public function getSurvey()
    {
        if (false !== $this->_survey) {
            return $this->_survey;
        }
        $surveyId = $this->getSurveyId();

        if ($surveyId) {
            $this->_survey = $this->tracker->getSurvey($surveyId);
        } else {
            $this->_survey = null;
        }

        return $this->_survey;
    }