From 0143e8bcf4f42c26dee5c88429e083b44bcbf769 Mon Sep 17 00:00:00 2001
From: Jake Dallimore <jake@moodle.com>
Date: Mon, 14 Oct 2019 11:47:57 +0800
Subject: [PATCH] MDL-66796 mod_quiz: only update the id number if changed

If the idnumber is present in the DB, it's set to null. In this case,
don't update the value.
---
 question/category_class.php | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/question/category_class.php b/question/category_class.php
index 7a9bdb8086f..902276776bc 100644
--- a/question/category_class.php
+++ b/question/category_class.php
@@ -437,6 +437,7 @@ class question_category_object {
         $cat->sortorder = 999;
         $cat->stamp = make_unique_id_code();
         $cat->idnumber = $idnumber;
+
         $categoryid = $DB->insert_record("question_categories", $cat);
 
         // Log the creation of this category.
@@ -491,6 +492,7 @@ class question_category_object {
             }
         }
 
+        $updateidnumber = true;
         if ((string) $idnumber === '') {
             $idnumber = null;
         } else if (!empty($tocontextid)) {
@@ -498,6 +500,7 @@ class question_category_object {
             if ($DB->record_exists('question_categories',
                     ['idnumber' => $idnumber, 'contextid' => $tocontextid])) {
                 $idnumber = null;
+                $updateidnumber = false;
             }
         }
 
@@ -509,7 +512,9 @@ class question_category_object {
         $cat->infoformat = $newinfoformat;
         $cat->parent = $parentid;
         $cat->contextid = $tocontextid;
-        $cat->idnumber = $idnumber;
+        if ($updateidnumber) {
+            $cat->idnumber = $idnumber;
+        }
         if ($newstamprequired) {
             $cat->stamp = make_unique_id_code();
         }