Using :through and belongs_to

I'm trying to reduce the mysql calls by using :include or :through and both methods don't seem to work.

Here's the breakdown: users can have friends and an avatar (image), so my models are setup like this:

  User     has_many :images, :as => :imageable     has_many :friends

  Image     belongs_to :imageable, :polymorphic => true

  Friend     # The user     belongs_to :owner_user, :class_name => "User", :foreign_key => "user_id",

    # The friend     belongs_to :user, :class_name => "User", :foreign_key => "friend_id"

When I list all of the User's friends with their avatars, a MySql query is made for each friend image. This adds up to a lot of mysql requests. So my first plan was to add :include to the Friend association:

  Friend     # The friend     belongs_to :user, :class_name => "User", :foreign_key => "friend_id", :include => :images

For some reason this did not reduce the nubmer of mysql queries, so I tried a :through association:

  Friend     # The friend     belongs_to :user, :class_name => "User", :foreign_key => "friend_id"

    has_many :images, :through => :user, :limit => 1

Now I get the following error (most likely do to the foreign_key in the belongs_to association):

Mysql::Error: Unknown column 'users.friend_id' in 'where clause': SELECT images.* FROM images INNER JOIN users ON images.imageable_id = AND images.imageable_type = 'User' WHERE ((users.friend_id = 2)) LIMIT 1

Why is it mapping the foreign_key incorrectly? Is it because I'm pointing the :through to a belongs_to association? I would appreciate any solution to this issue.

Thanks, Jeremy

I’m actually having this exact same problem. Anyone know how to set up this polymorphic through association?