Several polymorphic associations using class_name? - activerecord

Question

I am trying to create an article which holds in_prices and out_prices (one for each country) using rails polymorphic associations and nested forms.
I have a data model which looks something like this:
# app/models/article.rb
class Article < ActiveRecord::Base
has_many :out_prices, :class_name => "Price", :as => :priceable
has_many :in_prices, :class_name => "Price", :as => :priceable
end
# app/models/price.rb
class Price < ActiveRecord::Base
belongs_to :priceable, :polymorphic => true
end
# db.schema for prices
create_table "prices", :force => true do |t|
t.integer "value"
t.integer "country_id"
t.integer "priceable_id"
t.string "priceable_type"
end
The article and its associations are created using a nested form like:
# app/views/articles/_article_form.html.erb
<%= form_for setup_article(#article) do |f| %>
<%= f.fields_for :in_prices do |ff| %>
<%= ff.text_field :value %>
<% end %>
<%= f.fields_for :out_prices do |ff| %>
<%= ff.text_field :value %>
<% end %>
<% end %>
The setup_article method is a helper method to build the associations:
# app/helpers/articles_helper.rb
def setup_article(article)
if article.in_prices.nil?
# Setup one in price for each country
Country.all.each do |country|
article.in_prices.build(:value => 0, :country_id => country.id)
end
end
if article.out_prices.nil?
# Setup one out price for each country
Country.all.each do |country|
article.out_prices.build(:value => 0, :country_id => country.id)
end
end
article
end
setup_article is needed to make sure empty price form fields (one for each country) shows up when creating a new article.
Now to the actual problem. When I edit an already created Article (which have associated in_prices and out_prices) Rails won't be able to differentiate between these different types of polymorphic associations (in_prices and out_prices). Because of this both nested form helpers renderes form fields for all associated prices, which isn't the desired behavior. I only want to list in_prices in the one of the nested forms, and the out_prices in the other.
How should these associations be configured to make sure rails can differentiate between the in_prices and out_prices associations in the two different nested form helpers?
EDIT (SOLVED)
A friend of mine pointed out I need to add yet another field in the prices table to flag what type of price it is. I called this field price_type and the db.schema ended up looking like this:
# db.schema for prices
create_table "prices", :force => true do |t|
t.integer "value"
t.integer "price_type"
t.integer "country_id"
t.integer "priceable_id"
t.string "priceable_type"
end
Note: Don't name this field 'type' since this is a reserved name.
The 'price_type' field can be populated either by adding a hidden field in the nested forms (less safe), or to handle it in the controller before saving the article and its associated data. I chose to add it as hidden params like:
# app/views/articles/_article_form.html.erb
<%= form_for setup_article(#article) do |f| %>
<%= f.fields_for :in_prices do |ff| %>
<%= ff.text_field :value %>
<%= ff.text_field :price_type, :value => "in" %>
<% end %>
<%= f.fields_for :out_prices do |ff| %>
<%= ff.text_field :value %>
<%= ff.text_field :price_type, :value => "out" %>
<% end %>
<% end %>
To make sure the associations gets filtered correctly they need to be declared with the ':conditions' tag, like:
# app/models/article.rb
class Article < ActiveRecord::Base
has_many :out_prices, :class_name => "Price", :as => :priceable, :conditions => { :price_type => "in" }
has_many :in_prices, :class_name => "Price", :as => :priceable, :conditions => { :price_type => "out" }
end
.. and now everything works as expected. cheers!