[wp-trac] [WordPress Trac] #32344: Menu items in large menus disappear unexpectedly in wp-admin/nav-menus.php on most default server configurations

[WordPress Trac]

#32344: Menu items in large menus disappear unexpectedly in wp-admin/nav-menus.php
on most default server configurations
----------------------------+-----------------------------
 Reporter:  Zuige           |      Owner:
     Type:  defect (bug)    |     Status:  new
 Priority:  normal          |  Milestone:  Awaiting Review
Component:  General         |    Version:  trunk
 Severity:  normal          |   Keywords:
  Focuses:  administration  |
----------------------------+-----------------------------
 == Issue ==

 Due to the way nav-menus.php handles a save action, the maximum number of
 menu items in a single WordPress navigation menu is limited to 83 on
 default php.ini settings on most modern server configurations.

 The ini setting that affects this behaviour is max_input_vars. The default
 value on many configurations I've tested is 1000.



 == Steps to reproduce ==

 '''1. Create a new menu'''

 Done here with wp-cli:

 {{{
 wp menu create "Big Menu"
 }}}

 '''2. Manually add 100 custom menu items.'''

 As shown here with wp-cli:

 {{{
 for i in {1..100}; do wp menu item add-custom 3 item-$i "#"; done
 }}}

 '''3. Navigate to wp-admin/nav-menus.php and load up the edit menu
 screen.'''

 '''4. Hit "Save Menu" and Boom; only 83 menu items remain, depending on
 your max_input_vars value.'''



 == Remediation ==

 '''UX improvement:''' We should warn the user if the number of the
 resulting POST data entries exceeds the local max_input_vars value before
 submitting the "Save Menu" action.

 There's a plugin by Sevenspark that warns if the menu size is near the
 limit: [https://github.com/sevenspark/menu-limit-detector]

 or

 '''Actual fix:''' We should pre-process the submit data from ''input
 ['menu-item-*']'' form fields on the browser side to raise the upper limit
 to something less likely to be reached.

 One solution would be to just store the ''input['menu-item-*']'' fields in
 a single POST item.

 Alternatively, we could serialise the fields from each menu item in its
 own key, which would raise the limit to somewhere close to 1000 items /
 menu.

 I'm working on a patch for this right now. Comments?



 == Related issues ==

 #32009
 #14684
 #14134

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Ticket URL: <https://core.trac.wordpress.org/ticket/32344>
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