I have a boolean attribute on a model ... user_approved ... that I
wish to apply some validation to upon update ...
The business rule is "You cannot update this model to user_approved if
it already has been" .... but I am not sure if I can do this using the
normal rails validations?
For example, using update_attributes, how do I tell that they have
requested to update this field as opposed to updating another?
Anyone have any elegant solutions?