From 7c79dab1970770fc69deabb17ac108c82e7d6f3b Mon Sep 17 00:00:00 2001
From: Jan-Hendrik Willms <tleilax+studip@gmail.com>
Date: Tue, 23 Sep 2025 11:21:22 +0200
Subject: set parent_id to null when deleting wiki pages and add migration that
 fixes invalid entries, fixes #5832

Closes #5832

Merge request studip/studip!4447
---
 db/migrations/5.5.35_cleanup_wiki_page_parent_id.php | 18 ++++++++++++++++++
 lib/models/WikiPage.php                              | 10 +++++++---
 2 files changed, 25 insertions(+), 3 deletions(-)
 create mode 100644 db/migrations/5.5.35_cleanup_wiki_page_parent_id.php

diff --git a/db/migrations/5.5.35_cleanup_wiki_page_parent_id.php b/db/migrations/5.5.35_cleanup_wiki_page_parent_id.php
new file mode 100644
index 0000000..a374429
--- /dev/null
+++ b/db/migrations/5.5.35_cleanup_wiki_page_parent_id.php
@@ -0,0 +1,18 @@
+<?php
+final class CleanupWikiPageParentId extends Migration
+{
+    public function description()
+    {
+        return 'Remove invalid parent_id from wiki_pages';
+    }
+
+    protected function up()
+    {
+        $query = "UPDATE `wiki_pages` AS w0
+                  LEFT JOIN `wiki_pages` AS w1
+                    ON (w0.`parent_id` = w1.`page_id`)
+                  SET w0.`parent_id` = NULL
+                  WHERE w1.`page_id` IS NULL";
+        DBManager::get()->execute($query);
+    }
+}
diff --git a/lib/models/WikiPage.php b/lib/models/WikiPage.php
index b8982d8..57d9899 100644
--- a/lib/models/WikiPage.php
+++ b/lib/models/WikiPage.php
@@ -24,8 +24,8 @@
  * @property string|null $locked_by_user_id database column
  * @property int $chdate database column
  * @property int $mkdate database column
- * @property SimpleORMapCollection<WikiVersion> $versions 
- * @property SimpleORMapCollection<WikiOnlineEditingUser> $onlineeditingusers 
+ * @property SimpleORMapCollection<WikiVersion> $versions
+ * @property SimpleORMapCollection<WikiOnlineEditingUser> $onlineeditingusers
  * @property User $user belongs_to User
  * @property Course $course belongs_to Course
  * @property-read (WikiPage | null) $parent additional field
@@ -88,12 +88,16 @@ class WikiPage extends SimpleORMap implements PrivacyObject
         ];
 
         $config['registered_callbacks']['before_store'][] = 'createVersion';
+        $config['registered_callbacks']['after_delete'][] = function (WikiPage $page) {
+            $query = "UPDATE `wiki_pages` SET `parent_id` = NULL WHERE `parent_id` = ?";
+            DBManager::get()->execute($query, [$page->id]);
+        };
+
         $config['default_values']['last_author'] = 'nobody';
 
         parent::configure($config);
     }
 
-
     protected function createVersion()
     {
         $last_version = $this->versions[0];
-- 
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