/libraries/joomla/table/table.php

<?php
/**
 * @package     Joomla.Platform
 * @subpackage  Table
 *
 * @copyright   Copyright (C) 2005 - 2013 Open Source Matters, Inc. All rights reserved.
 * @license     GNU General Public License version 2 or later; see LICENSE
 */

defined('JPATH_PLATFORM') or die;

jimport('joomla.filesystem.path');

/**
 * Abstract Table class
 *
 * Parent class to all tables.
 *
 * @package     Joomla.Platform
 * @subpackage  Table
 * @link        http://docs.joomla.org/JTable
 * @since       11.1
 * @tutorial	Joomla.Platform/jtable.cls
 */
abstract class JTable extends JObject
{
	/**
	 * Include paths for searching for JTable classes.
	 *
	 * @var    array
	 * @since  12.1
	 */
	private static $_includePaths = array();

	/**
	 * Name of the database table to model.
	 *
	 * @var    string
	 * @since  11.1
	 */
	protected $_tbl = '';

	/**
	 * Name of the primary key field in the table.
	 *
	 * @var    string
	 * @since  11.1
	 */
	protected $_tbl_key = '';

	/**
	 * JDatabaseDriver object.
	 *
	 * @var    JDatabaseDriver
	 * @since  11.1
	 */
	protected $_db;

	/**
	 * Should rows be tracked as ACL assets?
	 *
	 * @var    boolean
	 * @since  11.1
	 */
	protected $_trackAssets = false;

	/**
	 * The rules associated with this record.
	 *
	 * @var    JAccessRules  A JAccessRules object.
	 * @since  11.1
	 */
	protected $_rules;

	/**
	 * Indicator that the tables have been locked.
	 *
	 * @var    boolean
	 * @since  11.1
	 */
	protected $_locked = false;

	/**
	 * Object constructor to set table and key fields.  In most cases this will
	 * be overridden by child classes to explicitly set the table and key fields
	 * for a particular database table.
	 *
	 * @param   string           $table  Name of the table to model.
	 * @param   string           $key    Name of the primary key field in the table.
	 * @param   JDatabaseDriver  $db     JDatabaseDriver object.
	 *
	 * @since   11.1
	 */
	public function __construct($table, $key, $db)
	{
		// Set internal variables.
		$this->_tbl = $table;
		$this->_tbl_key = $key;
		$this->_db = $db;

		// Initialise the table properties.
		$fields = $this->getFields();
		if ($fields)
		{
			foreach ($fields as $name => $v)
			{
				// Add the field if it is not already present.
				if (!property_exists($this, $name))
				{
					$this->$name = null;
				}
			}
		}

		// If we are tracking assets, make sure an access field exists and initially set the default.
		if (property_exists($this, 'asset_id'))
		{
			$this->_trackAssets = true;
		}

		// If the access property exists, set the default.
		if (property_exists($this, 'access'))
		{
			$this->access = (int) JFactory::getConfig()->get('access');
		}
	}

	/**
	 * Get the columns from database table.
	 *
	 * @return  mixed  An array of the field names, or false if an error occurs.
	 *
	 * @since   11.1
	 * @throws  UnexpectedValueException
	 */
	public function getFields()
	{
		static $cache = null;

		if ($cache === null)
		{
			// Lookup the fields for this table only once.
			$name = $this->_tbl;
			$fields = $this->_db->getTableColumns($name, false);

			if (empty($fields))
			{
				throw new UnexpectedValueException(sprintf('No columns found for %s table', $name));
			}
			$cache = $fields;
		}

		return $cache;
	}

	/**
	 * Static method to get an instance of a JTable class if it can be found in
	 * the table include paths.  To add include paths for searching for JTable
	 * classes @see JTable::addIncludePath().
	 *
	 * @param   string  $type    The type (name) of the JTable class to get an instance of.
	 * @param   string  $prefix  An optional prefix for the table class name.
	 * @param   array   $config  An optional array of configuration values for the JTable object.
	 *
	 * @return  mixed    A JTable object if found or boolean false if one could not be found.
	 *
	 * @link    http://docs.joomla.org/JTable/getInstance
	 * @since   11.1
	 */
	public static function getInstance($type, $prefix = 'JTable', $config = array())
	{
		// Sanitize and prepare the table class name.
		$type = preg_replace('/[^A-Z0-9_\.-]/i', '', $type);
		$tableClass = $prefix . ucfirst($type);

