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

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

ApplicationController.renderer

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.

    ApplicationController.renderer.new(method: 'post', https: true)
Methods
F
N
R
W
Constants
DEFAULTS = { http_host: 'example.org', https: false, method: 'get', script_name: '', input: '' }.freeze
 
RACK_KEY_TRANSLATION = { http_host: 'HTTP_HOST', https: 'HTTPS', method: 'REQUEST_METHOD', script_name: 'SCRIPT_NAME', input: 'rack.input' }
 
IDENTITY = ->(_) { _ }
 
RACK_VALUE_TRANSLATION = { https: ->(v) { v ? 'on' : 'off' }, method: ->(v) { v.upcase }, }
 
Attributes
[R] controller
[R] defaults
Class Public methods
for(controller, env = {}, defaults = DEFAULTS.dup)

Create a new renderer instance for a specific controller class.

Source: show | on GitHub 

# File actionpack/lib/action_controller/renderer.rb, line 48
def self.for(controller, env = {}, defaults = DEFAULTS.dup)
  new(controller, env, defaults)
end
new(controller, env, defaults)

Accepts a custom Rack environment to render templates in. It will be merged with #defaults

Source: show | on GitHub 

# File actionpack/lib/action_controller/renderer.rb, line 64
def initialize(controller, env, defaults)
  @controller = controller
  @defaults = defaults
  @env = normalize_keys defaults.merge(env)
end
Instance Public methods
new(env = {})

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

Source: show | on GitHub 

# File actionpack/lib/action_controller/renderer.rb, line 53
def new(env = {})
  self.class.new controller, env, defaults
end
render(*args)

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

Source: show | on GitHub 

# File actionpack/lib/action_controller/renderer.rb, line 71
def render(*args)
  raise 'missing controller' unless controller

  request = ActionDispatch::Request.new @env
  request.routes = controller._routes

  instance = controller.new
  instance.set_request! request
  instance.set_response! controller.make_response!(request)
  instance.render_to_string(*args)
end
with_defaults(defaults)

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

Source: show | on GitHub 

# File actionpack/lib/action_controller/renderer.rb, line 58
def with_defaults(defaults)
  self.class.new controller, env, self.defaults.merge(defaults)
end