Modifying ActivityPub posts via Wordpress filter?

[craigconstantine]

I noticed that to_array() in https://github.com/pfefferle/wordpress-activitypub/blob/44c652eba8174368c9fdc2ca33e02fd2afbe436d/includes/model/class-post.php#L43 provides for filters for activitypub_post. But when I tried to hook the following, it didn't have an effect.

So my first question is: Is this the right place to try hooking?

I understand these are some ugly preg_replace()'s. It's just copy-n-paste from another filter I've tuned for use on my RSS feed posts.

// custom munging of posts going out via ActivityPub
add_filter( 'activitypub_post', 'craig_activitypub_post_filter' );
function craig_activitypub_post_filter( $post /* an ActivityPub array, not a WP Post object */ ) {

	// inline minimal styling for blockquotes
	$post['content'] = preg_replace(
		'/<blockquote/i',
		'<blockquote style="margin-left: 20px; border-left: 2px solid #f2777a; padding-left: 10px;" ',
		$post['content']
	);

	// remove slip address gutenburg blocks
	$post['content'] = preg_replace(
		'/<div class="wp-block-gutenberg-sladdr-block-address slip-address">\s*<p>[^<]*<\/p>\s*<\/div>/i',
		'',
		$post['content']
	);

	// WP generates CITE tags for the citation portion of a blockquote. This doesn't
	// work well with email clients and RSS readers and such. We turn them back
	// in P tags, add italics and try some opacity via embedded styling.
	$post['content'] = preg_replace( '/<cite>/i', '<p><i>', $post['content'] );
	$post['content'] = preg_replace( '/<\/cite>/i', '</i></p>', $post['content'] );

	return $post;
}

[pfefferle]

It is/should be the right place (let me know if you need some more Parameters for the filter!). To check if your changes are working you can add /activitypub at the end of each post, to see the result. Otherwise it is hard to check, because mastodon and others might strip html elements.

Btw. Here is an example https://notiz.blog/2022/11/14/the-at-protocol/activitypub/

[craigconstantine]

Terrific. The /activitypub tip made it easy to troubleshoot. Thanks.