Magento 2 : Sub Categories not Showing in Layared Navigation

Question

I have install Magento 2.1.3 with Porto Theme.

In category page, Few sub category display proper with products count and Faw doesn't appare/display but it has product.

I tried to disable all custom modules and tried to disable Porto Theme but not display other sub-categories.

Following file from vendor/magento/module-catalog-search/Model/Layer/Filter/Category.php

protected function _getItemsData()
{
    /** @var \Magento\CatalogSearch\Model\ResourceModel\Fulltext\Collection $productCollection */
    $productCollection = $this->getLayer()->getProductCollection();
    $optionsFacetedData = $productCollection->getFacetedData('category');
    $category = $this->dataProvider->getCategory();
    $categories = $category->getChildrenCategories();

    $collectionSize = $productCollection->getSize();

    if ($category->getIsActive()) {
        foreach ($categories as $category) {
            if ($category->getIsActive()
                && isset($optionsFacetedData[$category->getId()])
                && $this->isOptionReducesResults($optionsFacetedData[$category->getId()]['count'], $collectionSize)
            ) {
                $this->itemDataBuilder->addItemData(
                    $this->escaper->escapeHtml($category->getName()),
                    $category->getId(),
                    $optionsFacetedData[$category->getId()]['count']
                );
            }
        }
    }

I debug above code and found that, $this->isOptionReducesResults($optionsFacetedData[$category->getId()]['count'], $collectionSize) getting blank so that sub-categories not showing.

Answer 1

Current behaviour implemented in a way, that isOptionReducesResults function checks whether specific Layered Navigation filter reduces the number of results in result set. And if the Specific filter doesn't lead to narrowing down result set - Magento wouldn't show it.

For example, there are three colors: red, green, blue we have 5 configurable products in the result set. 5 of them have red variations, 3 of them green and 1 - blue.

Our LN filters would look like:

• green - (3)
• blue - (1)

*red wouldn't be shown because all the products have this colour variation. And if we will provide filter red - (5), the user could potentially infinitely apply this filter without narrowing down result set.