From 4365453a201a9f14bd8bac77d75078599b5cfca1 Mon Sep 17 00:00:00 2001
From: Alexander Ebert <ebert@woltlab.com>
Date: Sun, 5 Jan 2020 20:08:00 +0100
Subject: [PATCH] Workaround for the search for objects matching multiple tags

---
 .../tagging/TTaggedObjectList.class.php       | 33 +++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 wcfsetup/install/files/lib/system/tagging/TTaggedObjectList.class.php

diff --git a/wcfsetup/install/files/lib/system/tagging/TTaggedObjectList.class.php b/wcfsetup/install/files/lib/system/tagging/TTaggedObjectList.class.php
new file mode 100644
index 0000000000..742367ae91
--- /dev/null
+++ b/wcfsetup/install/files/lib/system/tagging/TTaggedObjectList.class.php
@@ -0,0 +1,33 @@
+<?php
+namespace wcf\system\tagging;
+use wcf\util\StringUtil;
+
+/**
+ * Helper functions to query tagged objects.
+ * 
+ * @author      Alexander Ebert
+ * @copyright   2001-2020 WoltLab GmbH
+ * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @package     WoltLabSuite\Core\System\Tagging
+ */
+trait TTaggedObjectList {
+	/**
+	 * Processes the `$orderBy` parameters to inject the parameter into the `GROUP BY` parameter.
+	 * 
+	 * @param string $groupBy
+	 * @param string $orderBy
+	 * @return string
+	 */
+	protected function getGroupByFromOrderBy($groupBy, $orderBy) {
+		if (!empty($orderBy)) {
+			$orderBy = explode(',', $orderBy);
+			$orderBy = array_map(function ($order) {
+				return StringUtil::trim(preg_replace('~\s+(?:ASC|DESC)\s*$~i', '', $order));
+			}, $orderBy);
+			
+			$orderBy = ', ' . implode(', ', $orderBy);
+		}
+		
+		return "GROUP BY {$groupBy}{$orderBy}";
+	}
+}
-- 
2.20.1