Active Record now supports implicitly declared related properties

6 files changed, 200 insertions, 83 deletions

diff --git a/HISTORY b/HISTORY
index f3e6881c..8f6507cc 100644
--- a/HISTORY
+++ b/HISTORY
@@ -5,6 +5,7 @@ CHG: Changed TConditional so that the controls in its template behave like they
 CHG: Active Record many-to-many relationship change from self::HAS_MANY to self::MANY_TO_MANY (Wei)
 ENH: Active Record supports multiple foreign references of the same table (Wei)
 ENH: Added TDbCommand.queryColumn() (Qiang)
+ENH: Active Record now supports implicitly declared related properties (Qiang)
 NEW: Added TDbLogRoute (Qiang)
 NEW: Added TDataRenderer and TItemDataRenderer (Qiang)
 NEW: Ticket#544 - Added TXCache (Wei)
diff --git a/demos/quickstart/protected/pages/Database/ActiveRecord.page b/demos/quickstart/protected/pages/Database/ActiveRecord.page
index cb10d184..d2793fa1 100644
--- a/demos/quickstart/protected/pages/Database/ActiveRecord.page
+++ b/demos/quickstart/protected/pages/Database/ActiveRecord.page
@@ -624,7 +624,7 @@ class TeamRecord extends TActiveRecord
     public $name;
     public $location;
 
-    public $players=array();
+    public $players=array();  // this declaration is no longer needed since v3.1.2
 
     //define the $player member having has many relationship with PlayerRecord
     public static $RELATIONS=array
@@ -650,6 +650,16 @@ The second element is a string <tt>'PlayerRecord'</tt> that corresponds to the
 class name of the <tt>PlayerRecord</tt> class.
 </p>
 
+<div class="note"><b class="note">Note:</b>
+As described in the code comment above, since version <b>3.1.2</b>, related properties no longer
+need to be explicitly declared. By default, they will be implicitly declared according to
+keys of the <tt>$RELATIONS</tt> array. A major benefit of declared related properties implicitly
+is that related objects can be automatically loaded in a lazy way. For example, assume we have
+a <tt>TeamRecord</tt> instance <tt>$team</tt>. We can access the players via <tt>$team->players</tt>,
+even if we have never issued fetch command for players. If <tt>$players</tt> is explicitly declared,
+we will have to use the <tt>with</tt> approach described in the following to fetch the player records.
+</div>
+
 <p id="710022" class="block-content">
 The foreign key constraint of the <tt>Players</tt> table is used to determine the corresponding
 <tt>Teams</tt> table's corresponding key names. This is done automatically handled
@@ -657,9 +667,9 @@ in Active Record by inspecting the <tt>Players</tt> and <tt>Teams</tt> table def
 </p>
 
 <div class="info"><b class="note">Info:</b>
-Since version <b>3.1.2</b>, Active Record supports multiple foreign key 
+Since version <b>3.1.2</b>, Active Record supports multiple foreign key
 references of the same table. Ambiguity between multiple foreign key references to the same table is
-resolved by providing the foreign key column name as the 3rd parameter in the relationship array. 
+resolved by providing the foreign key column name as the 3rd parameter in the relationship array.
 For example, both the following foreign keys <tt>owner_id</tt> and <tt>reporter_id</tt>
 references the same table defined in <tt>UserRecord</tt>.
 <com:TTextHighlighter Language="php" CssClass="source block-content">
@@ -668,8 +678,8 @@ class TicketRecord extends TActiveRecord
      public $owner_id;
 	 public $reporter_id;
 
-     public $owner;
-	 public $reporter;
+     public $owner;     // this declaration is no longer needed since v3.1.2
+	 public $reporter;  // this declaration is no longer needed since v3.1.2
 
 	 public static $RELATION=array
 	 (
@@ -679,7 +689,7 @@ class TicketRecord extends TActiveRecord
 }
 </com:TTextHighlighter>
 This is applicable to relationships including <tt>BELONGS_TO</tt>, <tt>HAS_ONE</tt> and
-<tt>HAS_MANY</tt>. See section <a href="#142021">Self Referenced Association Tables</a> for solving ambiguity of <tt>MANY_TO_MANY</tt> 
+<tt>HAS_MANY</tt>. See section <a href="#142021">Self Referenced Association Tables</a> for solving ambiguity of <tt>MANY_TO_MANY</tt>
 relationships.
 </div>
 
