category id check

Question

I have passing category id through xml i'm trying to check it in block file.but it did not work

foreach ($productCollection as $product) {
            //  get product id
       $productIds[]=$this->getProductData($product->getProductId());
    }
    // get category // IDEA:
    $filterCats = explode(',',$this->getData('parentcat'));
    // filter bestselling products using category id
    if($filterCats != NULL){
    $collection      = $objectManager->create('\Magento\Catalog\Model\ResourceModel\Product\Collection')->addIdFilter($productIds)->addCategoriesFilter(array('in' => $filterCats));
     }

     $collection      = $objectManager->create('\Magento\Catalog\Model\ResourceModel\Product\Collection')->addIdFilter($productIds);

xml

  <block class="Mageplaza\Productslider\Block\BestSellerProducts" name="product.slider.bestsellerproducts" template="productslider.phtml" after="banner.block.1">
        <arguments>
            <argument name="products_count" xsi:type="number">8</argument>
            <argument name="margin" xsi:type="string">5</argument>
          <argument name="parentcat" xsi:type="number">2</argument>
            <argument name="heading" xsi:type="string">Best Sellers</argument>
            <argument name="description" xsi:type="string">Here is your Best Sellers description </argument>
        </arguments>
    </block>

Answer 1

According to docks you should use

$this->getParentcat();

see here: https://devdocs.magento.com/guides/v2.0/frontend-dev-guide/layouts/xml-instructions.html (at the bottom)

It will be better for semantic if you name the parameter parent_cat and then use function: $this->getParentCat();

Let me know if it solves the problem ;)