class ActionDispatch::Request::Utils

def self.check_param_encoding(params)
  case params
  when Array
    params.each { |element| check_param_encoding(element) }
  when Hash
    params.each_value { |value| check_param_encoding(value) }
  when String
    unless params.valid_encoding?
      # Raise Rack::Utils::InvalidParameterError for consistency with Rack.
      # ActionDispatch::Request#GET will re-raise as a BadRequest error.
      raise Rack::Utils::InvalidParameterError, "Invalid encoding for parameter: #{params.scrub}"
    end
  end
end