Notice: Undefined index: item_spacing in /var/www/html/wordpress/wp-includes/class-walker-page.php on line 106

[jrswgtr]

I get this notice while trying to generate a sitemap with the page walker.

Notice: Undefined index: item_spacing in /var/www/html/wordpress/wp-includes/class-walker-page.php on line 106

[SergeyBiryukov]

Introduced in [38523].

[ketuchetan]

Actually, I am no able to reproduce this issue. @jrswgtr please provide me the steps to reproduce the issue.

[bhargavbhandari90]

Thanks @jrswgtr for reporting this.
I am able to replicate these notice on four lines at 106, 56, 199 and 81.

[bhargavbhandari90]

@ketuchetan Try by adding this code into your functions.php. Make sure you have made Debugging True from your wp-config.php. You can also check by any debugging plugin.

function test_page_walker() {
	$walker_page = new Walker_Page();
	echo '<ul>'.$walker_page->walk(get_pages(), 0).'</ul>'; // 0 means display all levels.	
}
add_action( 'init', 'test_page_walker' );

[ketuchetan]

Added patch from the src directory

[bhargavbhandari90]

Hi, @ketuchetan

I saw that your patch is duplicate. Can you explain why? :-) I think you should have a better solution than the previous patch. :-)

[ketuchetan]

@bhargavbhandari90 There is no any changes but you can see my patch I have created patch from the /src/ directory of development repository.

[peterwilsoncc]

Replying to ketuchetan:

@bhargavbhandari90 There is no any changes but you can see my patch I have created patch from the /src/ directory of development repository.

Thanks, I appreciate the effort. The grunt patch command is really good at picking up sub-directories and will prompt if needs be. While helpful, refreshes like these are unnecessary.

[peterwilsoncc]

In 39949:

Menus: Prevent notice thrown in class-walker-page.php.

Calling Walker_Page::walk() directly was causing an Undefined index: item_spacing notice to be thrown, this adds an isset() check to prevent it.

Props bhargavbhandari90.
Fixes #39564.

[peterwilsoncc]

Reopening for backporting to 4.7 branch.

[bhargavbhandari90]

Replying to peterwilsoncc:

In 39949:

Menus: Prevent notice thrown in class-walker-page.php.

Calling Walker_Page::walk() directly was causing an Undefined index: item_spacing notice to be thrown, this adds an isset() check to prevent it.

Props bhargavbhandari90.
Fixes #39564.

Thank you @peterwilsoncc

[dd32]

@peterwilsoncc in [39949] I note that the logic has now changed from the 4.6 behaviour in the event that the item_spacing arg is not provided - it'll default to discard in that case now.

Should this have been if ( ! isset(...) || 'preserve' ...?

[ketuchetan]

Changed the condition based on the @dd32 suggestion.

[peterwilsoncc]

Replying to dd32:

@peterwilsoncc in [39949] I note that the logic has now changed from the 4.6 behaviour in the event that the item_spacing arg is not provided - it'll default to discard in that case now.

Should this have been if ( ! isset(...) || 'preserve' ...?

That's a good catch.

It looks like the behaviour has changed when the walker is called directly rather than via wp_list_pages() and related functions. I'm inclined to leave it as it's an edge case and, arguably, ill advised.

[dd32]

It looks like the behaviour has changed when the walker is called directly rather than via wp_list_pages() and related functions. I'm inclined to leave it as it's an edge case and, arguably, ill advised.

I'm inclined to agree, the only thing that I can think of is the case where you've extended the Walker with a custom class. However, in that case you should still be using wp_list_pages() and passing the walker arg.
I'm fine with leaving this as-is then.

[dd32]

In 40092:

Menus: Prevent notice thrown in class-walker-page.php.

Calling Walker_Page::walk() directly was causing an Undefined index: item_spacing notice to be thrown, this adds an isset() check to prevent it.

Props bhargavbhandari90, peterwilsoncc.
Merges [39949] to the 4.7 branch.
Fixes #39564.