forgetting_assignment

# File activemodel/lib/active_model/attribute.rb, line 178
        def forgetting_assignment
          # If this attribute was not persisted (with a `value_for_database`
          # that might differ from `value_before_type_cast`) and `value` has not
          # changed in place, we can use the existing `value_before_type_cast`
          # to avoid deserialize / cast / serialize calls from computing the new
          # attribute's `value_before_type_cast`.
          if !defined?(@value_for_database) && !changed_in_place?
            with_value_from_database(value_before_type_cast)
          else
            super
          end
        end