[Backport] Fix for #16069: Configurable product price is not displayed if all children are out of stock and even if Display Out of Stock Products is set to "yes" #18776

app/code/Magento/Catalog/Pricing/Render/FinalPriceBox.php

@@ -3,6 +3,7 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+declare(strict_types=1);
 
 namespace Magento\Catalog\Pricing\Render;
 
@@ -64,7 +65,9 @@ public function __construct(
      */
     protected function _toHtml()
     {
-        if (!$this->salableResolver->isSalable($this->getSaleableItem())) {
+        if ($this->isApplySalableCheck($this->getSaleableItem()) &&
+            !$this->salableResolver->isSalable($this->getSaleableItem())
+        ) {
             return '';
         }
 
@@ -86,6 +89,16 @@ protected function _toHtml()
         return $this->wrapResult($result);
     }
 
+    /**
+     * @param SaleableInterface $salableItem
+     * @return bool
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    protected function isApplySalableCheck(SaleableInterface $salableItem): bool
+    {
+        return true;
+    }
+
     /**
      * Check is MSRP applicable for the current product.
      *

app/code/Magento/ConfigurableProduct/Model/ResourceModel/Product/BaseSelectProcessorInterface.php

@@ -0,0 +1,29 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\ConfigurableProduct\Model\ResourceModel\Product;
+
+use Magento\Framework\DB\Select;
+
+/**
+ * Interface BaseSelectProcessorInterface
+ * @api
+ */
+interface BaseSelectProcessorInterface
+{
+    /**
+     * Product table alias
+     */
+    const PRODUCT_TABLE_ALIAS = 'child';
+
+    /**
+     * @param Select $select
+     * @param int $productId
+     * @return Select
+     */
+    public function process(Select $select, int $productId): Select;
+}

app/code/Magento/ConfigurableProduct/Model/ResourceModel/Product/LinkedProductSelectBuilder.php

@@ -3,9 +3,10 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+declare(strict_types=1);
+
 namespace Magento\ConfigurableProduct\Model\ResourceModel\Product;
 
-use Magento\Catalog\Model\ResourceModel\Product\BaseSelectProcessorInterface;
 use Magento\Catalog\Model\ResourceModel\Product\LinkedProductSelectBuilderInterface;
 
 /**
@@ -39,14 +40,14 @@ public function __construct(
     }
 
     /**
-     * {@inheritdoc}
+     * @inheritdoc
      */
-    public function build($productId)
+    public function build($productId): array
     {
         $selects = $this->linkedProductSelectBuilder->build($productId);
 
         foreach ($selects as $select) {
-            $this->baseSelectProcessor->process($select);
+            $this->baseSelectProcessor->process($select, (int)$productId);
         }
 
         return $selects;

app/code/Magento/ConfigurableProduct/Model/ResourceModel/Product/StockStatusBaseSelectProcessor.php

@@ -3,13 +3,17 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+declare(strict_types=1);
+
 namespace Magento\ConfigurableProduct\Model\ResourceModel\Product;
 
 use Magento\Framework\DB\Select;
-use Magento\Catalog\Model\ResourceModel\Product\BaseSelectProcessorInterface;
+use Magento\Framework\App\ObjectManager;
 use Magento\CatalogInventory\Api\StockConfigurationInterface;
 use Magento\CatalogInventory\Model\Stock\Status as StockStatus;
 use Magento\CatalogInventory\Model\ResourceModel\Stock\Status as StockStatusResource;
+use Magento\ConfigurableProduct\Model\ResourceModel\Product\Type\Configurable\StockStatusInterface
+    as StockStatusConfigurableInterface;
 
 /**
  * A Select object processor.
@@ -28,24 +32,35 @@ class StockStatusBaseSelectProcessor implements BaseSelectProcessorInterface
      */
     private $stockStatusResource;
 
