Order student search by custom _pppm field when ordering by price

gistfile1.txt

add_filter( 'propertyhive_get_search_results_ordering_args', 'order_students_by_pppm' );
function order_students_by_pppm($args)
{
	if ( 
		( !isset($_REQUEST['department']) && get_option( 'propertyhive_primary_department', '' ) == 'student' )
		||
		( isset($_REQUEST['department']) && $_REQUEST['department'] == 'student' )
	)
	{
		// if searching student properties
		if ( isset($args['meta_key']) && $args['meta_key'] == '_price_actual' )
		{
			// change to _pppm field
			$args['meta_key'] = '_pppm';
		}
	}
	
	return $args;
}