rails validation regular expression for www and http

I want to validate a form input so that http:// and www is not allowed. Which REGEX would work?

For example:



NOT Allowed

  • www.google.com
  • http://google.com
  • http://www.google.com



validates :domain, format: { with: VALID_DOMAIN_REGEX }

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  • 2 Solutions collect form web for “rails validation regular expression for www and http”

    Since http:// contains so many forward slashes, this would be a good use for Ruby’s %r{} regex literal syntax.

    def has_forbidden_prefix?(string)
      string =~ %r{^(http://|www)}

    This will return nil, falsy, if the string does not start with http:// or www.

    It will return 0, truthy (the offset of the first match) if the string does.

    You can use validate :some_method_name to call a custom validation method in the model, I would structure it as follows

    model MyThing
      validate :no_forbidden_prefix
      def has_forbidden_prefix?(string)
        string =~ %r{^(http://|www)}
      def no_forbidden_prefix
        if has_forbidden_prefix?(uri)
          errors.add :domain, 'The URI cannot start with "http://" or "www"'

    This should do it for you:


    For example:

    1.9.2p320 :007 > "http://www.google.de".match /^[http\:\/\/|www].*/
     => #<MatchData "http://www.google.de">
    1.9.2p320 :008 > "www.google.de".match /^[http\:\/\/|www].*/
     => #<MatchData "www.google.de">
    1.9.2p320 :009 > "google.de".match /^[http\:\/\/|www].*/
     => nil

    So it doenst match if its valid for your purposes…

    Ruby is the best programming language in the world - Ruby on Rails.