[Backport] Don't load product collection in review observer

app/code/Magento/Review/Block/Customer/View.php

@@ -3,6 +3,7 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+
 namespace Magento\Review\Block\Customer;
 
 use Magento\Catalog\Model\Product;
@@ -91,6 +92,7 @@ public function __construct(
      * Initialize review id
      *
      * @return void
+     * @SuppressWarnings(PHPMD.RequestAwareBlockMethod)
      */
     protected function _construct()
     {
@@ -160,6 +162,7 @@ public function getRating()
     /**
      * Get rating summary
      *
+     * @deprecated
      * @return array
      */
     public function getRatingSummary()
@@ -201,26 +204,7 @@ public function dateFormat($date)
     }
 
     /**
-     * Get product reviews summary
-     *
-     * @param \Magento\Catalog\Model\Product $product
-     * @param bool $templateType
-     * @param bool $displayIfNoReviews
-     * @return string
-     */
-    public function getReviewsSummaryHtml(
-        \Magento\Catalog\Model\Product $product,
-        $templateType = false,
-        $displayIfNoReviews = false
-    ) {
-        if (!$product->getRatingSummary()) {
-            $this->_reviewFactory->create()->getEntitySummary($product, $this->_storeManager->getStore()->getId());
-        }
-        return parent::getReviewsSummaryHtml($product, $templateType, $displayIfNoReviews);
-    }
-
-    /**
-     * @return string
+     * @inheritDoc
      */
     protected function _toHtml()
     {

app/code/Magento/Review/Block/Product/ReviewRenderer.php

@@ -5,10 +5,13 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+
 namespace Magento\Review\Block\Product;
 
 use Magento\Catalog\Block\Product\ReviewRendererInterface;
 use Magento\Catalog\Model\Product;
+use Magento\Framework\App\ObjectManager;
+use Magento\Review\Model\ReviewSummaryFactory;
 use Magento\Review\Observer\PredispatchReviewObserver;
 
 /**
@@ -33,17 +36,26 @@ class ReviewRenderer extends \Magento\Framework\View\Element\Template implements
      */
     protected $_reviewFactory;
 
+    /**
+     * @var ReviewSummaryFactory
+     */
+    private $reviewSummaryFactory;
+
     /**
      * @param \Magento\Framework\View\Element\Template\Context $context
      * @param \Magento\Review\Model\ReviewFactory $reviewFactory
      * @param array $data
+     * @param ReviewSummaryFactory $reviewSummaryFactory
      */
     public function __construct(
         \Magento\Framework\View\Element\Template\Context $context,
         \Magento\Review\Model\ReviewFactory $reviewFactory,
-        array $data = []
+        array $data = [],
+        ReviewSummaryFactory $reviewSummaryFactory = null
     ) {
         $this->_reviewFactory = $reviewFactory;
+        $this->reviewSummaryFactory = $reviewSummaryFactory ??
+            ObjectManager::getInstance()->get(ReviewSummaryFactory::class);
         parent::__construct($context, $data);
     }
 
@@ -52,7 +64,7 @@ public function __construct(
      *
      * @return string
      */
-    public function isReviewEnabled() : string
+    public function isReviewEnabled(): string
     {
         return $this->_scopeConfig->getValue(
             PredispatchReviewObserver::XML_PATH_REVIEW_ACTIVE,
@@ -68,17 +80,22 @@ public function isReviewEnabled() : string
      * @param bool $displayIfNoReviews
      *
      * @return string
+     * @throws \Magento\Framework\Exception\LocalizedException
+     * @throws \Magento\Framework\Exception\NoSuchEntityException
      */
     public function getReviewsSummaryHtml(
         \Magento\Catalog\Model\Product $product,
         $templateType = self::DEFAULT_VIEW,
         $displayIfNoReviews = false
     ) {
-        if (!$product->getRatingSummary()) {
-            $this->_reviewFactory->create()->getEntitySummary($product, $this->_storeManager->getStore()->getId());
+        if ($product->getRatingSummary() === null) {
+            $this->reviewSummaryFactory->create()->appendSummaryDataToObject(
+                $product,
+                $this->_storeManager->getStore()->getId()
+            );
         }
 
-        if (!$product->getRatingSummary() && !$displayIfNoReviews) {
+        if (null === $product->getRatingSummary() && !$displayIfNoReviews) {
             return '';
         }
         // pick template among available
@@ -101,7 +118,7 @@ public function getReviewsSummaryHtml(
      */
     public function getRatingSummary()
     {
-        return $this->getProduct()->getRatingSummary()->getRatingSummary();
+        return $this->getProduct()->getRatingSummary();
     }
 