+    /**
+     * @var StockStatusConfigurableInterface
+     */
+    private $stockConfigurable;
+
     /**
      * @param StockConfigurationInterface $stockConfig
      * @param StockStatusResource $stockStatusResource
+     * @param StockStatusConfigurableInterface $stockConfigurable
      */
     public function __construct(
         StockConfigurationInterface $stockConfig,
-        StockStatusResource $stockStatusResource
+        StockStatusResource $stockStatusResource,
+        StockStatusConfigurableInterface $stockConfigurable = null
     ) {
         $this->stockConfig = $stockConfig;
         $this->stockStatusResource = $stockStatusResource;
+        $this->stockConfigurable = $stockConfigurable ?:
+            ObjectManager::getInstance()->get(StockStatusConfigurableInterface::class);
     }
 
     /**
-     * {@inheritdoc}
+     * @inheritdoc
      */
-    public function process(Select $select)
+    public function process(Select $select, int $productId): Select
     {
-        if ($this->stockConfig->isShowOutOfStock()) {
+        if ($this->stockConfig->isShowOutOfStock() &&
+            !$this->isAllChildOutOfStock($productId)
+        ) {
             $select->joinInner(
                 ['stock' => $this->stockStatusResource->getMainTable()],
                 sprintf(
@@ -61,4 +76,14 @@ public function process(Select $select)
 
         return $select;
     }
+
+    /**
+     * @param int $productId
+     * @return bool
+     * @throws \Exception
+     */
+    private function isAllChildOutOfStock(int $productId): bool
+    {
+        return $this->stockConfigurable->isAllChildOutOfStock($productId);
+    }
 }

app/code/Magento/ConfigurableProduct/Model/ResourceModel/Product/Type/Configurable/StockStatus.php

@@ -0,0 +1,100 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\ConfigurableProduct\Model\ResourceModel\Product\Type\Configurable;
+
+use Magento\Framework\EntityManager\MetadataPool;
+use Magento\Framework\App\ResourceConnection;
+use Magento\Catalog\Api\Data\ProductInterface;
+use Magento\CatalogInventory\Api\Data\StockStatusInterface as CatalogInventoryStockStatusInterface;
+use Magento\Framework\DB\Adapter\AdapterInterface;
+
+class StockStatus implements StockStatusInterface
+{
+    /**
+     * @var ResourceConnection
+     */
+    private $resource;
+
+    /**
+     * @var MetadataPool
+     */
+    private $metadataPool;
+
+    /**
+     * StockStatus constructor.
+     * @param ResourceConnection $resource
+     * @param MetadataPool $metadataPool
+     */
+    public function __construct(ResourceConnection $resource, MetadataPool $metadataPool)
+    {
+        $this->resource = $resource;
+        $this->metadataPool = $metadataPool;
+    }
+
+    /**
+     * @var array
+     */
+    private $allChildOutOfStockInfo = [];
+
+    /**
+     * @inheritdoc
+     */
+    public function isAllChildOutOfStock(int $productId): bool
+    {
+        if (isset($this->allChildOutOfStockInfo[$productId])) {
+            return $this->allChildOutOfStockInfo[$productId];
+        }
+
+        $statuses = $this->getAllChildStockInfo($productId);
+        $isAllChildOutOfStock = true;
+        foreach ($statuses as $status) {
+            if ($status === CatalogInventoryStockStatusInterface::STATUS_IN_STOCK) {
+                $isAllChildOutOfStock = false;
+                break;
+            }
+        }
+
+        $this->allChildOutOfStockInfo[$productId] = $isAllChildOutOfStock;
+
+        return $this->allChildOutOfStockInfo[$productId];
+    }
+
+    /**
+     * @return AdapterInterface
+     */
+    protected function getConnection(): AdapterInterface
+    {
+        return $this->resource->getConnection();
+    }
+
+    /**
+     * @param int $productId
+     * @return array
+     * @throws \Exception
+     */
+    private function getAllChildStockInfo(int $productId): array
+    {
+        $linkField = $this->metadataPool->getMetadata(ProductInterface::class)->getLinkField();
+        $productTable = $this->resource->getTableName('catalog_product_entity');
+        $productRelationTable = $this->resource->getTableName('catalog_product_relation');
+
+        $select = $this->getConnection()->select()
+            ->from(['parent' => $productTable], '', [])
+            ->joinInner(
+                ['link' => $productRelationTable],
+                "link.parent_id = parent.$linkField",
+                ['id' => 'child_id']
+            )->joinInner(
+                ['stock' => $this->resource->getTableName('cataloginventory_stock_status')],
+                'stock.product_id = link.child_id',
+                ['stock_status']
+            )->where(sprintf('parent.%s = ?', $linkField), $productId);
+
+        return $this->getConnection()->fetchPairs($select);
+    }
+}

app/code/Magento/ConfigurableProduct/Model/ResourceModel/Product/Type/Configurable/StockStatusInterface.php

