function getCommentsForPost($postId, $page = 1, $itemsPerPage = 10)
    {
        $select = $this->_db->select()->from($this->_prefix . 'comments')
                                      ->where('comment_post_ID = ?', $postId);

        return $this->_getPaginated($select, $page, $itemsPerPage);
    }

    /**
     * Get the meta data for the specified post ID
     *
     * @param $postId
     * @return unknown_type
     */
    public function getMetaForPost($postId)
    {
        $select = $this->_db->select()->from($this->_prefix . 'postmeta')
                                      ->where('post_id = ?', $postId);

        return $this->_db->fetchAll($select);
    }

    /**
     * Get a post by specifying its ID
     *
     * @param int $postId
     * @return array
     */
    public function getPost($postId)
    {
        $select = $this->_db->select()->from($this->_prefix . 'posts')
                                      ->where('ID = ?', $postId);

        return $this->_db->fetchOne($select);
    }

    /**
     * Get posts per page
     *
     * @param int $page
     * @param int $itemsPerPage
     * @return array
     */
    public function getPosts($page = 1, $itemsPerPage = 10)
    {
        $select = $this->_db->select()->from($this->_prefix . 'posts');

        return $this->_getPaginated($select, $page, $itemsPerPage);
    }
}

/**
 * Pass the values from wp-config.php to the Wp_Amf_Gateway class.
 */
$gateway = new Wp_Amf_Gateway(
    array(
        'host'     => DB_HOST,
        'username' => DB_USER,
        'password' => DB_PASSWORD,
        'dbname'   => DB_NAME
    ),
    $table_prefix
);

$server = new Zend_Amf_Server();
$server->setProduction($production)
       ->setClass($gateway)
       ->handle();