Magento 2 Get Request Param Always Null

Question

I can't seem to get request params from a Data Provider. I've modified Magento\Review\Ui\DataProvider\Product\ReviewDataProvider.php to log (also tried var_dump) the information, but it always returns null.

The following code is from Magento\Review\Ui\DataProvider\Product\ReviewDataProvider.php,

   public function getData()
    {

        $this->getCollection()->addEntityFilter($this->request->getParam('current_product_id', 0))
            ->addStoreData();

        $arrItems = [
            'totalRecords' => $this->getCollection()->getSize(),
            'items' => [],
        ];

        foreach ($this->getCollection() as $item) {
            $arrItems['items'][] = $item->toArray([]);
        }

        return $arrItems;
    }

If I try to var_dump or log $this->request->getParam('current_product_id', 0), the result is null. This is the only point for the Collection to be filtered by the product ID (that I've found). I've also tried $this->getCollection()->getParams(), which shows some parameters, but the current_product_id is not included. Why does this happen and how can I view the request parameter?

Answer 1

In the function getData() in Magento\Review\Ui\DataProvider\Product\ReviewDataProvider.php is called by Magento 2 times. The first call is made by GET to {{domain_admin}}/mui/index/render/?namespace=review_listing&isAjax=true, in which only $this->request->getParams() the namespace variable and isAjax appear. And in the second call is made by POST and receives more parameters. Among them, the current_product_id