		// Only try to load the class if it doesn't already exist.
		if (!class_exists($tableClass))
		{
			// Search for the class file in the JTable include paths.
			$path = JPath::find(self::addIncludePath(), strtolower($type) . '.php');
			if ($path)
			{
				// Import the class file.
				include_once $path;

				// If we were unable to load the proper class, raise a warning and return false.
				if (!class_exists($tableClass))
				{
					JLog::add(JText::sprintf('JLIB_DATABASE_ERROR_CLASS_NOT_FOUND_IN_FILE', $tableClass), JLog::WARNING, 'jerror');
					return false;
				}
			}
			else
			{
				// If we were unable to find the class file in the JTable include paths, raise a warning and return false.
				JLog::add(JText::sprintf('JLIB_DATABASE_ERROR_NOT_SUPPORTED_FILE_NOT_FOUND', $type), JLog::WARNING, 'jerror');
				return false;
			}
		}

		// If a database object was passed in the configuration array use it, otherwise get the global one from JFactory.
		$db = isset($config['dbo']) ? $config['dbo'] : JFactory::getDbo();

		// Instantiate a new table class and return it.
		return new $tableClass($db);
	}

	/**
	 * Add a filesystem path where JTable should search for table class files.
	 * You may either pass a string or an array of paths.
	 *
	 * @param   mixed  $path  A filesystem path or array of filesystem paths to add.
	 *
	 * @return  array  An array of filesystem paths to find JTable classes in.
	 *
	 * @link    http://docs.joomla.org/JTable/addIncludePath
	 * @since   11.1
	 */
	public static function addIncludePath($path = null)
	{
		// If the internal paths have not been initialised, do so with the base table path.
		if (empty(self::$_includePaths))
		{
			self::$_includePaths = array(__DIR__);
		}

		// Convert the passed path(s) to add to an array.
		settype($path, 'array');

		// If we have new paths to add, do so.
		if (!empty($path) && !in_array($path, self::$_includePaths))
		{
			// Check and add each individual new path.
			foreach ($path as $dir)
			{
				// Sanitize path.
				$dir = trim($dir);

				// Add to the front of the list so that custom paths are searched first.
				array_unshift(self::$_includePaths, $dir);
			}
		}

		return self::$_includePaths;
	}

	/**
	 * Method to compute the default name of the asset.
	 * The default name is in the form table_name.id
	 * where id is the value of the primary key of the table.
	 *
	 * @return  string
	 *
	 * @since   11.1
	 */
	protected function _getAssetName()
	{
		$k = $this->_tbl_key;
		return $this->_tbl . '.' . (int) $this->$k;
	}

	/**
	 * Method to return the title to use for the asset table.  In
	 * tracking the assets a title is kept for each asset so that there is some
	 * context available in a unified access manager.  Usually this would just
	 * return $this->title or $this->name or whatever is being used for the
	 * primary name of the row. If this method is not overridden, the asset name is used.
	 *
	 * @return  string  The string to use as the title in the asset table.
	 *
	 * @link    http://docs.joomla.org/JTable/getAssetTitle
	 * @since   11.1
	 */
	protected function _getAssetTitle()
	{
		return $this->_getAssetName();
	}

	/**
	 * Method to get the parent asset under which to register this one.
	 * By default, all assets are registered to the ROOT node with ID,
	 * which will default to 1 if none exists.
	 * The extended class can define a table and id to lookup.  If the
	 * asset does not exist it will be created.
	 *
	 * @param   JTable   $table  A JTable object for the asset parent.
	 * @param   integer  $id     Id to look up
	 *
	 * @return  integer
	 *
	 * @since   11.1
	 */
	protected function _getAssetParentId($table = null, $id = null)
	{
		// For simple cases, parent to the asset root.
		$assets = self::getInstance('Asset', 'JTable', array('dbo' => $this->getDbo()));
		$rootId = $assets->getRootId();
		if (!empty($rootId))
		{
			return $rootId;
		}

		return 1;
	}

	/**
	 * Method to get the database table name for the class.
	 *
	 * @return  string  The name of the database table being modeled.
	 *
	 * @since   11.1
	 *
	 * @link    http://docs.joomla.org/JTable/getTableName
	 */
	public function getTableName()
	{
		return $this->_tbl;
	}

