AMAZIUM: IT and Management Consulting

(NOTE: from ZF 1.10 onwards a MultiDb resource is available in the library: Zend_Application_Resource_Multidb)

It worked fine, but with the new classes looming on the horizon, I decided to try it out.

I managed to setup an application quite quickly. Although I encountered a few bugs, there were no major blocking issues. As a DBA, I often use different databases from a single application. So I need to be able to initiate them in a simple and easy way.

With the Zend_Application, came code for a database resource as well. You basically put your database config in your ini file and bootstrap the database resource. It works like a charm, until you need multiple databases. You can go ahead and extend the database resource for every database you own, but that just doesn't cut it for me. I want a system where I put different databases in my config, and the resource handler takes care of it.

So, I decided to write my first application resource to take care of this. I played around a bit with names and had Multidb at first, but settled for dbs in the end (short for databases).

I had to add following lines to my config file:

# Add my class namespace for the autoloader

autoloadernamespaces.amz = "Amz_"

# Add my resource path to the plugin path
pluginpaths.Amz_Application_Resource = "Amz/Application/Resource"

# DB 1
resources.dbs.db1.adapter = PDO_MYSQL
resources.dbs.db1.params.dbname = db1
resources.dbs.db1.params.username = user1
resources.dbs.db1.params.password = ******
resources.dbs.db1.params.hostname = localhost
resources.dbs.db1.isDefaultTableAdapter = false

# DB 2
resources.dbs.db2.adapter = PDO_MYSQL
resources.dbs.db2.params.dbname = db2
resources.dbs.db2.params.username = user2
resources.dbs.db2.params.password = ******
resources.dbs.db2.params.hostname = localhost
resources.dbs.db2.isDefaultTableAdapter = false

My new resource class looks like this:

<?php
/**
 * Amazium Library
 *
 * @category   Amz
 * @package    Amz_Application
 * @subpackage Resource
 * @copyright  Copyright (c) 2009 Amazium (http://www.amazium.be)
 */

/**
 * Resource for creating multiple database adapters
 *
 * @uses       Zend_Application_Resource_Base
 * @category   Amz
 * @package    Amz_Application
 * @subpackage Resource
 * @copyright  Copyright (c) 2009 Amazium (http://www.amazium.be)
 */
class Amz_Application_Resource_Dbs extends Zend_Application_Resource_ResourceAbstract
{
    
    /**
     * Adapter to use
     *
     * @var array
     */
    protected $_db = array();
    
    /**
     * Default adapter
     *
     * @var boolean
     */
    protected $_defaultDb = null;

    /**
     * Adapter type to use
     * 
     * @return string
     */
    public function getAdapter($db)
    {
        $db = $this->isValidDb($db);
        if (isset($this->_options[$db]['adapter'])) {
            return $this->_options[$db]['adapter'];
        }
        return null; 
    }

    /**
     * Adapter parameters
     * 
     * @return array
     */
    public function getParams($db)
    {
        $db = $this->isValidDb($db);
        if (isset($this->_options[$db]['params'])) {
            return $this->_options[$db]['params'];
        }
        return array();
    }

    /**
     * Is this adapter the default table adapter?
     * 
     * @return void
     */
    public function isDefaultTableAdapter($db)
    {
        $db = $this->isValidDb($db);
        if (isset($this->_options[$db]['isDefaultTableAdapter'])) {
            return $this->_options[$db]['isDefaultTableAdapter'];
        }
        return false;
    }

    /**
     * Retrieve initialized DB connection
     * 
     * @return null|Zend_Db_Adapter_Interface
     */
    public function getDbAdapter($db = null)
    {
        // check if the DB is valid
        $db = $this->isValidDb($db, true);
        if (is_null($db) && is_null($db = $this->_defaultDb)) {
            return null;
        }
        
        if ((!isset($this->_db[$db]) || (null === $this->_db[$db])) 
            && (null !== ($adapter = $this->getAdapter($db)))
        ) {
            $this->_db[$db] = Zend_Db::factory($adapter, $this->getParams($db));
        }
        return $this->_db[$db];
    }
    
    /**
     * Defined by Zend_Application_Resource_IResource
     *
     * @return void
     */
    public function init()
    {
        if (is_null($this->_defaultDb)) {
            $options = $this->getOptions();
            $defaultDb = null;
            foreach ($options as $db=>$dbOptions) {
                if (null !== ($adapter = $this->getDbAdapter($db))) {
                    if ($this->isDefaultTableAdapter($db) || is_null($defaultDb)) {
                        $defaultDb = $db;
                    }
                }
            }
            if (!is_null($defaultDb)) {
                $this->_defaultDb = $defaultDb;
                Zend_Db_Table::setDefaultAdapter($this->getDbAdapter($defaultDb));
            }
        }
    }
    
    /**
     * Check if a database key is valid
     *
     * @param string $db
     * @param boolean $revertToDefaultDb
     * @return string
     */
    public function isValidDb($db, $revertToDefaultDb = false)
    {
        $db = strtolower(trim($db));
        if (!in_array($db, array_keys($this->_options))) {
            if (!$revertToDefaultDb) {
                $db = $this->_defaultDb;
            } else {
                throw new Zend_Application_Resource_Exception('Invalid database specified');
            }
        }
        return $db;
    }

}

And last but not least, here's my Bootstrap file for loading and using the database:

class Bootstrap extends Zend_Application_Bootstrap_Base
{

    public function run()
    {
        $this->bootstrap('dbs');
        $dbs = $this->getPluginResource('dbs');
        Zend_Registry::set('db1', $dbs->getDbAdapter('db1'));
        Zend_Registry::set('db2', $dbs->getDbAdapter('db2'));
        
        $this->bootstrap('frontController');
        
        $this->frontController->dispatch();
    }
}

Enjoy!