module ActionController::Head

def head(status, options = {})

See Rack::Utils::SYMBOL_TO_STATUS_CODE for a full list of valid +status+ symbols.

render
return head(:bad_request) unless valid_request?
return head(:method_not_allowed) unless request.post?

It can also be used to return exceptional conditions:

head :created, location: @person

head :created, location: person_path(@person)

significant headers:
This allows you to easily return a response that consists only of
argument is interpreted to be a hash of header names and values.
Returns a response that has no content (merely headers). The options 
def head(status, options = {})
  if status.is_a?(Hash)
    msg = status[:status] ? 'The :status option' : 'The implicit :ok status'
    options, status = status, status.delete(:status)
    ActiveSupport::Deprecation.warn(<<-MSG.squish)
      #{msg} on `head` has been deprecated and will be removed in Rails 5.1.
      Please pass the status as a separate parameter before the options, instead.
    MSG
  end
  status ||= :ok
  location = options.delete(:location)
  content_type = options.delete(:content_type)
  options.each do |key, value|
    headers[key.to_s.dasherize.split('-').each { |v| v[0] = v[0].chr.upcase }.join('-')] = value.to_s
  end
  self.status = status
  self.location = url_for(location) if location
  self.response_body = ""
  if include_content?(self.response_code)
    self.content_type = content_type || (Mime[formats.first] if formats)
    self.response.charset = false
  end
  true
end

def include_content?(status) 

def include_content?(status)
  case status
  when 100..199
    false
  when 204, 205, 304
    false
  else
    true
  end
end