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| -rwxr-xr-x | activerecord/lib/active_record/associations.rb | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb index 961f7cc30e..93f10c666c 100755 --- a/activerecord/lib/active_record/associations.rb +++ b/activerecord/lib/active_record/associations.rb @@ -279,6 +279,30 @@ module ActiveRecord # 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 |