Polymorphic join support for has_one associations (has_one :foo, :as => :bar). Closes #3785.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@3558 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

2 files changed, 9 insertions, 3 deletions

diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index 6b461b5514..0dc03487cb 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -899,7 +899,7 @@ module ActiveRecord
 
         def create_has_one_reflection(association_id, options)
           options.assert_valid_keys(
-            :class_name, :foreign_key, :remote, :conditions, :order, :include, :dependent, :counter_cache, :extend
+            :class_name, :foreign_key, :remote, :conditions, :order, :include, :dependent, :counter_cache, :extend, :as
           )
 
           reflection = create_reflection(:has_one, association_id, options, self)
diff --git a/activerecord/lib/active_record/associations/has_one_association.rb b/activerecord/lib/active_record/associations/has_one_association.rb
index 17483305fc..4dbc0f6441 100644
--- a/activerecord/lib/active_record/associations/has_one_association.rb
+++ b/activerecord/lib/active_record/associations/has_one_association.rb
@@ -66,9 +66,15 @@ module ActiveRecord
         end
 
         def construct_sql
-          @finder_sql = "#{@reflection.table_name}.#{@reflection.primary_key_name} = #{@owner.quoted_id}"
+          case
+            when @reflection.options[:as]
+              @finder_sql = 
+                "#{@reflection.klass.table_name}.#{@reflection.options[:as]}_id = #{@owner.quoted_id} AND " + 
+                "#{@reflection.klass.table_name}.#{@reflection.options[:as]}_type = '#{ActiveRecord::Base.send(:class_name_of_active_record_descendant, @owner.class).to_s}'"          
+            else
+              @finder_sql = "#{@reflection.table_name}.#{@reflection.primary_key_name} = #{@owner.quoted_id}"
+          end
           @finder_sql << " AND (#{sanitize_sql(@reflection.options[:conditions])})" if @reflection.options[:conditions]
-          @finder_sql
         end
     end
   end