[5.0] Filter by category - levels (#39950)

---------

Co-authored-by: Harald Leithner <[email protected]>

Author: brianteeman

administrator/components/com_categories/forms/filter_categories.xml

@@ -63,6 +63,18 @@
 			>
 			<option value="">JOPTION_SELECT_MAX_LEVELS</option>
 		</field>
+
+		<field
+			name="category_id"
+			type="category"
+			label="JOPTION_SELECT_CATEGORY"
+			multiple="true"
+			extension="dynamic"
+			layout="joomla.form.field.list-fancy-select"
+			hint="JOPTION_SELECT_CATEGORY"
+			published="0,1,2"
+			class="js-select-submit-on-change"
+		/>
 	</fields>
 
 	<fields name="list">

administrator/components/com_categories/src/Model/CategoriesModel.php

@@ -16,6 +16,7 @@
 use Joomla\CMS\Language\Associations;
 use Joomla\CMS\MVC\Factory\MVCFactoryInterface;
 use Joomla\CMS\MVC\Model\ListModel;
+use Joomla\CMS\Table\Table;
 use Joomla\Database\DatabaseQuery;
 use Joomla\Database\ParameterType;
 use Joomla\Utilities\ArrayHelper;
@@ -66,6 +67,7 @@ public function __construct($config = [], MVCFactoryInterface $factory = null)
                 'level', 'a.level',
                 'path', 'a.path',
                 'tag',
+                'category_id', 'a.id',
             ];
         }
 
@@ -239,8 +241,31 @@ protected function getListQuery()
                 ->bind(':extension', $extension);
         }
 
-        // Filter on the level.
-        if ($level = (int) $this->getState('filter.level')) {
+        // Filter by categories and by level
+        $categoryId = $this->getState('filter.category_id', []);
+        $level      = $this->getState('filter.level');
+
+        if (!is_array($categoryId)) {
+            $categoryId = $categoryId ? [$categoryId] : [];
+        }
+
+        // Case: Using both categories filter and by level filter
+        if (count($categoryId)) {
+            $categoryTable    = Table::getInstance('Category', 'JTable');
+            $subCatItemsWhere = [];
+
+            foreach ($categoryId as $filterCatId) {
+                $categoryTable->load($filterCatId);
+                $subCatItemsWhere[] = '(' .
+                    ($level ? 'a.level <= ' . ((int) $level + (int) $categoryTable->level - 1) . ' AND ' : '') .
+                    'a.lft >= ' . (int) $categoryTable->lft . ' AND ' .
+                    'a.rgt <= ' . (int) $categoryTable->rgt . ')';
+            }
+
+            $query->where('(' . implode(' OR ', $subCatItemsWhere) . ')');
+
+        // Case: Using only the by level filter
+        } elseif ($level) {
             $query->where($db->quoteName('a.level') . ' <= :level')
                 ->bind(':level', $level, ParameterType::INTEGER);
         }
@@ -355,25 +380,25 @@ protected function getListQuery()
 
         // Group by on Categories for \JOIN with component tables to count items
         $query->group('a.id,
-				a.title,
-				a.alias,
-				a.note,
-				a.published,
-				a.access,
-				a.checked_out,
-				a.checked_out_time,
-				a.created_user_id,
-				a.path,
-				a.parent_id,
-				a.level,
-				a.lft,
-				a.rgt,
-				a.language,
-				l.title,
-				l.image,
-				uc.name,
-				ag.title,
-				ua.name');
+                a.title,
+                a.alias,
+                a.note,
+                a.published,
+                a.access,
+                a.checked_out,
+                a.checked_out_time,
+                a.created_user_id,
+                a.path,
+                a.parent_id,
+                a.level,
+                a.lft,
+                a.rgt,
+                a.language,
+                l.title,
+                l.image,
+                uc.name,
+                ag.title,
+                ua.name');
 
         return $query;
     }

administrator/components/com_categories/src/View/Categories/HtmlView.php

@@ -146,6 +146,10 @@ public function display($tpl = null)
             }
         }
 
+        // If filter by category is active we need to know the extension name to filter the categories
+        $extensionName = $this->escape($this->state->get('filter.extension'));
+        $this->filterForm->setFieldAttribute('category_id', 'extension', $extensionName, 'filter');
+
         parent::display($tpl);
     }