public function getAppointmentFieldValue(\Gems_Agenda_Appointment $appointment, $field)
    {
        switch ($field) {
            case 'gap_id_organization':
                return $appointment->getOrganizationId();

            case 'gap_source':
                return $appointment->getSource();

            case 'gap_id_attended_by':
                return $appointment->getAttendedById();

            case 'gap_id_referred_by':
                return $appointment->getReferredById();

            case 'gap_id_activity':
                return $appointment->getActivityId();

            case 'gap_id_procedure':
                return $appointment->getProcedureId();

            case 'gap_id_location':
                return $appointment->getLocationId();

            case 'gap_subject':
                return $appointment->getSubject();
        }
    }