Rails, Sphinx (thinking_sphinx) and sorting from associations

I have 3 models:

Stats (belongs_to :item)

  t.integer :skin_i开发者_Python百科d
  t.integer :item_id
  t.integer :rating

Item (has_many :stats)

and

Skin (has_many :stats)

Using thinking_sphinx i want to create a separate index, for items, sorted by :rating for particular :skin_id

So, i'm trying to:

  define_index 'sort_by_rate' do
    indexes stats(:rating), :as => :ratings, :sortable => true
  end

But this, will generate an index for all :skin_id (in the Stat model), not for particular one.

In other words, i need to gather all items, sorted by Stat.rating, with Stat.skin_id == 1 (for example).

Here is the example of SQL:

"SELECT `stats`.* FROM `stats` INNER JOIN `items` ON `items`.`id` = `stats`.`item_id` WHERE `stats`.`skin_id` = 1 ORDER BY rating DESC"

ANy solutions is very appreciated!

Perhaps you should have in your define_index block:

has :skin_id

and then, when searching, filter by that. Something like this:

Item.search(:with => {:skin_id => skin.id}, :order_by => 'ratings ASC')