Layered Navigation not showing the right options after overriding product list block

Question

I've successfully override productList block to show my custom filtered product collection like this:

di.xml

<preference for="\Magento\Catalog\Block\Product\ListProduct" type="\Vendor\Module\Block\Product\ListProduct"/>

Vendor\Module\Block\Product\ListProduct

protected function _getProductCollection()
{
    $productCollection = parent::_getProductCollection(); 
    if(isset($_GET['custom_input'])){
      if(!empty($_GET['custom_input']){
        $customInput = $_GET['custom_input'];
        $productCollection = $this->myModuleHelper->filterProduct(customInput, productCollection);
      }
    }
    $this->_productCollection = $productCollection;
    $this->_productCollection->getSize();
    return $proCollection;
}

but the layered navigation options not showing the right option and product count like the image below:

Answer 1

For making the product collection compatible with the layered nevigation you can follow below code -

protected function _getProductCollection() 
{ 
if ($this->_productCollection === null) 
{ 
$layer = $this->getLayer(); 
if ($this->getShowRootCategory()) 
{ 
$this->setCategoryId($this->_storeManager->getStore()->getRootCategoryId()); 
}





        if ($this->_coreRegistry->registry('product')) {
          $categories = $this->_coreRegistry->registry('product')
                    ->getCategoryCollection()->setPage(1, 1)
                    ->load();
          if ($categories->count()) {
              $this->setCategoryId(current($categories->getIterator()));
          }
        }
        $origCategory = null;
        if ($this->getCategoryId()) {
          try {
              $category = $this->categoryRepository->get($this->getCategoryId());
          } catch (\Magento\Framework\Exception\NoSuchEntityException $e) {
              $category = null;
          }
          if ($category) {
              $origCategory = $layer->getCurrentCategory();
              $layer->setCurrentCategory($category);
          }
        }

        $productcollection = $layer->getProductCollection();
        /* you may apply the your custom filter on this product collection */


        $this->_productCollection = $productcollection;
        $this->prepareSortableFieldsByCategory($layer->getCurrentCategory());

        if ($origCategory) {
          $layer->setCurrentCategory($origCategory);
        }
    } 
    $this->_productCollection->getSize();
    return $this->_productCollection;
}

In your code neither you are getting the product collection from layer and nor assigning the same to category. For reference you may follow the core block - Magento\Catalog\Block\Product\ListProduct