/** * @param ExistingReservationSeries $series * @return mixed|null|string */ private function CheckCapacityAndReturnAnyError($series) { foreach ($series->AllResources() as $resource) { if (!$resource->HasMaxParticipants()) { continue; } /** @var $instance Reservation */ foreach ($series->Instances() as $instance) { $numberOfParticipants = count($instance->Participants()); if ($numberOfParticipants > $resource->GetMaxParticipants()) { return Resources::GetInstance()->GetString('MaxParticipantsError', array($resource->GetName(), $resource->GetMaxParticipants())); } } } return null; }