	/**
	 * Method to get the primary key field name for the table.
	 *
	 * @return  string  The name of the primary key for the table.
	 *
	 * @link    http://docs.joomla.org/JTable/getKeyName
	 * @since   11.1
	 */
	public function getKeyName()
	{
		return $this->_tbl_key;
	}

	/**
	 * Method to get the JDatabaseDriver object.
	 *
	 * @return  JDatabaseDriver  The internal database driver object.
	 *
	 * @link    http://docs.joomla.org/JTable/getDBO
	 * @since   11.1
	 */
	public function getDbo()
	{
		return $this->_db;
	}

	/**
	 * Method to set the JDatabaseDriver object.
	 *
	 * @param   JDatabaseDriver  $db  A JDatabaseDriver object to be used by the table object.
	 *
	 * @return  boolean  True on success.
	 *
	 * @link    http://docs.joomla.org/JTable/setDBO
	 * @since   11.1
	 */
	public function setDBO(JDatabaseDriver $db)
	{
		$this->_db = $db;

		return true;
	}

	/**
	 * Method to set rules for the record.
	 *
	 * @param   mixed  $input  A JAccessRules object, JSON string, or array.
	 *
	 * @return  void
	 *
	 * @since   11.1
	 */
	public function setRules($input)
	{
		if ($input instanceof JAccessRules)
		{
			$this->_rules = $input;
		}
		else
		{
			$this->_rules = new JAccessRules($input);
		}
	}

	/**
	 * Method to get the rules for the record.
	 *
	 * @return  JAccessRules object
	 *
	 * @since   11.1
	 */
	public function getRules()
	{
		return $this->_rules;
	}

	/**
	 * Method to reset class properties to the defaults set in the class
	 * definition. It will ignore the primary key as well as any private class
	 * properties.
	 *
	 * @return  void
	 *
	 * @link    http://docs.joomla.org/JTable/reset
	 * @since   11.1
	 */
	public function reset()
	{
		// Get the default values for the class from the table.
		foreach ($this->getFields() as $k => $v)
		{
			// If the property is not the primary key or private, reset it.
			if ($k != $this->_tbl_key && (strpos($k, '_') !== 0))
			{
				$this->$k = $v->Default;
			}
		}
	}

	/**
	 * Method to bind an associative array or object to the JTable instance.This
	 * method only binds properties that are publicly accessible and optionally
	 * takes an array of properties to ignore when binding.
	 *
	 * @param   mixed  $src     An associative array or object to bind to the JTable instance.
	 * @param   mixed  $ignore  An optional array or space separated list of properties to ignore while binding.
	 *
	 * @return  boolean  True on success.
	 *
	 * @link    http://docs.joomla.org/JTable/bind
	 * @since   11.1
	 * @throws  UnexpectedValueException
	 */
	public function bind($src, $ignore = array())
	{
		// If the source value is not an array or object return false.
		if (!is_object($src) && !is_array($src))
		{
			throw new InvalidArgumentException(sprintf('%s::bind(*%s*)', get_class($this), gettype($src)));
		}

		// If the source value is an object, get its accessible properties.
		if (is_object($src))
		{
			$src = get_object_vars($src);
		}

		// If the ignore value is a string, explode it over spaces.
		if (!is_array($ignore))
		{
			$ignore = explode(' ', $ignore);
		}

		// Bind the source value, excluding the ignored fields.
		foreach ($this->getProperties() as $k => $v)
		{
			// Only process fields not in the ignore array.
			if (!in_array($k, $ignore))
			{
				if (isset($src[$k]))
				{
					$this->$k = $src[$k];
				}
			}
		}

		return true;
	}

	/**
	 * Method to load a row from the database by primary key and bind the fields
	 * to the JTable instance properties.
	 *
	 * @param   mixed    $keys   An optional primary key value to load the row by, or an array of fields to match.  If not
	 *                           set the instance property value is used.
	 * @param   boolean  $reset  True to reset the default values before loading the new row.
	 *
	 * @return  boolean  True if successful. False if row not found.
	 *
	 * @link    http://docs.joomla.org/JTable/load
	 * @since   11.1
	 * @throws  RuntimeException
	 * @throws  UnexpectedValueException
	 */
	public function load($keys = null, $reset = true)
	{
		if (empty($keys))
		{
			// If empty, use the value of the current key
			$keyName = $this->_tbl_key;
			$keyValue = $this->$keyName;

