kayser's Profile

Problem: I have 3 custom post types - Artists, Books, and Works on Paper. I have two one-to-many (O2M) relationships: Artists-Books where Artist is parent and Book is child, and Artists-Works On Paper where Artist is parent and Work on Paper is child. I'm using the Favorites plugin to allow my site visitors to add favorite Books and favorite Works on Paper. In the list of favorite posts, I would like to display information about the related Artist.

Solution: The best way to handle this is to use the Favorites plugin's filters API to filter the favorites list HTML. You can use the Toolset Post Relationships API toolset_get_related_posts to get information from related posts in that filter callback:

/**
 * Toolset Support 
 * Filter the Favorites list information to display related Artiste info
 * Currently supports Livres and Oeuvres Sur Papiers post types for Favorites
 * Extendable by adding a case statement for new post type / relationship slug
 * https://toolset.com/forums/topic/find-related-custom-post-type/
 */
  
add_filter( 'favorites/list/listing/html', 'custom_favorites_listing_html', 10, 4 );
function custom_favorites_listing_html($html, $markup_template, $post_id, $list_options)
{
  // relationship slugs per favorite post type
  $post_type = get_post_type( $post_id );
  switch($post_type) {
    case "livre":
      $rel_slug = "livre_artiste";
      break;
  
    case "oeuvre-sur-papier":
      $rel_slug = "oeuvre-sur-papier-artiste";
      break;
  
    default:
      return $html;
  };
    
  // Get related posts with Toolset post relationships API
  $children_args = [
    'query_by_role' => 'parent',
    'role_to_return' => 'child'
  ];
  $children = toolset_get_related_posts( $post_id, $rel_slug, $children_args);
    
  // Build a string of related post titles, separated by a comma, 
  // and concatenate it into response HTML, then return it
  $child_titles = [];
  if( $children && count( $children ) > 0 ) {
    foreach( $children as $child ){
      $child_titles[]= get_the_title($child);
    }
    return $html . implode(',', $child_titles);
  }
    
  // in case no related posts are found, return the default HTML
  return $html;
}