RowManager.php

<?php
/**
 * RowManager.php
 *
 * LICENSE: Some license information
 *
 * @copyright  2006 New Media Center - University of Nebraska-Lincoln
 * @license    http://www.gnu.org/licenses/gpl.txt GPL
 * @version    0.0.1
 * @link       http://nmc.unl.edu/
 * @since      File available since Release 0.0.1
*/

require_once('Zend.php');
Zend::loadInterface('Nmc_SingletonInterface');

/**
 * Nmc_Db_RowManager - Keeps track of Nmc_Db_Table_Row instances
 *
 * @copyright  2006 New Media Center - University of Nebraska Lincoln
 * @license    http://www.gnu.org/gpl.txt GPL
 * @version    Release: 0.0.1
 * @link       http://nmc.unl.edu/
 * @since      Class available since Release 0.0.1
 */

class Nmc_Db_RowManager implements Nmc_SingletonInterface
{

    static protected $_instance = null;
    protected $_rows = null;

	protected function __construct()
	{
	    $this->_rows = array();
	}

	/**
	 * Return the one true instance of the class
	 *
	 * @return Nmc_Db_RowManager
	 */
	static public function getInstance()
	{
	    if(!self::$_instance) {
	        self::$_instance = new Nmc_Db_RowManager();
	    }
	    return self::$_instance;
	}

	/**
	 * getRow - returns the one true instance of the row you want
	 *
	 * @param string $rowClass
	 * @param array $config
	 * @return Nmc_Db_Table_Row
	 */
    public function getRow($rowClass, $config)
    {
        $tableInfo = $config['table']->info();

        $tableName = $tableInfo['name'];
        $primaryKeyName = $tableInfo['primary'];

        $key = $this->_generateKey($tableName, $config['data'][$primaryKeyName]);

        if(!array_key_exists($key, $this->_rows)) {
            $this->addRow(new $rowClass($config), $key);
            //echo '$this->addRow(new ' . $rowClass . '($config), ' . $key . ');' . "<br />\n";
        }

        $row = $this->_rows[$key];
        return $row;
    }

    /**
     * addRow - Add a row to the manager
     *          This should only be used after saving a NEW row.
     *
     * @param Nmc_Db_Table_Row $row - row to be added
     * @param string[optional] $key - the key for the row (internal use ONLY)
     * @return void
     * @throws Zend_Db_Exception
     */
    public function addRow(Nmc_Db_Table_Row $row, $key = null)
    {

        if(!$key) {
            $tableInfo = $row->getTable()->info();
            $tableName = $tableInfo['name'];
            if($row->getPrimaryKey() == null) {
                // row not in db, doesn't need (and can't use) management
                return;
            }
            $key = $this->_generateKey($tableName, $row->getPrimaryKey());
        }

        // echo "Generating new record for: $key\n";

        if(array_key_exists($key, $this->_rows) && $this->_rows[$key] !== $row) {
            //throw new Zend_Db_Exception('Row is already being managed, one copy is stale');
            //trigger_error('Row is already being managed, one copy may be stale.', E_USER_NOTICE);
        }
        $this->_rows[$key] = $row;

        //echo "Done: $key (" . $this->_rows[$key] . ")\n";
    }

    protected function _generateKey($tableName, $primaryKey)
    {
        return $tableName . '::' . $primaryKey;
    }
}

?>