			// If empty primary key there's is no need to load anything
			if (empty($keyValue))
			{
				return true;
			}

			$keys = array($keyName => $keyValue);
		}
		elseif (!is_array($keys))
		{
			// Load by primary key.
			$keys = array($this->_tbl_key => $keys);
		}

		if ($reset)
		{
			$this->reset();
		}

		// Initialise the query.
		$query = $this->_db->getQuery(true)
			->select('*')
			->from($this->_tbl);
		$fields = array_keys($this->getProperties());

		foreach ($keys as $field => $value)
		{
			// Check that $field is in the table.
			if (!in_array($field, $fields))
			{
				throw new UnexpectedValueException(sprintf('Missing field in database: %s &#160; %s.', get_class($this), $field));
			}
			// Add the search tuple to the query.
			$query->where($this->_db->quoteName($field) . ' = ' . $this->_db->quote($value));
		}

		$this->_db->setQuery($query);

		$row = $this->_db->loadAssoc();

		// Check that we have a result.
		if (empty($row))
		{
			return false;
		}

		// Bind the object with the row and return.
		return $this->bind($row);
	}

	/**
	 * Method to perform sanity checks on the JTable instance properties to ensure
	 * they are safe to store in the database.  Child classes should override this
	 * method to make sure the data they are storing in the database is safe and
	 * as expected before storage.
	 *
	 * @return  boolean  True if the instance is sane and able to be stored in the database.
	 *
	 * @link    http://docs.joomla.org/JTable/check
	 * @since   11.1
	 */
	public function check()
	{
		return true;
	}

	/**
	 * Method to store a row in the database from the JTable instance properties.
	 * If a primary key value is set the row with that primary key value will be
	 * updated with the instance property values.  If no primary key value is set
	 * a new row will be inserted into the database with the properties from the
	 * JTable instance.
	 *
	 * @param   boolean  $updateNulls  True to update fields even if they are null.
	 *
	 * @return  boolean  True on success.
	 *
	 * @link    http://docs.joomla.org/JTable/store
	 * @since   11.1
	 */
	public function store($updateNulls = false)
	{
		$k = $this->_tbl_key;
		if (!empty($this->asset_id))
		{
			$currentAssetId = $this->asset_id;
		}

		if (0 == $this->$k)
		{
			$this->$k = null;
		}

		// The asset id field is managed privately by this class.
		if ($this->_trackAssets)
		{
			unset($this->asset_id);
		}

		// If a primary key exists update the object, otherwise insert it.
		if ($this->$k)
		{
			$this->_db->updateObject($this->_tbl, $this, $this->_tbl_key, $updateNulls);
		}
		else
		{
			$this->_db->insertObject($this->_tbl, $this, $this->_tbl_key);
		}

		// If the table is not set to track assets return true.
		if (!$this->_trackAssets)
		{
			return true;
		}

		if ($this->_locked)
		{
			$this->_unlock();
		}

		/*
		 * Asset Tracking
		 */

		$parentId = $this->_getAssetParentId();
		$name = $this->_getAssetName();
		$title = $this->_getAssetTitle();

		$asset = self::getInstance('Asset', 'JTable', array('dbo' => $this->getDbo()));
		$asset->loadByName($name);

		// Re-inject the asset id.
		$this->asset_id = $asset->id;

		// Check for an error.
		$error = $asset->getError();
		if ($error)
		{
			$this->setError($error);
			return false;
		}

		// Specify how a new or moved node asset is inserted into the tree.
		if (empty($this->asset_id) || $asset->parent_id != $parentId)
		{
			$asset->setLocation($parentId, 'last-child');
		}

		// Prepare the asset to be stored.
		$asset->parent_id = $parentId;
		$asset->name = $name;
		$asset->title = $title;

		if ($this->_rules instanceof JAccessRules)
		{
			$asset->rules = (string) $this->_rules;
		}

		if (!$asset->check() || !$asset->store($updateNulls))
		{
			$this->setError($asset->getError());
			return false;
		}

		// Create an asset_id or heal one that is corrupted.
		if (empty($this->asset_id) || ($currentAssetId != $this->asset_id && !empty($this->asset_id)))
		{
			// Update the asset_id field in this table.
			$this->asset_id = (int) $asset->id;

			$query = $this->_db->getQuery(true)
				->update($this->_db->quoteName($this->_tbl))
				->set('asset_id = ' . (int) $this->asset_id)
				->where($this->_db->quoteName($k) . ' = ' . (int) $this->$k);
			$this->_db->setQuery($query);

