AC-13363::Category tree in admin is not expanded to show all selected nested categories from level 3

Author: glo60612

app/code/Magento/Catalog/Block/Adminhtml/Category/Checkboxes/Tree.php

@@ -58,6 +58,18 @@ public function setCategoryIds($ids)
             $ids = [(int)$ids];
         }
         $this->_selectedIds = $ids;
+
+        // Pre-compute expanded paths for all selected categories so that
+        // ancestors are marked as expanded before the JSON is generated.
+        $this->_expandedPath = [];
+        if (!empty($ids)) {
+            $collection = $this->_categoryFactory->create()->getCollection();
+            $collection->addAttributeToSelect('path')
+                ->addAttributeToFilter('entity_id', ['in' => $ids]);
+            foreach ($collection as $category) {
+                $this->setExpandedPath($category->getPath());
+            }
+        }
         return $this;
     }
 
@@ -122,4 +134,74 @@ protected function _getNodeJson($node, $level = 1)
         $item['expanded'] = in_array($node->getId(), $this->getExpandedPath());
         return $item;
     }
+
+    /**
+     * Get tree structure
+     *
+     * Ensure that deeply selected categories are present by building the tree
+     * around selected IDs rather than the default 3-level root-only tree.
+     *
+     * @param mixed|null $parenNodeCategory
+     * @return array
+     */
+    public function getTree($parenNodeCategory = null)
+    {
+        // For AJAX child loads, respect the requested parent node
+        if ($parenNodeCategory !== null) {
+            $root = $this->getRoot($parenNodeCategory);
+        } else {
+            $root = empty($this->_selectedIds)
+                ? $this->getRoot($parenNodeCategory)
+                : $this->getRootByIds($this->_selectedIds);
+        }
+
+        $rootArray = $this->_getNodeJson($root);
+        return $rootArray['children'] ?? [];
+    }
+
+    /**
+     * Get tree json
+     *
+     * Ensure that deeply selected categories are present in the JSON output.
+     *
+     * @param mixed|null $parenNodeCategory
+     * @return string
+     */
+    public function getTreeJson($parenNodeCategory = null)
+    {
+        // For AJAX child loads, respect the requested parent node
+        if ($parenNodeCategory !== null) {
+            $root = $this->getRoot($parenNodeCategory);
+        } else {
+            $root = empty($this->_selectedIds)
+                ? $this->getRoot($parenNodeCategory)
+                : $this->getRootByIds($this->_selectedIds);
+        }
+
+        $rootArray = $this->_getNodeJson($root);
+        return $this->_jsonEncoder->encode($rootArray['children'] ?? []);
+    }
+
+    /**
+     * Override parent's implementation to avoid using cached registry root
+     * which might have been built with limited recursion and miss deep nodes.
+     *
+     * @param array $ids
+     * @return \Magento\Framework\Data\Tree\Node|array|null
+     */
+    public function getRootByIds($ids)
+    {
+        $ids = $this->_categoryTree->getExistingCategoryIdsBySpecifiedIds($ids);
+        $tree = $this->_categoryTree->loadByIds($ids);
+        $rootId = \Magento\Catalog\Model\Category::TREE_ROOT_ID;
+        $root = $tree->getNodeById($rootId);
+        if ($root) {
+            $root->setIsVisible(true);
+            if ($root->getId() == \Magento\Catalog\Model\Category::TREE_ROOT_ID) {
+                $root->setName(__('Root'));
+            }
+        }
+        $tree->addCollectionData($this->getCategoryCollection());
+        return $root;
+    }
 }