/**
* order by a property (must be set as shown property before)
*
* @param type $uri the property to order by
* @param boolean $asc true if ascending, false if descending
*/
public function setOrderProperty($uri, $asc = true)
{
$this->setOffset(0);
if ($this->_sortTriple == null) {
$orderVar = new Erfurt_Sparql_Query2_Var('order');
$this->_sortTriple = new Erfurt_Sparql_Query2_OptionalGraphPattern(array(new Erfurt_Sparql_Query2_Triple($this->getResourceVar(), new Erfurt_Sparql_Query2_IriRef($uri), $orderVar)));
$this->_resourceQuery->getWhere()->addElement($this->_sortTriple);
$this->_resourceQuery->getOrder()->add($orderVar, $asc ? Erfurt_Sparql_Query2_OrderClause::ASC : Erfurt_Sparql_Query2_OrderClause::DESC);
} else {
$this->_sortTriple->getElement(0)->setP(new Erfurt_Sparql_Query2_IriRef($uri));
if ($asc) {
$this->_resourceQuery->getOrder()->setAsc(0);
} else {
$this->_resourceQuery->getOrder()->setDesc(0);
}
}
$this->invalidate();
}