     /**
@@ -111,7 +128,7 @@ public function getRatingSummary()
      */
     public function getReviewsCount()
     {
-        return $this->getProduct()->getRatingSummary()->getReviewsCount();
+        return $this->getProduct()->getReviewsCount();
     }
 
     /**

app/code/Magento/Review/Block/View.php

@@ -119,6 +119,7 @@ public function getRating()
     /**
      * Retrieve rating summary for current product
      *
+     * @deprecated
      * @return string
      */
     public function getRatingSummary()
@@ -160,23 +161,4 @@ public function dateFormat($date)
     {
         return $this->formatDate($date, \IntlDateFormatter::LONG);
     }
-
-    /**
-     * Get product reviews summary
-     *
-     * @param \Magento\Catalog\Model\Product $product
-     * @param bool $templateType
-     * @param bool $displayIfNoReviews
-     * @return string
-     */
-    public function getReviewsSummaryHtml(
-        \Magento\Catalog\Model\Product $product,
-        $templateType = false,
-        $displayIfNoReviews = false
-    ) {
-        if (!$product->getRatingSummary()) {
-            $this->_reviewFactory->create()->getEntitySummary($product, $this->_storeManager->getStore()->getId());
-        }
-        return parent::getReviewsSummaryHtml($product, $templateType, $displayIfNoReviews);
-    }
 }

app/code/Magento/Review/Model/ResourceModel/Review/Summary.php

@@ -3,6 +3,7 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+
 namespace Magento\Review\Model\ResourceModel\Review;
 
 use Magento\Framework\Model\AbstractModel;
@@ -73,4 +74,46 @@ public function reAggregate($summary)
         }
         return $this;
     }
+
+    /**
+     * Append review summary fields to product collection
+     *
+     * @param \Magento\Catalog\Model\ResourceModel\Product\Collection $productCollection
+     * @param string $storeId
+     * @param string $entityCode
+     * @return Summary
+     * @throws \Magento\Framework\Exception\LocalizedException
+     */
+    public function appendSummaryFieldsToCollection(
+        \Magento\Catalog\Model\ResourceModel\Product\Collection $productCollection,
+        string $storeId,
+        string $entityCode
+    ) {
+        if (!$productCollection->isLoaded()) {
+            $summaryEntitySubSelect = $this->getConnection()->select();
+            $summaryEntitySubSelect
+                ->from(
+                    ['review_entity' => $this->getTable('review_entity')],
+                    ['entity_id']
+                )->where(
+                    'entity_code = ?',
+                    $entityCode
+                );
+            $joinCond = new \Zend_Db_Expr(
+                "e.entity_id = review_summary.entity_pk_value AND review_summary.store_id = {$storeId}"
+                . " AND review_summary.entity_type = ({$summaryEntitySubSelect})"
+            );
+            $productCollection->getSelect()
+                ->joinLeft(
+                    ['review_summary' => $this->getMainTable()],
+                    $joinCond,
+                    [
+                        'reviews_count' => new \Zend_Db_Expr("IFNULL(review_summary.reviews_count, 0)"),
+                        'rating_summary' => new \Zend_Db_Expr("IFNULL(review_summary.rating_summary, 0)")
+                    ]
+                );
+        }
+
+        return $this;
+    }
 }

app/code/Magento/Review/Model/Review.php

@@ -3,6 +3,7 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+
 namespace Magento\Review\Model;
 
 use Magento\Framework\DataObject;
@@ -100,6 +101,7 @@ class Review extends \Magento\Framework\Model\AbstractModel implements IdentityI
     /**
      * Review model summary
      *
+     * @deprecated Summary factory injected as separate property
      * @var \Magento\Review\Model\Review\Summary
      */
     protected $_reviewSummary;
@@ -214,6 +216,7 @@ public function aggregate()
     /**
      * Get entity summary
      *
+     * @deprecated
      * @param Product $product
      * @param int $storeId
      * @return void
@@ -301,10 +304,12 @@ public function afterDeleteCommit()
     }
 
     /**
-     * Append review summary to product collection
+     * Append review summary data object to product collection
      *
+     * @deprecated
      * @param ProductCollection $collection
      * @return $this
+     * @throws \Magento\Framework\Exception\NoSuchEntityException
      */
     public function appendSummary($collection)
     {
@@ -313,7 +318,7 @@ public function appendSummary($collection)
             $entityIds[] = $item->getEntityId();
         }
 
-        if (sizeof($entityIds) == 0) {
+        if (count($entityIds) === 0) {
             return $this;
         }
 
@@ -356,7 +361,7 @@ public function isAvailableOnStore($store = null)
     {
         $store = $this->_storeManager->getStore($store);
         if ($store) {
-            return in_array($store->getId(), (array) $this->getStores());
+            return in_array($store->getId(), (array)$this->getStores());
         }
         return false;
     }