/**
* Adds filtering for collection to return only in stock products
*
* @param \Magento\Catalog\Model\ResourceModel\Product\Link\Product\Collection $collection
* @return void
*/
public function addInStockFilterToCollection($collection)
{
$manageStock = $this->scopeConfig->getValue(\Magento\CatalogInventory\Model\Configuration::XML_PATH_MANAGE_STOCK, \Magento\Store\Model\ScopeInterface::SCOPE_STORE);
$cond = ['{{table}}.use_config_manage_stock = 0 AND {{table}}.manage_stock=1 AND {{table}}.is_in_stock=1', '{{table}}.use_config_manage_stock = 0 AND {{table}}.manage_stock=0'];
if ($manageStock) {
$cond[] = '{{table}}.use_config_manage_stock = 1 AND {{table}}.is_in_stock=1';
} else {
$cond[] = '{{table}}.use_config_manage_stock = 1';
}
$collection->joinField('inventory_in_stock', 'cataloginventory_stock_item', 'is_in_stock', 'product_id=entity_id', '(' . join(') OR (', $cond) . ')');
}