			$this->_db->execute();
		}

		return true;
	}

	/**
	 * Method to provide a shortcut to binding, checking and storing a JTable
	 * instance to the database table.  The method will check a row in once the
	 * data has been stored and if an ordering filter is present will attempt to
	 * reorder the table rows based on the filter.  The ordering filter is an instance
	 * property name.  The rows that will be reordered are those whose value matches
	 * the JTable instance for the property specified.
	 *
	 * @param   mixed   $src             An associative array or object to bind to the JTable instance.
	 * @param   string  $orderingFilter  Filter for the order updating
	 * @param   mixed   $ignore          An optional array or space separated list of properties
	 *                                   to ignore while binding.
	 *
	 * @return  boolean  True on success.
	 *
	 * @link	http://docs.joomla.org/JTable/save
	 * @since   11.1
	 */
	public function save($src, $orderingFilter = '', $ignore = '')
	{
		// Attempt to bind the source to the instance.
		if (!$this->bind($src, $ignore))
		{
			return false;
		}

		// Run any sanity checks on the instance and verify that it is ready for storage.
		if (!$this->check())
		{
			return false;
		}

		// Attempt to store the properties to the database table.
		if (!$this->store())
		{
			return false;
		}

		// Attempt to check the row in, just in case it was checked out.
		if (!$this->checkin())
		{
			return false;
		}

		// If an ordering filter is set, attempt reorder the rows in the table based on the filter and value.
		if ($orderingFilter)
		{
			$filterValue = $this->$orderingFilter;
			$this->reorder($orderingFilter ? $this->_db->quoteName($orderingFilter) . ' = ' . $this->_db->quote($filterValue) : '');
		}

		// Set the error to empty and return true.
		$this->setError('');

		return true;
	}

	/**
	 * Override parent delete method to delete tags information.
	 *
	 * @param   mixed  $pk  An optional primary key value to delete.  If not set the instance property value is used.
	 *
	 * @return  boolean  True on success.
	 *
	 * @link    http://docs.joomla.org/JTable/delete
	 * @since   11.1
	 * @throws  UnexpectedValueException
	 */
	public function delete($pk = null)
	{
		$k = $this->_tbl_key;
		$pk = (is_null($pk)) ? $this->$k : $pk;

		// If no primary key is given, return false.
		if ($pk === null)
		{
			throw new UnexpectedValueException('Null primary key not allowed.');
		}

		// If tracking assets, remove the asset first.
		if ($this->_trackAssets)
		{
			// Get and the asset name.
			$this->$k = $pk;
			$name = $this->_getAssetName();
			$asset = self::getInstance('Asset');

			if ($asset->loadByName($name))
			{
				if (!$asset->delete())
				{
					$this->setError($asset->getError());
					return false;
				}
			}
			else
			{
				$this->setError($asset->getError());
				return false;
			}
		}

		// Delete the row by primary key.
		$query = $this->_db->getQuery(true)
			->delete($this->_tbl)
			->where($this->_tbl_key . ' = ' . $this->_db->quote($pk));
		$this->_db->setQuery($query);

		// Check for a database error.
		$this->_db->execute();

		return true;
	}

	/**
	 * Method to check a row out if the necessary properties/fields exist.  To
	 * prevent race conditions while editing rows in a database, a row can be
	 * checked out if the fields 'checked_out' and 'checked_out_time' are available.
	 * While a row is checked out, any attempt to store the row by a user other
	 * than the one who checked the row out should be held until the row is checked
	 * in again.
	 *
	 * @param   integer  $userId  The Id of the user checking out the row.
	 * @param   mixed    $pk      An optional primary key value to check out.  If not set
	 *                            the instance property value is used.
	 *
	 * @return  boolean  True on success.
	 *
	 * @link    http://docs.joomla.org/JTable/checkOut
	 * @since   11.1
	 */
	public function checkOut($userId, $pk = null)
	{
		// If there is no checked_out or checked_out_time field, just return true.
		if (!property_exists($this, 'checked_out') || !property_exists($this, 'checked_out_time'))
		{
			return true;
		}

		$k = $this->_tbl_key;
		$pk = (is_null($pk)) ? $this->$k : $pk;