@@ -709,6 +719,16 @@ and other join conditions are not feasible using Active Records. For queries out
 scope of Active Record the <a href="?page=Database.SqlMap">SqlMap Data Mapper</a> may be considered.
 </div>
 
+<div class="info"><b class="info">Info:</b>
+The above <tt>with</tt> approach also works with implicitly declared related properties (introduced
+in version 3.1.2). So what is the difference between the <tt>with</tt> approach and the lazy loading
+approach? Lazy loading means we issue an SQL query if a related object is initially accessed and not ready,
+while the <tt>with</tt> approach queries for the related objects once for all, no matter the related objects
+are accessed or not. The lazy loading approach is very convenient since we do not need to explictly
+load the related objects, while the <tt>with</tt> approach is more efficient if multiple records are
+returned, each with some related objects.
+</div>
+
 <h3 id="142018">Belongs To Relationship</h3>
 <p id="710025" class="block-content">The "has many" relationship in the above section defines a collection of foreign
 objects. In particular, we have that a <tt>TeamRecord</tt> has many (zero or more)
@@ -726,9 +746,9 @@ class PlayerRecord extends TActiveRecord
     public $age;
     public $team_name;
 
-    public $team;
-    public $skills=array();
-    public $profile;
+    public $team;              // this declaration is no longer needed since v3.1.2
+    public $skills=array();    // this declaration is no longer needed since v3.1.2
+    public $profile;           // this declaration is no longer needed since v3.1.2
 
     public static $RELATIONS=array
     (
@@ -785,7 +805,7 @@ class ProfileRecord extends TActiveRecord
     public $player_id;
     public $salary;
 
-    public $player;
+    public $player;  // this declaration is no longer needed since v3.1.2
 
     public static $RELATIONS=array
     (
@@ -830,8 +850,8 @@ class Category extends TActiveRecord
     public $category_name;
     public $parent_cat_id;
 
-    public $parent_category;
-    public $child_categories=array();
+    public $parent_category;            // this declaration is no longer needed since v3.1.2
+    public $child_categories=array();   // this declaration is no longer needed since v3.1.2
 
     public static $RELATIONS=array
     (
@@ -870,7 +890,7 @@ in the <tt>Player_Skills</tt> association table using an inner join.
 </p>
 
 <p id="710035" class="block-content">The Prado Active Record design implements the two stage approach. For the
-<tt>Players</tt>-<tt>Skills</tt> M-N (many-to-many) entity relationship, we 
+<tt>Players</tt>-<tt>Skills</tt> M-N (many-to-many) entity relationship, we
 define a <b>many-to-many</b> relationship in the <tt>PlayerRecord</tt> class and
 in addition we may define a <b>many-to-many</b> relationship in the <tt>SkillRecord</tt> class as well.
 The following sample code defines the complete <tt>SkillRecord</tt> class with a
@@ -885,7 +905,7 @@ class SkillRecord extends TActiveRecord
     public $skill_id;
     public $name;
 
-    public $players=array();
+    public $players=array();    // this declaration is no longer needed since v3.1.2
 
     public static $RELATIONS=array
     (
@@ -910,10 +930,10 @@ of the association table name.
 </p>
 
 <div class="note"><b class="note">Note:</b>
-Prior to version <b>3.1.2</b> (versions up to 3.1.1), the many-to-many relationship was 
+Prior to version <b>3.1.2</b> (versions up to 3.1.1), the many-to-many relationship was
 defined using <tt>self::HAS_MANY</tt>. For version <b>3.1.2</b> onwards, this must be changed
 to <tt>self::MANY_TO_MANY</tt>. This can be done by searching for the <tt>HAS_MANY</tt> in your
-source code and carfully changing the appropriate definitions. 
+source code and carfully changing the appropriate definitions.
 </div>
 
 <p id="710037" class="block-content">
@@ -975,7 +995,7 @@ class Item extends TActiveRecord
 
     //additional foreign item id defined in the association table
     public $related_item_id;
-    public $related_items=array();
+    public $related_items=array();    // this declaration is no longer needed since v3.1.2
 
     public static $RELATIONS=array
     (
@@ -1030,6 +1050,13 @@ PlayerSkillAssocation::finder()->deleteByPk(array('fk1','fk2'));
 </com:TTextHighlighter>
 
