恢复以group_slide开头的值

I modify the module revolution slider under prestashop to include the possibility of displaying some slides to certain groups of users. I'm currently blocking on the recovery of select values ​​from the revslider BO.

this recover well in the XHR call the select values

on the other hand it is PHP where I do not see how to do ....

here is the function that inserts the data of the slide.

public function updateSlideFromData($data)
{
    $group = $data['params'];

    if (strpos($group, 'group_slide_') == true) {
        ddd($group);
    }

    $slideID = RevSliderFunctions::getVal($data, "slideid");
    $this->initByID($slideID);

    //treat params
    $params = RevSliderFunctions::getVal($data, "params");
    $params = $this->normalizeParams($params);

    //preserve old data that not included in the given data
    $params = array_merge($this->params, $params);
    //treat layers
    $layers = RevSliderFunctions::getVal($data, "layers");

    if (gettype($layers) == "string") {
        $layersStrip = Tools::stripslashes($layers);
        $layersDecoded = Tools::jsonDecode($layersStrip);
        if (empty($layersDecoded)) {
            $layersDecoded = Tools::jsonDecode($layers);
        }

        $layers = RevSliderFunctions::convertStdClassToArray($layersDecoded);
    }

    if (empty($layers) || gettype($layers) != "array") {
        $layers = array();
    }


    $layers = $this->normalizeLayers($layers);

    $settings = RevSliderFunctions::getVal($data, "settings");

    $arrUpdate = array();
    $arrUpdate["layers"] = Tools::jsonEncode($layers);
    $arrUpdate["params"] = Tools::jsonEncode($params);
    $arrUpdate["settings"] = Tools::jsonEncode($settings);

    $this->db->update(RevSliderGlobals::$table_slides, $arrUpdate, array("id" => $this->id));



    // RevOperations::updateDynamicCaptions();
}

I attempt with a strpos to retrieve only the values ​​that start with group_slide and then inject into my base the values ​​select by separating them with commas, like this: 16,17,18

How?