ActiveRecord: save_only_valid_attributes ?

Hello,

I've been going through the Rails code today, looking for a method that will allow me to save an invalid record, but only update attributes that do not have errors attached. (i.e. model.errors.on(:attribute) is nil).

Any ideas on how to accomplish this would be appreciated. If this isn't a part of Rails, I think it would be used enough to be a good idea for a patch.

Thanks, Brady