 <h2 id="142015">Lazy Loading Related Objects</h2>
+
+<div class="note"><b class="note">Note:</b>
+Implicitly declared related properties introduced in version 3.1.2 automatically have lazy
+loading feature. Therefore, the lazy loading technique described in the following is no longer
+needed in most of the cases, unless you want to manipulate the related objects through getter/setter.
+</div>
+
 <p id="710045" class="block-content">Using the <tt>with_xxx()</tt> methods will load the relationship record on demand. Retrieving the
 related record using lazy loading (that is, only when those related objects are accessed) can be
 achieved by using a feature of the <tt>TComponent</tt> that provides accessor methods. In particular,
diff --git a/framework/Data/ActiveRecord/Relations/TActiveRecordBelongsTo.php b/framework/Data/ActiveRecord/Relations/TActiveRecordBelongsTo.php
index d4ff07e5..805739c1 100644
--- a/framework/Data/ActiveRecord/Relations/TActiveRecordBelongsTo.php
+++ b/framework/Data/ActiveRecord/Relations/TActiveRecordBelongsTo.php
@@ -81,12 +81,11 @@ class TActiveRecordBelongsTo extends TActiveRecordRelation
 

 		$properties = array_keys($fkeys);

 		$fields = array_values($fkeys);

-

 		$indexValues = $this->getIndexValues($properties, $results);

 		$fkObjects = $this->findForeignObjects($fields, $indexValues);

 		$this->populateResult($results,$properties,$fkObjects,$fields);

 	}

-	

+

 	/**

 	 * @return array foreign key field names as key and object properties as value.

 	 * @since 3.1.2

@@ -94,7 +93,7 @@ class TActiveRecordBelongsTo extends TActiveRecordRelation
 	public function getRelationForeignKeys()

 	{

 		$fkObject = $this->getContext()->getForeignRecordFinder();

-		return $this->findForeignKeys($this->getSourceRecord(),$fkObject);		

+		return $this->findForeignKeys($this->getSourceRecord(),$fkObject);

 	}

 

 	/**

@@ -110,7 +109,7 @@ class TActiveRecordBelongsTo extends TActiveRecordRelation
 		{

 			if(count($collections[$hash]) > 1)

 				throw new TActiveRecordException('ar_belongs_to_multiple_result');

-			$source->setColumnValue($prop, $collections[$hash][0]);

+			$source->$prop=$collections[$hash][0];

 		}

 	}

 

diff --git a/framework/Data/ActiveRecord/Relations/TActiveRecordRelation.php b/framework/Data/ActiveRecord/Relations/TActiveRecordRelation.php
index 8e9cc9b5..5bde4898 100644
--- a/framework/Data/ActiveRecord/Relations/TActiveRecordRelation.php
+++ b/framework/Data/ActiveRecord/Relations/TActiveRecordRelation.php
@@ -41,7 +41,7 @@ abstract class TActiveRecordRelation
 	{

 		return $this->_context;

 	}

-	

+

 	/**

 	 * @return TActiveRecordCriteria

 	 */

@@ -58,6 +58,8 @@ abstract class TActiveRecordRelation
 		return $this->getContext()->getSourceRecord();

 	}

 

+	abstract protected function collectForeignObjects(&$results);

+

 	/**

 	 * Dispatch the method calls to the source record finder object. When

 	 * an instance of TActiveRecord or an array of TActiveRecord is returned

@@ -85,7 +87,7 @@ abstract class TActiveRecordRelation
 			array_push($stack,$this); //call it later

 		return $results;

 	}

-	

+

 	/**

 	 * Fetch results for current relationship.

 	 * @return boolean always true.

@@ -125,13 +127,13 @@ abstract class TActiveRecordRelation
 		throw new TActiveRecordException('ar_relations_missing_fk',

 			$tableInfo->getTableFullName(), $matching);

 	}

-	

+

 	/**

 	 * @return array foreign key field names as key and object properties as value.

-	 * @since 3.1.2	 

+	 * @since 3.1.2

 	 */

 	abstract public function getRelationForeignKeys();

-	

+

 	/**

 	 * Find matching foreign key fields from the 3rd element of an entry in TActiveRecord::$RELATION.