@@ -0,0 +1,22 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\ConfigurableProduct\Model\ResourceModel\Product\Type\Configurable;
+
+/**
+ * Interface StockStatusInterface
+ * @api
+ */
+interface StockStatusInterface
+{
+    /**
+     * @param int $productId
+     * @return bool
+     * @throws \Exception
+     */
+    public function isAllChildOutOfStock(int $productId): bool;
+}

app/code/Magento/ConfigurableProduct/Pricing/Render/FinalPriceBox.php

@@ -3,6 +3,8 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+declare(strict_types=1);
+
 namespace Magento\ConfigurableProduct\Pricing\Render;
 
 use Magento\Catalog\Model\Product\Pricing\Renderer\SalableResolverInterface;
@@ -16,14 +18,24 @@
 use Magento\Framework\Pricing\Render\RendererPool;
 use Magento\Framework\Pricing\SaleableInterface;
 use Magento\Framework\View\Element\Template\Context;
+use Magento\CatalogInventory\Api\StockConfigurationInterface;
 
+/**
+ * Class FinalPriceBox
+ * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
+ */
 class FinalPriceBox extends \Magento\Catalog\Pricing\Render\FinalPriceBox
 {
     /**
      * @var LowestPriceOptionsProviderInterface
      */
     private $lowestPriceOptionsProvider;
 
+    /**
+     * @var StockConfigurationInterface
+     */
+    private $stockConfig;
+
     /**
      * @param Context $context
      * @param SaleableInterface $saleableItem
@@ -33,8 +45,10 @@ class FinalPriceBox extends \Magento\Catalog\Pricing\Render\FinalPriceBox
      * @param array $data
      * @param LowestPriceOptionsProviderInterface $lowestPriceOptionsProvider
      * @param SalableResolverInterface|null $salableResolver
-     * @param MinimalPriceCalculatorInterface|null $minimalPriceCalculator
+     * @param MinimalPriceCalculatorInterface|null $minPriceCalculator
+     * @param StockConfigurationInterface|null $stockConfig
      * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     * @SuppressWarnings(PHPMD.ExcessiveParameterList)
      */
     public function __construct(
         Context $context,
@@ -45,7 +59,8 @@ public function __construct(
         array $data = [],
         LowestPriceOptionsProviderInterface $lowestPriceOptionsProvider = null,
         SalableResolverInterface $salableResolver = null,
-        MinimalPriceCalculatorInterface $minimalPriceCalculator = null
+        MinimalPriceCalculatorInterface $minPriceCalculator = null,
+        StockConfigurationInterface $stockConfig = null
     ) {
         parent::__construct(
             $context,
@@ -54,18 +69,20 @@ public function __construct(
             $rendererPool,
             $data,
             $salableResolver,
-            $minimalPriceCalculator
+            $minPriceCalculator
         );
         $this->lowestPriceOptionsProvider = $lowestPriceOptionsProvider ?:
             ObjectManager::getInstance()->get(LowestPriceOptionsProviderInterface::class);
+        $this->stockConfig = $stockConfig ?:
+            ObjectManager::getInstance()->get(StockConfigurationInterface::class);
     }
 
     /**
      * Define if the special price should be shown
      *
      * @return bool
      */
-    public function hasSpecialPrice()
+    public function hasSpecialPrice(): bool
     {
         $product = $this->getSaleableItem();
         foreach ($this->lowestPriceOptionsProvider->getProducts($product) as $subProduct) {
@@ -77,4 +94,12 @@ public function hasSpecialPrice()
         }
         return false;
     }
+
+    /**
+     * @inheritdoc
+     */
+    protected function isApplySalableCheck(SaleableInterface $salableItem): bool
+    {
+        return !$this->stockConfig->isShowOutOfStock();
+    }
 }