Prado\Web\UI\WebControls\TReCaptcha::onPreRender PHP Method

    public function onPreRender($param)
    {
        parent::onPreRender($param);
        if ("" == $this->getPublicKey()) {
            throw new TConfigurationException('recaptcha_publickey_unknown');
        }
        if ("" == $this->getPrivateKey()) {
            throw new TConfigurationException('recaptcha_privatekey_unknown');
        }
        // need to register captcha fields so they will be sent back also in callbacks
        $page = $this->getPage();
        $page->registerRequiresPostData($this->getChallengeFieldName());
        $page->registerRequiresPostData($this->getResponseFieldName());
    }