		// If no primary key is given, return false.
		if ($pk === null)
		{
			throw new UnexpectedValueException('Null primary key not allowed.');
		}

		// Get the current time in MySQL format.
		$time = JFactory::getDate()->toSql();

		// Check the row out by primary key.
		$query = $this->_db->getQuery(true)
			->update($this->_tbl)
			->set($this->_db->quoteName('checked_out') . ' = ' . (int) $userId)
			->set($this->_db->quoteName('checked_out_time') . ' = ' . $this->_db->quote($time))
			->where($this->_tbl_key . ' = ' . $this->_db->quote($pk));
		$this->_db->setQuery($query);
		$this->_db->execute();

		// Set table values in the object.
		$this->checked_out = (int) $userId;
		$this->checked_out_time = $time;

		return true;
	}

	/**
	 * Method to check a row in if the necessary properties/fields exist.  Checking
	 * a row in will allow other users the ability to edit the row.
	 *
	 * @param   mixed  $pk  An optional primary key value to check out.  If not set the instance property value is used.
	 *
	 * @return  boolean  True on success.
	 *
	 * @link    http://docs.joomla.org/JTable/checkIn
	 * @since   11.1
	 */
	public function checkIn($pk = null)
	{
		// If there is no checked_out or checked_out_time field, just return true.
		if (!property_exists($this, 'checked_out') || !property_exists($this, 'checked_out_time'))
		{
			return true;
		}

		$k = $this->_tbl_key;
		$pk = (is_null($pk)) ? $this->$k : $pk;

		// If no primary key is given, return false.
		if ($pk === null)
		{
			throw new UnexpectedValueException('Null primary key not allowed.');
		}

		// Check the row in by primary key.
		$query = $this->_db->getQuery(true)
			->update($this->_tbl)
			->set($this->_db->quoteName('checked_out') . ' = 0')
			->set($this->_db->quoteName('checked_out_time') . ' = ' . $this->_db->quote($this->_db->getNullDate()))
			->where($this->_tbl_key . ' = ' . $this->_db->quote($pk));
		$this->_db->setQuery($query);

		// Check for a database error.
		$this->_db->execute();

		// Set table values in the object.
		$this->checked_out = 0;
		$this->checked_out_time = '';

		return true;
	}

	/**
	 * Method to increment the hits for a row if the necessary property/field exists.
	 *
	 * @param   mixed  $pk  An optional primary key value to increment. If not set the instance property value is used.
	 *
	 * @return  boolean  True on success.
	 *
	 * @link    http://docs.joomla.org/JTable/hit
	 * @since   11.1
	 */
	public function hit($pk = null)
	{
		// If there is no hits field, just return true.
		if (!property_exists($this, 'hits'))
		{
			return true;
		}

		$k = $this->_tbl_key;
		$pk = (is_null($pk)) ? $this->$k : $pk;

		// If no primary key is given, return false.
		if ($pk === null)
		{
			return false;
		}

		// Check the row in by primary key.
		$query = $this->_db->getQuery(true)
			->update($this->_tbl)
			->set($this->_db->quoteName('hits') . ' = (' . $this->_db->quoteName('hits') . ' + 1)')
			->where($this->_tbl_key . ' = ' . $this->_db->quote($pk));
		$this->_db->setQuery($query);
		$this->_db->execute();

		// Set table values in the object.
		$this->hits++;

		return true;
	}

	/**
	 * Method to determine if a row is checked out and therefore uneditable by
	 * a user. If the row is checked out by the same user, then it is considered
	 * not checked out -- as the user can still edit it.
	 *
	 * @param   integer  $with     The userid to preform the match with, if an item is checked
	 *                             out by this user the function will return false.
	 * @param   integer  $against  The userid to perform the match against when the function
	 *                             is used as a static function.
	 *
	 * @return  boolean  True if checked out.
	 *
	 * @link    http://docs.joomla.org/JTable/isCheckedOut
	 * @since   11.1
	 */
	public function isCheckedOut($with = 0, $against = null)
	{
		// Handle the non-static case.
		if (isset($this) && ($this instanceof JTable) && is_null($against))
		{
			$against = $this->get('checked_out');
		}

		// The item is not checked out or is checked out by the same user.
		if (!$against || ($against == $with))
		{
			return false;
		}

		$db = JFactory::getDbo();
		$db->setQuery('SELECT COUNT(userid) FROM ' . $db->quoteName('#__session') . ' WHERE ' . $db->quoteName('userid') . ' = ' . (int) $against);
		$checkedOut = (boolean) $db->loadResult();

