"must be nil" validation?

rubyonrails-talk
1

Hey guys, is there a validation that essentially acts the opposite way of "validates_presence_of". That is, the attribute in question must be nil, or blank, non-existent. If not, what's the best way to prevent a user from altering a web form attempting to submit data to a field that they should never have access to?

Thanks!

2

Seirie wrote:

Hey guys, is there a validation that essentially acts the opposite way of "validates_presence_of". That is, the attribute in question must be nil, or blank, non-existent. If not, what's the best way to prevent a user from altering a web form attempting to submit data to a field that they should never have access to?

What you're looking for is attr_accessible and/or attr_protected:

http://railsapi.com/doc/rails-v2.3.5/classes/ActiveRecord/Base.html#M000920

If you were to do that in validation it would render the attribute virtually useless. You would have to bypass validation altogether in order to set it at all. What you really want is to disallow mass assignment of the attribute. That's what the above methods do.

3

brilliant, exactly what I was looking for. Thank you much Robert.