1 files changed, 6 insertions, 2 deletions
diff --git a/activerecord/lib/active_record/associations/has_many_through_association.rb b/activerecord/lib/active_record/associations/has_many_through_association.rb
index 64bc98c642..73baefb8e1 100644
--- a/activerecord/lib/active_record/associations/has_many_through_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_through_association.rb
@@ -18,7 +18,7 @@ module ActiveRecord
       # SELECT query if you use #length.
       def size
         if has_cached_counter?
-          owner.send(:read_attribute, cached_counter_attribute_name)
+          owner.read_attribute cached_counter_attribute_name(reflection)
         elsif loaded?
           target.size
         else
@@ -83,12 +83,16 @@ module ActiveRecord
           @through_records[record.object_id] ||= begin
             ensure_mutable
 
-            through_record = through_association.build
+            through_record = through_association.build through_scope_attributes
             through_record.send("#{source_reflection.name}=", record)
             through_record
           end
         end
 
+        def through_scope_attributes
+          scope.where_values_hash(through_association.reflection.name.to_s)
+        end
+
         def save_through_record(record)
           build_through_record(record).save!
         ensure