		// If a session exists for the user then it is checked out.
		return $checkedOut;
	}

	/**
	 * Method to get the next ordering value for a group of rows defined by an SQL WHERE clause.
	 * This is useful for placing a new item last in a group of items in the table.
	 *
	 * @param   string  $where  WHERE clause to use for selecting the MAX(ordering) for the table.
	 *
	 * @return  mixed  Boolean false an failure or the next ordering value as an integer.
	 *
	 * @link    http://docs.joomla.org/JTable/getNextOrder
	 * @since   11.1
	 */
	public function getNextOrder($where = '')
	{
		// If there is no ordering field set an error and return false.
		if (!property_exists($this, 'ordering'))
		{
			throw new UnexpectedValueException(sprintf('%s does not support ordering.', get_class($this)));
		}

		// Get the largest ordering value for a given where clause.
		$query = $this->_db->getQuery(true)
			->select('MAX(ordering)')
			->from($this->_tbl);

		if ($where)
		{
			$query->where($where);
		}

		$this->_db->setQuery($query);
		$max = (int) $this->_db->loadResult();

		// Return the largest ordering value + 1.
		return ($max + 1);
	}

	/**
	 * Method to compact the ordering values of rows in a group of rows
	 * defined by an SQL WHERE clause.
	 *
	 * @param   string  $where  WHERE clause to use for limiting the selection of rows to compact the ordering values.
	 *
	 * @return  mixed  Boolean  True on success.
	 *
	 * @link    http://docs.joomla.org/JTable/reorder
	 * @since   11.1
	 */
	public function reorder($where = '')
	{
		// If there is no ordering field set an error and return false.
		if (!property_exists($this, 'ordering'))
		{
			throw new UnexpectedValueException(sprintf('%s does not support ordering.', get_class($this)));
		}

		$k = $this->_tbl_key;

		// Get the primary keys and ordering values for the selection.
		$query = $this->_db->getQuery(true)
			->select($this->_tbl_key . ', ordering')
			->from($this->_tbl)
			->where('ordering >= 0')
			->order('ordering');

		// Setup the extra where and ordering clause data.
		if ($where)
		{
			$query->where($where);
		}

		$this->_db->setQuery($query);
		$rows = $this->_db->loadObjectList();

		// Compact the ordering values.
		foreach ($rows as $i => $row)
		{
			// Make sure the ordering is a positive integer.
			if ($row->ordering >= 0)
			{
				// Only update rows that are necessary.
				if ($row->ordering != $i + 1)
				{
					// Update the row ordering field.
					$query = $this->_db->getQuery(true)
						->update($this->_tbl)
						->set('ordering = ' . ($i + 1))
						->where($this->_tbl_key . ' = ' . $this->_db->quote($row->$k));
					$this->_db->setQuery($query);
					$this->_db->execute();
				}
			}
		}

		return true;
	}

	/**
	 * Method to move a row in the ordering sequence of a group of rows defined by an SQL WHERE clause.
	 * Negative numbers move the row up in the sequence and positive numbers move it down.
	 *
	 * @param   integer  $delta  The direction and magnitude to move the row in the ordering sequence.
	 * @param   string   $where  WHERE clause to use for limiting the selection of rows to compact the
	 *                           ordering values.
	 *
	 * @return  mixed    Boolean  True on success.
	 *
	 * @link    http://docs.joomla.org/JTable/move
	 * @since   11.1
	 * @throws  UnexpectedValueException
	 */
	public function move($delta, $where = '')
	{
		// If there is no ordering field set an error and return false.
		if (!property_exists($this, 'ordering'))
		{
			throw new UnexpectedValueException(sprintf('%s does not support ordering.', get_class($this)));
		}

		// If the change is none, do nothing.
		if (empty($delta))
		{
			return true;
		}

		$k = $this->_tbl_key;
		$row = null;
		$query = $this->_db->getQuery(true);

		// Select the primary key and ordering values from the table.
		$query->select($this->_tbl_key . ', ordering')
			->from($this->_tbl);

		// If the movement delta is negative move the row up.
		if ($delta < 0)
		{
			$query->where('ordering < ' . (int) $this->ordering)
				->order('ordering DESC');
		}
		// If the movement delta is positive move the row down.
		elseif ($delta > 0)
		{
			$query->where('ordering > ' . (int) $this->ordering)
				->order('ordering ASC');
		}

