Add foreign_type option for polymorphic has_one and has_many.

To be possible to use a custom column name to save/read the polymorphic
associated type in a has_many or has_one polymorphic association, now users
can use the option :foreign_type to inform in what column the associated object
type will be saved.

2 files changed, 6 insertions, 0 deletions

diff --git a/activerecord/test/models/image.rb b/activerecord/test/models/image.rb
new file mode 100644
index 0000000000..7ae8e4a7f6
--- /dev/null
+++ b/activerecord/test/models/image.rb
@@ -0,0 +1,3 @@
+class Image < ActiveRecord::Base
+  belongs_to :imageable, foreign_key: :imageable_identifier, foreign_type: :imageable_class
+end
diff --git a/activerecord/test/models/post.rb b/activerecord/test/models/post.rb
index 57e1818e49..56073cc588 100644
--- a/activerecord/test/models/post.rb
+++ b/activerecord/test/models/post.rb
@@ -128,6 +128,9 @@ class Post < ActiveRecord::Base
   has_many :taggings_using_author_id, :primary_key => :author_id, :as => :taggable, :class_name => 'Tagging'
   has_many :tags_using_author_id, :through => :taggings_using_author_id, :source => :tag
 
+  has_many :images, :as => :imageable, :foreign_key => :imageable_identifier, :foreign_type => :imageable_class
+  has_one :main_image, :as => :imageable, :foreign_key => :imageable_identifier, :foreign_type => :imageable_class, :class_name => 'Image'
+
   has_many :standard_categorizations, :class_name => 'Categorization', :foreign_key => :post_id
   has_many :author_using_custom_pk,  :through => :standard_categorizations
   has_many :authors_using_custom_pk, :through => :standard_categorizations