Refactor AssociationScope#get_bind_values

Added #join_id_for(owner) to reflection to avoid accessing the source_macro

activerecord/lib/active_record/associations/association_scope.rb

@@ -47,15 +47,8 @@ def join_type
       def self.get_bind_values(owner, chain)
         bvs = []
         chain.each_with_index do |reflection, i|
-          if reflection.source_macro == :belongs_to
-            foreign_key = reflection.foreign_key
-          else
-            foreign_key = reflection.active_record_primary_key
-          end
-
           if reflection == chain.last
-            bvs << owner[foreign_key]
-
+            bvs << reflection.join_id_for(owner)
             if reflection.type
               bvs << owner.class.base_class.name
             end

activerecord/lib/active_record/reflection.rb

@@ -278,6 +278,11 @@ def check_validity_of_inverse!
         end
       end
 
+      def join_id_for(owner) #:nodoc:
+        key = (source_macro == :belongs_to) ? foreign_key : active_record_primary_key
+        owner[key]
+      end
+
       def through_reflection
         nil
       end