 	 * Assume field names consist of [\w-] character sets. Prefix to the field names ending with a dot

@@ -238,7 +240,7 @@ abstract class TActiveRecordRelation
 	{

 		$hash = $this->getObjectHash($source, $properties);

 		$prop = $this->getContext()->getProperty();

-		$source->setColumnValue($prop, isset($collections[$hash]) ? $collections[$hash] : array());

+		$source->$prop=isset($collections[$hash]) ? $collections[$hash] : array();

 	}

 }

 

diff --git a/framework/Data/ActiveRecord/Relations/TActiveRecordRelationContext.php b/framework/Data/ActiveRecord/Relations/TActiveRecordRelationContext.php
index d83aa63a..8bc4362f 100644
--- a/framework/Data/ActiveRecord/Relations/TActiveRecordRelationContext.php
+++ b/framework/Data/ActiveRecord/Relations/TActiveRecordRelationContext.php
@@ -25,46 +25,16 @@
  */

 class TActiveRecordRelationContext

 {

-	/**

-	 * static property name in TActiveRecord that defines the record relationships.

-	 */

-	const RELATIONS_CONST = 'RELATIONS';

-

 	private $_property;

-	private $_sourceRecord;

+	private $_record;

 	private $_relation; //data from an entry of TActiveRecord::$RELATION

 	private $_fkeys;

 

-	public function __construct($source, $property=null)

-	{

-		$this->_sourceRecord=$source;

-		if($property!==null)

-			list($this->_property, $this->_relation) = $this->getSourceRecordRelation($property);

-	}

-

-	/**

-	 * Uses ReflectionClass to obtain the relation details array of a given

-	 * property from the $RELATIONS static property in TActiveRecord.

-	 * @param string relation property name

-	 * @return array array($propertyName, $relation) relation definition.

-	 */

-	protected function getSourceRecordRelation($property)

-	{

-		$property = strtolower($property);

-		foreach($this->getRecordRelationships() as $name => $relation)

-		{

-			if(strtolower($name)===$property)

-				return array($name, $relation);

-		}

-	}

-

-	/**

-	 * @return array the key and values of TActiveRecord::$RELATIONS

-	 */

-	public function getRecordRelationships()

+	public function __construct($record, $property=null, $relation=null)

 	{

-		$class = new ReflectionClass($this->_sourceRecord);

-		return $class->getStaticPropertyValue(self::RELATIONS_CONST);

+		$this->_record=$record;

+		$this->_property=$property;

+		$this->_relation=$relation;

 	}

 

 	/**

@@ -95,7 +65,7 @@ class TActiveRecordRelationContext
 	 */

 	public function getSourceRecord()

 	{

-		return $this->_sourceRecord;

+		return $this->_record;

 	}

 

 	/**

@@ -183,7 +153,7 @@ class TActiveRecordRelationContext
 		if(!$this->hasRecordRelation())

 		{

 			throw new TActiveRecordException('ar_undefined_relation_prop',

-				$property, get_class($this->_sourceRecord), self::RELATIONS_CONST);

+				$this->_property, get_class($this->_record), 'RELATIONS');

 		}

 		if($criteria===null)

 			$criteria = new TActiveRecordCriteria;

@@ -212,7 +182,7 @@ class TActiveRecordRelationContext
 	public function updateAssociatedRecords($updateBelongsTo=false)

 	{

 		$success=true;

-		foreach($this->getRecordRelationships() as $property=>$relation)

+		foreach($this->_record->getRelations() as $property=>$relation)

 		{

 			$belongsTo = $relation[0]==TActiveRecord::BELONGS_TO;

 			if(($updateBelongsTo && $belongsTo) || (!$updateBelongsTo && !$belongsTo))

@@ -220,7 +190,7 @@ class TActiveRecordRelationContext
 				$obj = $this->getSourceRecord();

 				if(!$this->isEmptyFkObject($obj->getColumnValue($property)))

 				{

-					$context = new self($this->getSourceRecord(),$property);

+					$context = new TActiveRecordRelationContext($this->getSourceRecord(),$property,$relation);

 					$success = $context->getRelationHandler()->updateAssociatedRecords() && $success;

