Question

How would you validate a screen name using regex (on Ruby on Rails)?

I’m looking for a bit of regex to validate (in an RoR model) that a screen name does not have any symbols or spaces in it.

Answer 1

It sounds like you want to specify a blacklist of characters that aren’t allowed, but there are a lot of characters out there that you probably don’t want in screen names so it would be better to use a whitelist. Here’s an example that would only allow letters, numbers, and underscores in screen names and restrict the length to be 2-30:

class User < ActiveRecord::Base
    validates_format_of :screen_name, :with => /\A[a-zA-Z0-9_]{2,30}\Z/
end