Entity(s) causing path suffix conflicts are not indicated

[westonruter]

Feature description

In a couple cases recently users have reported the inability to select the Legacy Reader or Path Suffix paired URL structures and getting this notice:

There is a post, term, user, or some other entity that is already using the “amp” URL slug. For this reason, you cannot currently use the path suffix or legacy reader paired URL structures.

• https://wordpress.org/support/topic/my-amp-urls-return-a-blank-screen-when-i-click-on-google-serps-mobile/#post-14498701
• https://wordpress.org/support/topic/500-xxx-error-paired-url-structure-featured-images-not-showing/

We don't expose the conflict in the UI at present.

For example, if I add this plugin code:

add_action('init', function () {
	register_taxonomy( 'amp', 'post' );
});

The settings screen shows:

The conflict is not shown, but the conflicts are returned in the API response.

In the console doing:

(await wp.apiFetch({path:'/amp/v1/options'})).endpoint_path_slug_conflicts

Results in:

So we just need to amend the notice with a list of what the conflicts are. This can be done in an unordered list.

The REST API endpoint should return the taxonomy slug, taxonomy translated name, and term edit link for each entity if available. When an option says “unavailable due to slug conflict” there should be a clear reference to the above notice.

amp-wp/src/PairedRouting.php

Lines 337 to 390 in 3bb15f3

	public function get_endpoint_path_slug_conflicts() {
	$conflicts = [];
	$amp_slug = amp_get_slug();
	$post_query = new WP_Query(
	[
	'post_type' => 'any',
	'name' => $amp_slug,
	'fields' => 'ids',
	'posts_per_page' => 100,
	]
	);
	if ( $post_query->post_count > 0 ) {
	$conflicts['posts'] = $post_query->posts;
	}
	$term_query = new WP_Term_Query(
	[
	'slug' => $amp_slug,
	'fields' => 'ids',
	'hide_empty' => false,
	]
	);
	if ( $term_query->terms ) {
	$conflicts['terms'] = $term_query->terms;
	}
	$user = get_user_by( 'slug', $amp_slug );
	if ( $user ) {
	$conflicts['users'] = [ $user->ID ];
	}
	foreach ( get_post_types( [], 'objects' ) as $post_type ) {
	if (
	$amp_slug === $post_type->query_var
	||
	isset( $post_type->rewrite['slug'] ) && $post_type->rewrite['slug'] === $amp_slug
	) {
	$conflicts['post_types'][] = $post_type->name;
	}
	}
	foreach ( get_taxonomies( [], 'objects' ) as $taxonomy ) {
	if (
	$amp_slug === $taxonomy->query_var
	||
	isset( $taxonomy->rewrite['slug'] ) && $taxonomy->rewrite['slug'] === $amp_slug
	) {
	$conflicts['taxonomies'][] = $taxonomy->name;
	}
	}
	return $conflicts;
	}

Also, I just realized that we should also check if the amp_get_slug() exists among WP_Rewrite::$endpoints and indicate that as another conflict.

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Acceptance criteria

Implementation brief

QA testing instructions

Demo

Changelog entry

[westonruter]

QA Passed

I created a post, page, category, tag, and user all with the amp slug. I also registered a taxonomy and a post type with the amp slug. And I also registered an amp rewrite endpoint. I then got the message as expected, without the ability to select path suffix or legacy Reader structures: