From b71063cf23dece6cb054f681942b409cbf8ab7e7 Mon Sep 17 00:00:00 2001
From: mcdruid <drew@mcdruid.co.uk>
Date: Tue, 23 May 2023 18:30:16 +0100
Subject: [PATCH] Issue #1621334 by SebCorbin, poker10, szt, larowlan, swentel,
 salvis: Notice: Undefined property: stdClass::$forum_tid in forum_node_view()

---
 modules/forum/forum.module |  2 +-
 modules/forum/forum.test   | 40 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/modules/forum/forum.module b/modules/forum/forum.module
index 0baddd4ee249..458ca43b6dc9 100644
--- a/modules/forum/forum.module
+++ b/modules/forum/forum.module
@@ -263,7 +263,7 @@ function _forum_node_check_node_type($node) {
  * Implements hook_node_view().
  */
 function forum_node_view($node, $view_mode) {
-  if (_forum_node_check_node_type($node)) {
+  if (!empty($node->forum_tid) && _forum_node_check_node_type($node)) {
     if ($view_mode == 'full' && node_is_page($node)) {
       $vid = variable_get('forum_nav_vocabulary', 0);
       $vocabulary = taxonomy_vocabulary_load($vid);
diff --git a/modules/forum/forum.test b/modules/forum/forum.test
index 0a5989fa44bf..a6f9eb182f11 100644
--- a/modules/forum/forum.test
+++ b/modules/forum/forum.test
@@ -210,6 +210,46 @@ class ForumTestCase extends DrupalWebTestCase {
     $node->uid = 1;
     $node->taxonomy_forums[LANGUAGE_NONE][0]['tid'] = $this->root_forum['tid'];
     node_save($node);
+
+    // Verify that adding taxonomy_forums reference field to another content
+    // type does not trigger any errors.
+    // Create new content type.
+    $type_name = 'test_' . strtolower($this->randomName());
+    $type = $this->drupalCreateContentType(array('name' => $type_name, 'type' => $type_name));
+    // Create field instance on the bundle.
+    $vocabulary = taxonomy_vocabulary_load(variable_get('forum_nav_vocabulary', 0));
+    $instance = array(
+      'field_name' => 'taxonomy_forums',
+      'entity_type' => 'node',
+      'label' => $vocabulary->name,
+      'bundle' => $type->type,
+      'required' => FALSE,
+      'widget' => array(
+        'type' => 'options_select',
+      ),
+      'display' => array(
+        'default' => array(
+          'type' => 'taxonomy_term_reference_link',
+          'weight' => 10,
+        ),
+        'teaser' => array(
+          'type' => 'taxonomy_term_reference_link',
+          'weight' => 10,
+        ),
+      ),
+    );
+    field_create_instance($instance);
+    // Create node and access node detail page.
+    $settings = array(
+      'type' => $type->type,
+      'title' => $type_name,
+      'taxonomy_forums' => array(LANGUAGE_NONE => array()),
+    );
+    $node1 = $this->drupalCreateNode($settings);
+    $this->drupalGet('node/' . $node1->nid);
+    $this->assertResponse(200);
+    // Remove the field instance.
+    field_delete_instance($instance);
   }
 
   /**