gistfile1.rb

require 'uri/http'

# Blatently stolen from http://www.simonecarletti.com/blog/2009/04/validating-the-format-of-an-url-with-rails/
#
# Validates whether the value of the specified attribute matches the format of an URL,
# as defined by RFC 2396. See URI#parse for more information on URI decompositon and parsing.
#
# This method doesn't validate the existence of the domain, nor it validates the domain itself.
#
# Allowed values include http://foo.bar, http://www.foo.bar and even http://foo.
# Please note that http://foo is a valid URL, as well http://localhost.
# It's up to you to extend the validation with additional constraints.
#
#   class Site < ActiveRecord::Base
#     validates_format_of :url, :on => :create
#     validates_format_of :ftp, :schemes => [:ftp, :http, :https]
#   end
#
# ==== Configurations
#
# * :schemes - An array of allowed schemes to match against (default is [:http, :https])
# * :message - A custom error message (default is: "is invalid").
# * :allow_nil - If set to true, skips this validation if the attribute is +nil+ (default is +false+).
# * :allow_blank - If set to true, skips this validation if the attribute is blank (default is +false+).
# * :on - Specifies when this validation is active (default is :save, other options :create, :update).
# * :if - Specifies a method, proc or string to call to determine if the validation should
#   occur (e.g. :if => :allow_validation, or :if => Proc.new { |user| user.signup_step > 2 }).  The
#   method, proc or string should return or evaluate to a true or false value.
# * :unless - Specifies a method, proc or string to call to determine if the validation should
#   not occur (e.g. :unless => :skip_validation, or :unless => Proc.new { |user| user.signup_step <= 2 }).  The
#   method, proc or string should return or evaluate to a true or false value.
#
#
class UrlValidator < ActiveModel::EachValidator
  def validate_each(record, attribute, value, options = {})
    default_options = {
      schemes: [:http, :https]
    }

    settings = default_options.merge(options.symbolize_keys)

    uri = URI.parse(value)

    unless settings[:schemes].include?(uri.scheme.try(:to_sym))
      add_error_message(record, attribute, value, settings)
    end

    if [:scheme, :host].any? { |i| uri.send(i).blank? }
      add_error_message(record, attribute, value, settings)
    end
  rescue URI::InvalidURIError => e
    add_error_message(record, attribute, value, settings)
  end

  def add_error_message(record, attr_name, value, settings)
    record.errors.add(attr_name, :invalid, :default => settings[:message], :value => value)
  end
end