Magento 2: It shows me products out of stock

Question

In the product information, going to the next product shows me some that are out of stock.

I have the configuration that there are no products out of stock ...

Edit:

I think the problem comes from here and should filter the products looking at the stock:

  public function getCategoryProductIds($current_category) {
    $category_products = $current_category->getProductCollection()
        ->addAttributeToSelect('*')
        ->addAttributeToFilter('is_saleable', 1, 'left')
        ->addAttributeToSort('position','asc');
    $cat_prod_ids = $category_products->getAllIds();

    return $cat_prod_ids;
}

How do I filter the products in stock?

Template

    <?php
    $porto_helper = $this->helper('Smartwave\Porto\Helper\Data');
    $product_view = $porto_helper->getConfig('porto_settings/product');
    $_helper = $this->helper('Magento\Catalog\Helper\Output');
    $_imagehelper = $this->helper('Magento\Catalog\Helper\Image');
    if(isset($product_view['prev_next']) && $product_view['prev_next']) {
        $_product = $block->getProduct();
        $prev_product = $porto_helper->getPrevProduct($_product);
        $next_product = $porto_helper->getNextProduct($_product);

Helper

public function getPrevProduct($product) {
    $current_category = $product->getCategory();
    if(!$current_category) {
        foreach($product->getCategoryCollection() as $parent_cat) {
            $current_category = $parent_cat;
        }
    }
    if(!$current_category)
        return false;
    $cat_prod_ids = $this->getCategoryProductIds($current_category);
    $_pos = array_search($product->getId(), $cat_prod_ids);
    if (isset($cat_prod_ids[$_pos - 1])) {
        $prev_product = $this->getModel('Magento\Catalog\Model\Product')->load($cat_prod_ids[$_pos - 1]);
        return $prev_product;
    }
    return false;
}
public function getNextProduct($product) {
    $current_category = $product->getCategory();
    if(!$current_category) {
        foreach($product->getCategoryCollection() as $parent_cat) {
            $current_category = $parent_cat;
        }
    }
    if(!$current_category)
        return false;
    $cat_prod_ids = $this->getCategoryProductIds($current_category);
    $_pos = array_search($product->getId(), $cat_prod_ids);
    if (isset($cat_prod_ids[$_pos + 1])) {
        $next_product = $this->getModel('Magento\Catalog\Model\Product')->load($cat_prod_ids[$_pos + 1]);
        return $next_product;
    }
    return false;
}

Answer 1

Assume that you have a product, Now you need to filter your product collection by in stock product.

Magento2 have a function addIsInStockFilterToCollection at Magento\CatalogInventory\Helper\Stock by which you can filter a collectiuon by in stock product.

Edit:

Inject the class at __constuct function

\Magento\CatalogInventory\Helper\Stock

like

   /**
     * @var Magento\CatalogInventory\Helper\Stock
     */
    protected $stockHelper;

    public function __construct(
.....
    \Magento\CatalogInventory\Helper\Stock $stockHelper
....
       ) {

           $this->stockHelper = $stockHelper;
    }

then filter your collection at getCategoryProductIds

public function getCategoryProductIds($current_category) {
    $category_products = $current_category->getProductCollection()
            ->addAttributeToSelect('*')
            ->addAttributeToSort('position', 'asc');
    // add Stock in stock 
    $this->stockHelper->addIsInStockFilterToCollection($collection);

    $cat_prod_ids = $category_products->getAllIds();

    return $cat_prod_ids;
}