convert to utf-8 using iconv fallback when String#encode doesn't work

gistfile1.rb

require "iconv"

def sanitize_utf8(string)
  string = string.encode("UTF-8", :invalid => :replace, :undef => :replace)
  begin
    string.blank? # Assume you're using ActiveSupport
  rescue ArgumentError => e
    if e.message == "invalid byte sequence in UTF-8"
      Thread.current["iconv"] ||= Iconv.new('UTF-8//IGNORE', 'UTF-8')
      string = Thread.current["iconv"].iconv(string)
    else
      raise
    end
  end
  string
end