protected function getControllerTargetModel($controller)
    {
        switch ($controller) {
            case 'respondent':
                $model = $this->loader->getModels()->getRespondentModel(true);
                $model->applyEditSettings();
                return $model;

            case 'calendar':
                $model = $this->loader->getModels()->createAppointmentModel();
                $this->applySource($model);
                $model->applyEditSettings();
                return $model;

            default:
                return null;
        }
    }