tobiWP

Take this solution inside a custom controller:

$query = array(
            'post_type' => 'objekt',
            'include' => 'title,author'
        );

        /*
         * WORKAROUND by nerevo
         */
        if ($query['include']) {
            $json_api->response->include_values = array_merge($json_api->response->include_values, explode(',', $query['include']));
        }

        $posts = $json_api->introspector->get_posts($query);