I’m trying to get a default featured image to display using a filter of “post_thumbnail_id” in my child theme’s functions.php file. I’m able to add a default thumbnail for post_type of topic, but I’d like it to be a custom thumbnail based on the id, or name of the forum the topic is in. Here’s what I have so far:

function my_filter_thumbnail_id( $thumbnail_id, $post = null ) {
	if ( $post->post_type != 'topic' )
		return $thumbnail_id;
	
	$forumname = get_forum_name( $post->forum_id );
	if ( $forumname == "wellness")
		$thumbnail_id = 7091;

	return  $thumbnail_id;
}
add_filter( 'post_thumbnail_id', 'my_filter_thumbnail_id', 20, 5 );

The issue is, “get_forum_name(),” is an undefined function. I’m not looking to override the default functions of bbPress, just be able to access the forum_id or forum_name from my theme’s functions.php file. Any help would be greatly appreciated! Thanks

[@robin-w Moderator 1 year, 4 months ago]

$forumname = bbp_get_forum_title( $post->forum_id );

[@ttiefenbach Participant 1 year, 4 months ago]

Thanks for the quick reply! Unfortunately, your code returned the topic’s title.

That allowed me to narrow my search, though, and I was able to get the correct functions for my permalink structure:

function my_filter_thumbnail_id( $thumbnail_id, $post = null ) {
	if ( $post->post_type != 'topic' )
		return $thumbnail_id;
	
	$forumid = bbp_get_topic_forum_id();
	if ( $forumid == 6728 )
		$thumbnail_id = 7091;

	return  $thumbnail_id;
}
add_filter( 'post_thumbnail_id', 'my_filter_thumbnail_id', 20, 5 );

I could probably use the bbp_get_forum_title() function to get the tiel to compare, like you suggested, but I went with just validating the ID since it was working.

Thanks for your help!!