Infinite refresh loop in Customizer when using the filter 'theme_mod_nav_menu_locations'

[Chouby]

In a multilingual plugin, we need to filter the navigation menu outputted by the theme.

In Polylang, I am thus using the filter theme_mod_nav_menu_locations to populate the theme locations with the nav menus in the correct language.

Recent changes made to the customizer in WP 4.7 beta1 seem to introduce a backward compatibility issue as using this filter is now causing an infinite refresh loop in the customizer.

Here is a snippet to reproduce:

if ( ! is_admin() ) {
	add_filter( 'theme_mod_nav_menu_locations', 'pll_theme_mod_nav_menu_locations' );
}

function pll_theme_mod_nav_menu_locations( $menus ) {
	if ( is_array( $menus ) ) {
		foreach ( $menus as $loc => $menu ) {
			$menus[ $loc ] = 19; // some existing menu_id
		}
	}
	return $menus;
}

[westonruter]

@Chouby This issue wasn't present in WordPress 4.6.1?

Relates to #37032.

[Chouby]

It indeed works in previous versions of WordPress.

I did not see #37032 before, but I see now that it was opened for WP 4.5 whereas I had no issue with this version.

[westonruter]

@Chouby ok, I think it may be something to do with the changes done for #27403, but I'm having a hard time pinpointing it. In any case, for an immediate fix while waiting on #37032, I suggest that you modify your code as follows:

<?php
function pll_remove_theme_mod_nav_menu_locations_filter() {
        remove_filter( 'theme_mod_nav_menu_locations', 'pll_theme_mod_nav_menu_locations' );
}
if ( ! is_admin() ) {
        add_filter( 'theme_mod_nav_menu_locations', 'pll_theme_mod_nav_menu_locations' );

        // Note that WP_Customize_Manager::customize_preview_settings() is called at wp_footer priority 10.
        add_action( 'wp_footer', 'pll_remove_theme_mod_nav_menu_locations_filter' );
}

The problem I think is that your filter is interfering with the customizer filters added for nav menus. So it is important to remove your filter before the customizer prints out the setting values so that it doesn't get stuck in that infinite loop.

Try that and let me know how you go.

[westonruter]

Duplicate of #37032.

A fix for the underlying issue has been committed in [39112].

[Chouby]

Fantastic! I just tested the revision 39117 and it works as expected now.
Thanks!

[SpencerFinnell]

If anyone else is having this issue the same conflict exists with the latest versions of:

​https://wordpress.org/plugins/nav-menu-roles/
​https://wordpress.org/plugins/menu-items-visibility-control/

However

​https://wordpress.org/plugins/if-menu/

Seems to work.

[westonruter]

@SpencerFinnell I can indeed reproduce issue in the Nav Menu Roles plugin:

0. Given Twenty Seventeen activated with starter content imported
1. Go to the nav menus admin page
2. Set each of the social nav menu's items to only display if user is not logged in.
3. Open customizer.
4. Infinite refresh ensues.

[westonruter]

@SpencerFinnell would you give 38612.0.diff​ a try?

[SpencerFinnell]

Yep, the patch fixes the issue for me.

[westonruter]

In 39510:

Customize: Prevent infinite full refresh from occurring when selective refresh falls back for a nav menu that has items excluded from rendering via filtering.

See #37032.
Fixes #38612.

[westonruter]

In 39511:

Customize: Prevent infinite full refresh from occurring when selective refresh falls back for a nav menu that has items excluded from rendering via filtering.

Merges [39510] onto 4.7 branch.
Fixes #38612 for 4.7.