Simple rails format validation not firing

Question

I'm building an app where users can create url slugs for their profile. To make sure the slugs are valid I've added a validation in the User model for slugs:

  validates :slug, :uniqueness => true, :format => { :with => /[a-z]+/ }, :allow_nil => true, :allow_blank => true

However, validation seems to pass, regardless of what format the slug string is, for example:

u.slug = 'jlskdf .jc oi/slkdjfie\*asdf&(*&*ss%&'
=> "jlskdf .jc oi/slkdjfie\\*asdf&(*&*ss%&"
u.save
=> true

Apparently it doesn't matter what I change the regex to either, everything passes. I've tried this format as well:

validates_format_of :slug, :with => /[a-z]+/

which gives the same results. Anyone have any ideas of what could be happening?

Answer 1

Your regular expression isn't anchored, so the pattern matches as long as it contains at least one letter a-z. Anything else is valid. Add \A and \z to the beginning and end to prevent matching any substring within the larger input.

:with => /\A[a-z]+\z/