		// Add the custom WHERE clause if set.
		if ($where)
		{
			$query->where($where);
		}

		// Select the first row with the criteria.
		$this->_db->setQuery($query, 0, 1);
		$row = $this->_db->loadObject();

		// If a row is found, move the item.
		if (!empty($row))
		{
			// Update the ordering field for this instance to the row's ordering value.
			$query = $this->_db->getQuery(true)
				->update($this->_tbl)
				->set('ordering = ' . (int) $row->ordering)
				->where($this->_tbl_key . ' = ' . $this->_db->quote($this->$k));
			$this->_db->setQuery($query);
			$this->_db->execute();

			// Update the ordering field for the row to this instance's ordering value.
			$query = $this->_db->getQuery(true)
				->update($this->_tbl)
				->set('ordering = ' . (int) $this->ordering)
				->where($this->_tbl_key . ' = ' . $this->_db->quote($row->$k));
			$this->_db->setQuery($query);
			$this->_db->execute();

			// Update the instance value.
			$this->ordering = $row->ordering;
		}
		else
		{
			// Update the ordering field for this instance.
			$query = $this->_db->getQuery(true)
				->update($this->_tbl)
				->set('ordering = ' . (int) $this->ordering)
				->where($this->_tbl_key . ' = ' . $this->_db->quote($this->$k));
			$this->_db->setQuery($query);
			$this->_db->execute();
		}

		return true;
	}

	/**
	 * Method to set the publishing state for a row or list of rows in the database
	 * table.  The method respects checked out rows by other users and will attempt
	 * to checkin rows that it can after adjustments are made.
	 *
	 * @param   mixed    $pks     An optional array of primary key values to update.
	 *                            If not set the instance property value is used.
	 * @param   integer  $state   The publishing state. eg. [0 = unpublished, 1 = published]
	 * @param   integer  $userId  The user id of the user performing the operation.
	 *
	 * @return  boolean  True on success; false if $pks is empty.
	 *
	 * @link    http://docs.joomla.org/JTable/publish
	 * @since   11.1
	 */
	public function publish($pks = null, $state = 1, $userId = 0)
	{
		$k = $this->_tbl_key;

		// Sanitize input.
		JArrayHelper::toInteger($pks);
		$userId = (int) $userId;
		$state = (int) $state;

		// If there are no primary keys set check to see if the instance key is set.
		if (empty($pks))
		{
			if ($this->$k)
			{
				$pks = array($this->$k);
			}
			// Nothing to set publishing state on, return false.
			else
			{
				return false;
			}
		}

		// Update the publishing state for rows with the given primary keys.
		$query = $this->_db->getQuery(true)
			->update($this->_tbl)
			->set('published = ' . (int) $state);

		// Determine if there is checkin support for the table.
		if (property_exists($this, 'checked_out') || property_exists($this, 'checked_out_time'))
		{
			$query->where('(checked_out = 0 OR checked_out = ' . (int) $userId . ')');
			$checkin = true;
		}
		else
		{
			$checkin = false;
		}

		// Build the WHERE clause for the primary keys.
		$query->where($k . ' = ' . implode(' OR ' . $k . ' = ', $pks));

		$this->_db->setQuery($query);
		$this->_db->execute();

		// If checkin is supported and all rows were adjusted, check them in.
		if ($checkin && (count($pks) == $this->_db->getAffectedRows()))
		{
			// Checkin the rows.
			foreach ($pks as $pk)
			{
				$this->checkin($pk);
			}
		}

		// If the JTable instance value is in the list of primary keys that were set, set the instance.
		if (in_array($this->$k, $pks))
		{
			$this->published = $state;
		}

		$this->setError('');
		return true;
	}

	/**
	 * Method to lock the database table for writing.
	 *
	 * @return  boolean  True on success.
	 *
	 * @since   11.1
	 * @throws  RuntimeException
	 */
	protected function _lock()
	{
		$this->_db->lockTable($this->_tbl);
		$this->_locked = true;

		return true;
	}

	/**
	 * Method to unlock the database table for writing.
	 *
	 * @return  boolean  True on success.
	 *
	 * @since   11.1
	 */
	protected function _unlock()
	{
		$this->_db->unlockTables();
		$this->_locked = false;

		return true;
	}
}