MC-33086: [Improvement] Apply Event To Category observer

Author: mslabko

app/code/Magento/Catalog/Block/Product/ListProduct.php

@@ -136,7 +136,14 @@ public function getLayer()
      */
     public function getLoadedProductCollection()
     {
-        return $this->_getProductCollection();
+        $collection = $this->_getProductCollection();
+
+        $categoryId = $this->getLayer()->getCurrentCategory()->getId();
+        foreach ($collection as $product) {
+            $product->setData('category_id', $categoryId);
+        }
+
+        return $collection;
     }
 
     /**

app/code/Magento/Catalog/Model/Product.php

@@ -725,9 +725,14 @@ public function getIdBySku($sku)
      */
     public function getCategoryId()
     {
+        if ($this->hasData('category_id')) {
+            return $this->getData('category_id');
+        }
         $category = $this->_registry->registry('current_category');
-        if ($category && in_array($category->getId(), $this->getCategoryIds())) {
-            return $category->getId();
+        $categoryId = $category ? $category->getId() : null;
+        if ($categoryId && in_array($categoryId, $this->getCategoryIds())) {
+            $this->setData('category_id', $categoryId);
+            return $categoryId;
         }
         return false;
     }