search for: comments_text

I have a Topic that has_many comments. In the search results only want Topics to show up, but I want them to include the text of the comments that they have when they are indexed. To do this I''ve added a :comments_text field for acts_as_ferret and the comments_text method gathers the text from all comments up into a string that can be indexed. The trick is that when comments are added, updated, or deleted the Topic needs to be updated in the ferret index, and I''m not sure what the best way to enforce th...