Magento – Out of stock products not showing (Community 1.8)

Magento Core team better look and fix this issue is still exist in 2.2.7 and I fixed it with a plugin in my custom module and I also added a bonus for you; this also allows you to filter products by website and store id

1. Custom/ModuleName/etc/di.xml

<?xml version="1.0"?>
<!--
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
<type name="Magento\Catalog\Model\ResourceModel\Product\Collection">
    <plugin name="instockFilter" type="Custom\ModuleName\Model\Plugin\InstockFilter" />
</type>

</config>

2. configuration = $configuration; $this->stockHelper = $stockHelper; } public function aroundAddFieldToFilter(ProductCollection $subject, \Closure $proceed, $fields, $condition = null) { if ($this->configuration->isShowOutOfStock() != 1) { $this->stockHelper->addInStockFilterToCollection($subject); } if (is_array($fields)) { foreach ($fields as $key => $filter) { if ($filter['attribute'] == 'website_id' && isset($filter['eq'])) { $subject->addWebsiteFilter([$filter['eq']]); unset($fields[$key]); } else if ($filter['attribute'] == 'store_id' && isset($filter['eq'])) { $subject->addStoreFilter($filter['eq']); unset($fields[$key]); } } } return $fields? $proceed($fields, $condition) : $subject; } }`

For anyone else coming here for a solution, I ended up creating a module for this, which is available from here: https://github.com/pkarsai/show-out-of-stock-products-magento2

The problem is – and that's why the solutions available on the web were not working – that modifying getAllowProducts() alone – as Amit suggested – is not enough. Because there is a second check in Magento code, in the Magento\ConfigurableProduct\Plugin\Model\ResourceModel\AttributeInStockOptionSelectBuilder where all entries that are not on stock are removed:

public function afterGetSelect(OptionSelectBuilderInterface $subject, Select $select)
{
    $select->joinInner(
        ['stock' => $this->stockStatusResource->getMainTable()],
        'stock.product_id = entity.entity_id',
        []
    )->where(
        'stock.stock_status = ?',
        \Magento\CatalogInventory\Model\Stock\Status::STATUS_IN_STOCK
    );

    return $select;
}

So we also need to create a plugin that skips this code. Furthermore, if we stop here then we get the swatches for the products that are not on stock, but nothing indicates that they are out-of-stock until the customer tries to put them into the shopping-basket. So we also need code to that displays a crossed-out swatch when the particular configuration is not available.

TL;DR I won't get into many details here because it's a complex issue, but check out my code here for the complete solution: https://github.com/pkarsai/show-out-of-stock-products-magento2