initialize_attributes

# File activerecord/lib/active_record/associations/association.rb, line 166
      def initialize_attributes(record, except_from_scope_attributes = nil) #:nodoc:
        except_from_scope_attributes ||= {}
        skip_assign = [reflection.foreign_key, reflection.type].compact
        assigned_keys = record.changed
        assigned_keys += except_from_scope_attributes.keys.map(&:to_s)
        attributes = create_scope.except(*(assigned_keys - skip_assign))
        record.assign_attributes(attributes)
        set_inverse_instance(record)
      end