Node preview button generates useless menu link

We experienced the same issue.
When going to add a new page, then clicking on the “Provide a menu link”.
Then pressing “Preview”, a temporary menu link gets generated.
And when leaving the new page, because you decide you don’t need it, that temporary menu link remains and shows up on the menu.

This is an issue because now we have broken links showing up on the menu.

Tested on:
Drupal 8.2.3
Token 1.0.0-beta2

Hi,

The bug is on line 778 of token.module, the system is not looking for the flag $node->in_preview. Unfortunately following further investigation the flag is not set on the node, this will need further investigation.

So the fix will be to add a check like :

if ($node->isNew() && empty($node->in_preview)) {

While the in_preview flag is not yet available, we can check the triggering element in $form_state. I'm not certain that checking the generated ID of the element is the best way to go, and I'm sure that this change needs some tests, but here's a patch that fixes the issue until there's a better solution.

Hi mbrc, Thanks! for the patch this really solved my issue.

Entity builders are called before submit buttons, and in_preview is set there.

Wondering if we should instead add this as a submit callback, especially after #2068063: Change "Save and keep un-/published" buttons to a "Published" checkbox and an included "Save" button is in. Because every ajax callback also calls this I think.

Tests would be great as well.

#4 worked for us. Thank you!

If anyone reads this and doesn't know how to use the patch, let me share a sanitized version of our deployment instructions:

1. login to my-server
2. su to my-admin-user
3. cd to /tmp
4. download patch

curl https://www.drupal.org/files/issues/token_node_preview_menu_link-2823731-4.patch --output token_node_preview_menu_link-2823731-4.patch
    

5. cd to token folder

cd /var/www/html/examplecom/modules/token

6. backup token.module

cp token.module /tmp/token.module.pre-patch

7. put site into maintenance mode
8. patch the files

patch -p1 < /tmp/token_node_preview_menu_link-2823731-4.patch
Sample output:

patching file token.module
Hunk #1 succeeded at 743 with fuzz 2 (offset 4 lines).
    

9. sanity-check diff

diff /tmp/token.module.pre-patch token.module
Sample output:

745a746,749
>           // Don't create a menu link if the node is being previewed.
>           if ($form_state->getTriggeringElement()['#id'] == 'edit-preview') {
>             return;
>           }
    

10. flush drupal caches

https://example.com/admin/config/development/performance

11. test
    1. start a new article
    2. Menu Settings -> [x] provide a menu link
    3. URL Alias -> [x] Generate automatic URL alias
    4. click "preview"
    5. return to article
    6. save article
    7. confirm there is only ONE entry in the menu sidebar
12. take site out of maintenance mode

Patch was failing to apply with composer rerolled with latest dev.

I had the same problem.
I can confirm that the patch #8 solved it.

Patch #8 works for me. I extended the patch with a test to cover this scenario.

I can confirm that patch #11 works for me and solves the issue for me. There is no menu link created in Preview mode when the node hasn't been saved yet.

Thanks for the test. Made some coding standard and deprecation fixes:

diff --git a/tests/src/Functional/TokenMenuTest.php b/tests/src/Functional/TokenMenuTest.php
index 8768207..134d51a 100644
--- a/tests/src/Functional/TokenMenuTest.php
+++ b/tests/src/Functional/TokenMenuTest.php
@@ -457,9 +457,9 @@ class TokenMenuTest extends TokenTestBase {
   }
 
   /**
-   * Test that no menu link is generated when the node gets previewed.
+   * Tests that no menu link is generated when the node gets previewed.
    */
-  public function testPreviewMenuLink(){
+  public function testPreviewMenuLink() {
     $this->drupalCreateContentType(['type' => 'article']);
     $permissions = [
       'access administration pages',
@@ -476,8 +476,9 @@ class TokenMenuTest extends TokenTestBase {
       'menu[enabled]' => TRUE,
       'menu[title]' => 'English menu title',
     ];
-    $this->drupalPostForm('/node/add/article', $edit, t('Preview'));
-    $menu_links = \Drupal::entityManager()->getStorage('menu_link_content')->loadByProperties(['menu_name' => 'main']);
+    $this->drupalGet('node/add/article');
+    $this->submitForm($edit, t('Preview'));
+    $menu_links = \Drupal::entityTypeManager()->getStorage('menu_link_content')->loadByProperties(['menu_name' => 'main']);
     $this->assertEmpty($menu_links);
   }