 				}

 			}

diff --git a/framework/Data/ActiveRecord/TActiveRecord.php b/framework/Data/ActiveRecord/TActiveRecord.php
index f28b81e4..a3265dc8 100644
--- a/framework/Data/ActiveRecord/TActiveRecord.php
+++ b/framework/Data/ActiveRecord/TActiveRecord.php
@@ -87,6 +87,27 @@ Prado::using('System.Data.ActiveRecord.Relations.TActiveRecordRelationContext');
  * By using column mapping, we can regularize the naming convention of column names
  * in active record.
  *
+ * Since v3.1.2, TActiveRecord enhanced its support to access of foreign objects.
+ * By declaring a public static variable RELATIONS like the following, one can access
+ * the corresponding foreign objects easily:
+ * <code>
+ * class UserRecord extends TActiveRecord
+ * {
+ *     const TABLE='users';
+ *     public static $RELATIONS=array
+ *     (
+ *         'department'=>array(self::BELONGS_TO, 'DepartmentRecord', 'department_id'),
+ *         'contacts'=>array(self::HAS_MANY, 'ContactRecord', 'user_id'),
+ *     );
+ * }
+ * </code>
+ * In the above, the users table is related with departments table (represented by
+ * DepartmentRecord) and contacts table (represented by ContactRecord). Now, given a UserRecord
+ * instance $user, one can access its department and contacts simply by: $user->department and
+ * $user->contacts. No explicit data fetching is needed. Internally, the foreign objects are
+ * fetched in a lazy way, which avoids unnecessary overhead if the foreign objects are not accessed
+ * at all.
+ *
  * @author Wei Zhuo <weizho[at]gmail[dot]com>
  * @version $Id$
  * @package System.Data.ActiveRecord
@@ -99,8 +120,6 @@ abstract class TActiveRecord extends TComponent
 	const HAS_MANY='HAS_MANY';
 	const MANY_TO_MANY='MANY_TO_MANY';
 
-	private static $_columnMapping=array();
-
 	/**
 	 * This static variable defines the column mapping.
 	 * The keys are physical column names as defined in database,
@@ -110,8 +129,7 @@ abstract class TActiveRecord extends TComponent
 	 * @since 3.1.1
 	 */
 	public static $COLUMN_MAPPING=array();
-
-	private static $_relations=array();
+	private static $_columnMapping=array();
 
 	/**
 	 * This static variable defines the relationships.
@@ -121,6 +139,7 @@ abstract class TActiveRecord extends TComponent
 	 * @since 3.1.1
 	 */
 	public static $RELATIONS=array();
+	private static $_relations=array();
 
 	/**
 	 * @var boolean true if this class is read only.
@@ -133,6 +152,12 @@ abstract class TActiveRecord extends TComponent
 	private $_connection;
 
 	/**
+	 * @var array list of foreign objects.
+	 * @since 3.1.2
+	 */
+	private $_foreignObjects=array();
+
+	/**
 	 * Prevent __call() method creating __sleep() when serializing.
 	 */
 	public function __sleep()
@@ -146,6 +171,7 @@ abstract class TActiveRecord extends TComponent
 	public function __wake()
 	{
 		$this->setupColumnMapping();
+		$this->setupRelations();
 	}
 
 	/**
@@ -161,6 +187,49 @@ abstract class TActiveRecord extends TComponent
 		if($connection!==null)
 			$this->_connection=$connection;
 		$this->setupColumnMapping();
+		$this->setupRelations();
+	}
+
+	/**
+	 * Magic method for reading properties.
+	 * This method is overriden to provide read access to the foreign objects via
+	 * the key names declared in the RELATIONS array.
+	 * @param string property name
+	 * @return mixed property value.
+	 * @since 3.1.2
+	 */
+	public function __get($name)
+	{
+		if($this->hasRelation($name) && !$this->canGetProperty($name))
+		{
+			$name2=strtolower($name);
+			if(!isset($this->_foreignObjects[$name2]))
+				$this->fetchResultsFor($name2);
+			if(isset($this->_foreignObjects[$name2]))
+				return $this->_foreignObjects[$name2]===false?null:$this->_foreignObjects[$name2];
+			else
+			{
+				$this->_foreignObjects[$name2]=false;
+				return null;
+			}
+		}
+		return parent::__get($name);
+	}
+
+	/**
+	 * Magic method for writing properties.
+	 * This method is overriden to provide write access to the foreign objects via
+	 * the key names declared in the RELATIONS array.
+	 * @param string property name
+	 * @param mixed property value.
+	 * @since 3.1.2
+	 */
+	public function __set($name,$value)
+	{
+		if($this->hasRelation($name) && !$this->canSetProperty($name))
+			$this->_foreignObjects[strtolower($name)]=$value===null?false:$value;
+		else
+			parent::__set($name,$value);
 	}
 
