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Docfix (closes #6040)

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@5259 5ecf4fe2-1ee6-0310-87b1-e25e094e27de
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commit fc7fd4c5cee277d569fd406c55fc9d147ca000c1 1 parent 943be92
@dhh dhh authored
Showing with 24 additions and 0 deletions.
  1. +24 −0 activerecord/lib/active_record/associations.rb
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24 activerecord/lib/active_record/associations.rb
@@ -279,6 +279,30 @@ def clear_association_cache #:nodoc:
# This works by using a type column in addition to a foreign key to specify the associated record. In the Asset example, you'd need
# an attachable_id integer column and an attachable_type string column.
#
+ # Using polymorphic associations in combination with single table inheritance (STI) is a little tricky. In order
+ # for the associations to work as expected, ensure that you store the base model for the STI models in the
+ # type column of the polymorphic association. To continue with the asset example above, suppose there are guest posts
+ # and member posts that use the posts table for STI. So there will be an additional 'type' column in the posts table.
+ #
+ # class Asset < ActiveRecord::Base
+ # belongs_to :attachable, :polymorphic => true
+ #
+ # def attachable_type=(sType)
+ # super(sType.to_s.classify.constantize.base_class.to_s)
+ # end
+ # end
+ #
+ # class Post < ActiveRecord::Base
+ # # because we store "Post" in attachable_type now :dependent => :destroy will work
+ # has_many :assets, :as => :attachable, :dependent => :destroy
+ # end
+ #
+ # class GuestPost < ActiveRecord::Base
+ # end
+ #
+ # class MemberPost < ActiveRecord::Base
+ # end
+ #
# == Caching
#
# All of the methods are built on a simple caching principle that will keep the result of the last query around unless specifically
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