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<?php
/**
* TActiveRecordHasOne class file.
*
* @author Wei Zhuo <weizhuo[at]gmail[dot]com>
* @link http://www.pradosoft.com/
* @copyright Copyright © 2005-2007 PradoSoft
* @license http://www.pradosoft.com/license/
* @version $Id$
* @package System.Data.ActiveRecord.Relations
*/
/**
* Loads base active record relationship class.
*/
Prado::using('System.Data.ActiveRecord.Relations.TActiveRecordRelation');
/**
* TActiveRecordHasOne models the object relationship that a record (the source object)
* property is an instance of foreign record object having a foreign key
* related to the source object. The HAS_ONE relation is very similar to the
* HAS_MANY relationship (in fact, it is equivalent in the entities relationship point of view).
*
* The difference of HAS_ONE from HAS_MANY is that the foreign object is singular.
* That is, HAS_MANY will return a collection of records while HAS_ONE returns the
* corresponding record.
*
* Consider the <b>entity</b> relationship between a Car and a Engine.
* <code>
* +-----+ +--------+
* | Car | 1 <----- 1 | Engine |
* +-----+ +--------+
* </code>
* Where each engine belongs to only one car, that is, the Engine entity has
* a foreign key to the Car's primary key. We may model
* Engine-Car <b>object</b> relationship as active record as follows.
* <code>
* class CarRecord extends TActiveRecord
* {
* const TABLE='car';
* public $car_id; //primary key
* public $colour;
*
* public $engine; //engine foreign object
*
* protected static $RELATIONS=array
* (
* 'engine' => array(self::HAS_ONE, 'EngineRecord')
* );
*
* public static function finder($className=__CLASS__)
* {
* return parent::finder($className);
* }
* }
* class EngineRecord extends TActiveRecord
* {
* const TABLE='engine';
* public $engine_id;
* public $capacity;
* public $car_id; //foreign key to cars
*
* public static function finder($className=__CLASS__)
* {
* return parent::finder($className);
* }
* }
* </code>
* The static <tt>$RELATIONS</tt> property of CarRecord defines that the
* property <tt>$engine</tt> that will reference an <tt>EngineRecord</tt> instance.
*
* The car record with engine property list may be fetched as follows.
* <code>
* $cars = CarRecord::finder()->with_engine()->findAll();
* </code>
* The method <tt>with_xxx()</tt> (where <tt>xxx</tt> is the relationship property
* name, in this case, <tt>engine</tt>) fetchs the corresponding EngineRecords using
* a second query (not by using a join). The <tt>with_xxx()</tt> accepts the same
* arguments as other finder methods of TActiveRecord, e.g. <tt>with_engine('capacity < ?', 3.8)</tt>.
*
* @author Wei Zhuo <weizho[at]gmail[dot]com>
* @version $Id$
* @package System.Data.ActiveRecord.Relations
* @since 3.1
*/
class TActiveRecordHasOne extends TActiveRecordRelation
{
/**
* Get the foreign key index values from the results and make calls to the
* database to find the corresponding foreign objects.
* @param array original results.
*/
protected function collectForeignObjects(&$results)
{
$fkObject = $this->getContext()->getForeignRecordFinder();
$fkeys = $this->findForeignKeys($fkObject, $this->getSourceRecord());
$properties = array_values($fkeys);
$fields = array_keys($fkeys);
$indexValues = $this->getIndexValues($properties, $results);
$fkObjects = $this->findForeignObjects($fields,$indexValues);
$this->populateResult($results,$properties,$fkObjects,$fields);
}
/**
* Sets the foreign objects to the given property on the source object.
* @param TActiveRecord source object.
* @param array foreign objects.
*/
protected function setObjectProperty($source, $properties, &$collections)
{
$hash = $this->getObjectHash($source, $properties);
$prop = $this->getContext()->getProperty();
if(isset($collections[$hash]) && count($collections[$hash]) > 0)
{
if(count($collections[$hash]) > 1)
throw new TActiveRecordException('ar_belongs_to_multiple_result');
$source->{$prop} = $collections[$hash][0];
}
}
}
?>
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