allow arbitrary HTML attributes on <a> produced by Walker_Category

[pbiron]

Walker_Nav_Menu currently allows arbitrary HTML attributes to be added to the <a> tags it generates via the nav_menu_link_attributes filter.

It would be useful to do the same in Walker_Category (i.e., add a category_menu_link_attributes filter).

Related: #40359

[pbiron]

To the best of my knowledge, in core Walker_Category is only used by wp_list_categories() and wp_list_categories() is only used by `WP_Widget_Categories'.

As a result, I'm not sure that the name of new filter introduced in my patch (category_menu_link_attributes) is appropriate. I named it that to mirror the new filter introduced in #40359...which was named after the existing filter in Walker_Nav_Menu.

I'd like some feedback on the naming (and inline docs) for this new filter.

[pbiron]

Another thing I noticed while putting together this patch is that there is a difference in the way wp_list_categories() and wp_list_pages() invoke Walker::walk() (via walk_category_tree() and walk_page_tree(), respectively).

Namely, wp_list_pages() passes the current page as a param to walk_page_tree(), whereas wp_list_categories() does not pass the current category as a param to walk_category_tree(), passing it instead $r['current_category'].

As a result, those hooking into the new filter proposed here need to write their funcs slightly different than the similar filters for nav_menu_link_attributes and page_menu_link_attributes, as in:

add_filter( 'category_menu_link_attributes', 'add_aria_current_category', 10, 5 );

function
add_aria_current_category( $atts, $category, $depth, $args, $id )
{
	if ( $category->term_id === $id ||
			( isset( $args['current_category'] ) &&
			$category->term_id === $args['current_category'] ) ) {
		$atts['aria-current'] = 'page' ;
		}

	return $atts ;
}

I think it might make sense to include a note about this different in the inline docs (resulting in the note appearing in DevHub. Alternatively, the note could be added a "comment" on the DevHub page for the new filter. I'd like feedback on this as well.

[afercia]

@SergeyBiryukov since you already owned #40359 would you like to own this too? :)

[afercia]

Discussed during today's accessibility bug-scrub an agreed we'd like to propose this for 4.9.9 consideration. /Cc @SergeyBiryukov

[pbiron]

Replying to afercia:

Discussed during today's accessibility bug-scrub an agreed we'd like to propose this for 4.9.9 consideration. /Cc @SergeyBiryukov

Great, thanx!

Let me know if there are any changes necessary to the patch (such as the filter name, as suggested in comment:1).

[desrosj]

Going to punt this to 5.1. It is outside of the scope for 5.0.3 (block
editor bugs, regressions, and major bugs). The patch still applies cleanly for me. Whoever ends up reviewing and committing this will just need to change the @since tag.

[audrasjb]

Patch refreshed against trunk and @since tag refreshed as well

[afercia]

40666.3.diff​ makes phpcs happy and boyscouts a missing translators comment.

[pbiron]

Thanx for the updates!

Before this gets committed, does anyone have a reaction to the question I asked in https://core.trac.wordpress.org/ticket/40666#comment:1 re: the name of the filter?

[SergeyBiryukov]

Replying to pbiron:

To the best of my knowledge, in core Walker_Category is only used by wp_list_categories() and wp_list_categories() is only used by WP_Widget_Categories.

As a result, I'm not sure that the name of new filter introduced in my patch (category_menu_link_attributes) is appropriate. I named it that to mirror the new filter introduced in #40359...which was named after the existing filter in Walker_Nav_Menu.

I'd like some feedback on the naming (and inline docs) for this new filter.

In hindsight, page_menu_link_attributes could probably have been called page_list_link_attributes, as Walker_Page is only used directly in wp_list_pages(), via walk_page_tree().

However, wp_list_pages() is also used in wp_page_menu(), so page_menu_link_attributes seemed to make sense in that regard.

For categories, I think category_list_link_attributes would make sense without deviating too much from the existing naming of page_menu_link_attributes and nav_menu_link_attributes.

[SergeyBiryukov]

In 44957:

Accessibility: Introduce category_list_link_attributes filter in Walker_Category::start_el() for the HTML attributes applied to a category list item's anchor element.

This complements the page_menu_link_attributes filter in Walker_Page::start_el() and the nav_menu_link_attributes filter in Walker_Nav_Menu::start_el().

Props pbiron, audrasjb, afercia.
Fixes #40666. See #40359.

[SergeyBiryukov]

In 44958:

Menus: Use esc_url() for the href value of page link attributes in Walker_Page::start_el(), for consistency with Walker_Nav_Menu and Walker_Category.

See #40666, #40359.

[desrosj]

Dev note: ​https://make.wordpress.org/core/2019/04/24/miscellaneous-developer-updates-in-5-2/