Also add categories as hashtags?

[futtta]

I'm kind of old-fashioned and I use tags for non-recurring subject and categories for recurring topics on my blog. For that reason I would like ActivityPub to also use my categories as hashtags. I've been looking around (and getting kind of lost) in the source code and I found

wordpress-activitypub/includes/transformer/class-post.php

Lines 501 to 527 in 2bb66d1

	protected function get_tag() {
	if ( false !== $this->tags ) {
	return $this->tags;
	}
	$tags = parent::get_tag();
	$post_tags = \get_the_tags( $this->item->ID );
	if ( $post_tags ) {
	foreach ( $post_tags as $post_tag ) {
	// Tag can be empty.
	if ( ! $post_tag ) {
	continue;
	}
	$tags[] = array(
	'type' => 'Hashtag',
	'href' => \esc_url( \get_tag_link( $post_tag->term_id ) ),
	'name' => esc_hashtag( $post_tag->name ),
	);
	}
	}
	$this->tags = \array_unique( $tags, SORT_REGULAR );
	return $this->tags;
	}

where tags are "harvested" but I don't see a filter there which I could use to add categories.

So; any pointers on how to add categories as ActivityPub hashtags?

[pfefferle]

The general problem with categories is the naming collision. If you have a tag and a category with the same name, it is hard to reference that properly, because the concept of different taxonomies is not known in the ActivityPub world.

[futtta]

OK, but assuming there is a filter in the code I referenced, when adding categories it would be the responsibility of the one using that filter to ensure uniqueness, no? ;-)

[pfefferle]

that is true :)

the best filter would be activitypub_activity_{$class}_object_array: https://github.com/Automattic/wordpress-activitypub/blob/f1962229636805143e1cd79c060eccee8b88e69c/includes/activity/class-generic-object.php#L299C27-L299C69 (activitypub_activity_base_object_object_array)

[futtta]

I'll play around with that :)