 	/**
@@ -177,6 +246,22 @@ abstract class TActiveRecord extends TComponent
 	}
 
 	/**
+	 * @since 3.1.2
+	 */
+	private function setupRelations()
+	{
+		$className=get_class($this);
+		if(!isset(self::$_relations[$className]))
+		{
+			$class=new ReflectionClass($className);
+			$relations=array();
+			foreach($class->getStaticPropertyValue('RELATIONS') as $key=>$value)
+				$relations[strtolower($key)]=$value;
+			self::$_relations[$className]=$relations;
+		}
+	}
+
+	/**
 	 * Copies data from an array or another object.
 	 * @throws TActiveRecordException if data is not array or not object.
 	 * @return TActiveRecord current instance.
@@ -569,17 +654,22 @@ abstract class TActiveRecord extends TComponent
 	 * value equal to the $property value.
 	 * @param string relationship/property name corresponding to keys in $RELATION array.
 	 * @param array method call arguments.
-	 * @return TActiveRecordRelation
+	 * @return TActiveRecordRelation, null if the context or the handler doesn't exist
 	 */
 	protected function getRelationHandler($property,$args=array())
 	{
-		$criteria = $this->getCriteria(count($args)>0 ? $args[0] : null, array_slice($args,1));
-		return $this->getRelationContext($property)->getRelationHandler($criteria);
+		if(($context=$this->getRelationContext($property)) !== null)
+		{
+			$criteria = $this->getCriteria(count($args)>0 ? $args[0] : null, array_slice($args,1));
+			return $context->getRelationHandler($criteria);
+		}
+		else
+			return null;
 	}
 
 	/**
 	 * Gets a static copy of the relationship context for given property (a key
-	 * in $RELATION), returns null if invalid relationship. Keeps a null
+	 * in $RELATIONS), returns null if invalid relationship. Keeps a null
 	 * reference to all invalid relations called.
 	 * @param string relationship/property name corresponding to keys in $RELATION array.
 	 * @return TActiveRecordRelationContext object containing information on
@@ -588,14 +678,10 @@ abstract class TActiveRecord extends TComponent
 	 */
 	protected function getRelationContext($property)
 	{
-		$prop = get_class($this).':'.$property;
-		if(!isset(self::$_relations[$prop]))
-		{
-			$context = new TActiveRecordRelationContext($this, $property);
-			//keep a null reference to all non-existing relations called?
-			self::$_relations[$prop] = $context->hasRecordRelation() ? $context : null;
-		}
-		return self::$_relations[$prop];
+		if(($relation=$this->getRelation($property))!==null)
+			return new TActiveRecordRelationContext($this,$property,$relation);
+		else
+			return null;
 	}
 
 	/**
@@ -637,7 +723,8 @@ abstract class TActiveRecord extends TComponent
 	{
 		if( ($context=$this->getRelationContext($property)) !== null)
 			return $context->getRelationHandler()->fetchResultsInto($this);
-		return false;
+		else
+			return false;
 	}
 
 	/**
@@ -780,5 +867,36 @@ abstract class TActiveRecord extends TComponent
 			$columnName=self::$_columnMapping[$className][$columnName];
 		$this->$columnName=$value;
 	}
+
+	/**
+	 * @param string relation property name
+	 * @return array relation definition for the specified property
+	 * @since 3.1.2
+	 */
+	public function getRelation($property)
+	{
+		$className=get_class($this);
+		$property=strtolower($property);
+		return isset(self::$_relations[$className][$property])?self::$_relations[$className][$property]:null;
+	}
+
+	/**
+	 * @return array all relation definitions declared in the AR class
+	 * @since 3.1.2
+	 */
+	public function getRelations()
+	{
+		return self::$_relations[get_class($this)];
+	}
+
+	/**
+	 * @param string AR property name
+	 * @return boolean whether a relation is declared for the specified AR property
+	 * @since 3.1.2
+	 */
+	public function hasRelation($property)
+	{
+		return isset(self::$_relations[get_class($this)][strtolower($property)]);
+	}
 }
 ?>
\ No newline at end of file