/**
  * Gets an array of CourseCommentDig objects which contain a foreign key that references this object.
  *
  * If this collection has already been initialized with an identical Criteria, it returns the collection.
  * Otherwise if this CourseComment has previously been saved, it will retrieve
  * related CourseCommentDigs from storage. If this CourseComment is new, it will return
  * an empty collection or the current collection, the criteria is ignored on a new object.
  *
  * @param      PropelPDO $con
  * @param      Criteria $criteria
  * @return     array CourseCommentDig[]
  * @throws     PropelException
  */
 public function getCourseCommentDigs($criteria = null, PropelPDO $con = null)
 {
     if ($criteria === null) {
         $criteria = new Criteria(CourseCommentPeer::DATABASE_NAME);
     } elseif ($criteria instanceof Criteria) {
         $criteria = clone $criteria;
     }
     if ($this->collCourseCommentDigs === null) {
         if ($this->isNew()) {
             $this->collCourseCommentDigs = array();
         } else {
             $criteria->add(CourseCommentDigPeer::COMMENT_ID, $this->id);
             CourseCommentDigPeer::addSelectColumns($criteria);
             $this->collCourseCommentDigs = CourseCommentDigPeer::doSelect($criteria, $con);
         }
     } else {
         // criteria has no effect for a new object
         if (!$this->isNew()) {
             // the following code is to determine if a new query is
             // called for.  If the criteria is the same as the last
             // one, just return the collection.
             $criteria->add(CourseCommentDigPeer::COMMENT_ID, $this->id);
             CourseCommentDigPeer::addSelectColumns($criteria);
             if (!isset($this->lastCourseCommentDigCriteria) || !$this->lastCourseCommentDigCriteria->equals($criteria)) {
                 $this->collCourseCommentDigs = CourseCommentDigPeer::doSelect($criteria, $con);
             }
         }
     }
     $this->lastCourseCommentDigCriteria = $criteria;
     return $this->collCourseCommentDigs;
 }
 /**
 * Retrieve object using using composite pkey values.
 * @param      string $ip
   @param      int $comment_id
   
 * @param      PropelPDO $con
 * @return     CourseCommentDig
 */
 public static function retrieveByPK($ip, $comment_id, PropelPDO $con = null)
 {
     $key = serialize(array((string) $ip, (string) $comment_id));
     if (null !== ($obj = CourseCommentDigPeer::getInstanceFromPool($key))) {
         return $obj;
     }
     if ($con === null) {
         $con = Propel::getConnection(CourseCommentDigPeer::DATABASE_NAME, Propel::CONNECTION_READ);
     }
     $criteria = new Criteria(CourseCommentDigPeer::DATABASE_NAME);
     $criteria->add(CourseCommentDigPeer::IP, $ip);
     $criteria->add(CourseCommentDigPeer::COMMENT_ID, $comment_id);
     $v = CourseCommentDigPeer::doSelect($criteria, $con);
     return !empty($v) ? $v[0] : null;
 }