ludalex

change get_topic_ID() in class.ipbcomments.php with this:

function get_topic_ID () {

		$post_ID = get_the_ID();
		$meta = get_post_meta($post_ID,'forum_topic_meta');

		if(!empty($meta)) {
			extract($meta[0]);
			return $topic_id;
		} else {
			return false;
		}

	}

and in comments.php or whatever you want:

$ipb_comments = new WP_IPBComments;
	echo "wp post: ". get_the_ID() . "<br>";
	$topicID = $ipb_comments->get_topic_ID();
	if($topicID) {

		echo "topic id:". $topicID;
		echo "replies number: ". $ipb_comments->get_replies_number($topicID);

	}
	else {
			echo "Forum post doesn't exist.";
	}

golgoth, have you checked if the posts that give you the error got posted on the forum using IPB.Comments?
That could be the problem.

I did it my myself:
add these two functions to class.ipbcomments.php:

function get_replies_number( $topic_id ) {

		if ( ! (isset($this->options['ipb_field_path']) OR file_exists($this->options['ipb_field_path'])) ) {
			return FALSE;
		}

		ini_set( 'display_errors', 0 );

		// Keep the board from redirecting
		// https://community.invisionpower.com/tracker/issue-26224-issues-with-ssiphp/
		define('CCS_GATEWAY_CALLED',FALSE);

		require_once( $this->options['ipb_field_path'] .'/initdata.php' );

		require_once( IPS_ROOT_PATH .'sources/base/ipsController.php' );
		require_once( IPS_ROOT_PATH .'sources/base/ipsRegistry.php' );

		$registry = ipsRegistry::instance();
		$registry->init();

		// build the select statement, skip the original post, we just want the replies
		$registry->DB()->build( array( 'select' => 'posts',
							'from'  => 'topics',
							'where' => 'tid = ' . $topic_id
							)
						);

		$result = $registry->DB()->execute();

		 if ( $result ) {

				$num = $registry->DB()->fetch();

				return $num['posts'];	

				}

	}

and:

function get_topic_ID () {

		$post_ID = get_the_ID();
		$meta = get_post_meta($post_ID,'forum_topic_meta');
		extract($meta[0]);

		return $topic_id;

	}

And anywhere on your wordpress page, for example in comments.php, you can display how many replies has the topic corresponding to the post with this:

$ipb_comments = new WP_IPBComments;
	echo "topic id: ".$topicID = $ipb_comments->get_topic_ID();
	echo "replies number: ". $ipb_comments->get_replies_number($topicID);

Shouldn’t this be really easy with the XML-RPC Api?

Anyway, any updates?