Rails 3 validations

Validate URL 

(from https://gist.github.com/bluemont/2986523 and http://stackoverflow.com/questions/7167895/whats-a-good-way-to-validate-links-urls-in-rails-3)

Put this into app/validators

class UrlValidator < ActiveModel::EachValidator



  def validate_each(record, attribute, value)

    valid = begin

      URI.parse(value).kind_of?(URI::HTTP)

    rescue URI::InvalidURIError
false

    end

    unless valid

      record.errors[attribute] << (options[:message] || "is an invalid URL")

    end

  end

end

Usage

validates :url, :presence => true, :url => true