Removing all Media attached to a deleted revision

I wrote a cron job to delete revisions for posts older than 4 weeks, and then remove any unattached media.

// delete old revisions
	global $wpdb;
	$num1 = $wpdb->query("DELETE FROM ".$wpdb->posts." WHERE post_type = 'revision'");
	// clean orphaned post meta.
	$num2 = $wpdb->query("DELETE pm FROM ".$wpdb->postmeta." pm LEFT JOIN ".$wpdb->posts." p ON pm.post_id = p.ID WHERE p.ID IS NULL");
	// delete unattached attachments (images & videos not referenced in any posts)
	$attachments = get_posts([
		"post_type" => "attachment",
		"numberposts" => -1,
		"post_parent" => 0,
		"fields" => "ids",
	]);
	foreach ($attachments as $id) {
		wp_delete_attachment($id, true);
	}

But unfortunately, attachments that only exist in a revision remain but really have no reference in the post content.

The attachments still retain a parent_post value of the published post, and there is no apparently easy way to detect if the attachment is contained within the post.

So now I have a load of attachements relating to posts which actually do not reference them in the content.

How do I know which ones are actually referenced in the post besides parsing the content?
I’m 99% sure of the answer but just want to check that there isn’t a better solution.

• This topic was modified 3 years, 8 months ago by hedgehog90.