How to set up a has_many :through association with Ultrasphinx

I'm using the Ultrasphinx plugin with Sphinx to add search to my app,
but I'm having a tough time figuring out how to index a
has_many :through relationship. Say, for example, I'm looking at a
relationship like this:

Playlist has_many songs :through => 'playlistings'

I want to be able to do a song-based search that will return the
Playlists that have those songs. I know I need to use
the :association_sql key to set up the has_many :through join, but my
SQL sauce is weak. Here's what I have right now, which works only for
the first song:

    is_indexed :fields => [{:field => 'name', :as =>
              :include => [{:association_name => "songs", :field =>
                                 :association_sql => "JOIN
(playlistings, songs) ON ( AND"}]

Unfortunately, like I said, if I do a search by song name, Ultrasphinx
only matches playlists if I search for the first song in a playlist...
searching by all other song names (e.g., the name of the second or
third song in a playlist) returns nothing. Any ideas?

Thanks so much for any help!

Hey everyone, got it to work! Here's what I'm using:

  is_indexed :fields => [{:field => 'name', :as => 'playlist_name'}],
      :concatenate => [{ :class_name => 'Song', :field => 'name',
                      :association_sql => "LEFT JOIN playlistings ON
(( LEFT JOIN songs ON
(", :as => 'song' }]

Hopefully that'll help someone out sometime. :slight_smile:

Thanx for your information. Wasting half a day I found your post and
this help me so much.

Thanx a lot :slight_smile: