ActionController::Renderer allows you to render arbitrary templates without requirement of being in controller actions.

You get a concrete renderer class by invoking ActionController::Base#renderer. For example:


It allows you to call method render directly.

ApplicationController.renderer.render template: '...'

You can use this shortcut in a controller, instead of the previous example:

ApplicationController.render template: '...'

render allows you to use the same options that you can use when rendering in a controller. For example:

FooController.render :action, locals: { ... }, assigns: { ... }

The template will be rendered in a Rack environment which is accessible through ActionController::Renderer#env. You can set it up in two ways:

  • by changing renderer defaults, like

    ApplicationController.renderer.defaults # => hash with default Rack environment
  • by initializing an instance of renderer by passing it a custom environment. 'post', https: true)



DEFAULTS = { http_host: "", https: false, method: "get", script_name: "", input: "" }.freeze
IDENTITY = ->(_) { _ }
RACK_KEY_TRANSLATION = { http_host: "HTTP_HOST", https: "HTTPS", method: "REQUEST_METHOD", script_name: "SCRIPT_NAME", input: "rack.input" }
RACK_VALUE_TRANSLATION = { https: ->(v) { v ? "on" : "off" }, method: ->(v) { v.upcase }, }


[R] controller
[R] defaults

Class Public methods

for(controller, env = {}, defaults = DEFAULTS.dup)

Create a new renderer instance for a specific controller class.

# File actionpack/lib/action_controller/renderer.rb, line 50
def self.for(controller, env = {}, defaults = DEFAULTS.dup)
  new(controller, env, defaults)

new(controller, env, defaults)

Accepts a custom Rack environment to render templates in. It will be merged with the default Rack environment defined by ActionController::Renderer::DEFAULTS.

# File actionpack/lib/action_controller/renderer.rb, line 67
def initialize(controller, env, defaults)
  @controller = controller
  @defaults = defaults
  @env = normalize_keys defaults.merge(env)

Instance Public methods

new(env = {})

Create a new renderer for the same controller but with a new env.

# File actionpack/lib/action_controller/renderer.rb, line 55
def new(env = {}) controller, env, defaults


Render templates with any options from ActionController::Base#render_to_string.

# File actionpack/lib/action_controller/renderer.rb, line 74
def render(*args)
  raise "missing controller" unless controller

  request = @env
  request.routes = controller._routes

  instance =
  instance.set_request! request
  instance.set_response! controller.make_response!(request)


Create a new renderer for the same controller but with new defaults.

# File actionpack/lib/action_controller/renderer.rb, line 60
def with_defaults(defaults) controller, @env, self.defaults.merge(defaults)