/**
  * @param Request                $request
  * @param CategoryInterface|null $selectNode
  *
  * @return array|ArrayCollection
  */
 protected function getChildrenCategories(Request $request, $selectNode)
 {
     $parent = $this->findCategory($request->get('id'));
     if (null !== $selectNode) {
         $categories = $this->categoryRepository->getChildrenTreeByParentId($parent->getId(), $selectNode->getId());
     } else {
         $categories = $this->categoryRepository->getChildrenByParentId($parent->getId());
     }
     return $categories;
 }