Class: ActionController::Metal

Relationships & Source Files
Extension / Inclusion / Inheritance Descendants
Subclasses: API, Base, Rails::ApplicationController, Rails::HealthController, Rails::InfoController, Rails::MailersController, Rails::PwaController, Rails::WelcomeController, ActionView::TestCase::TestController
Super Chains via Extension / Inclusion / Inheritance
Class Chain: self, `::AbstractController::Base`, `::ActiveSupport::DescendantsTracker`
Instance Chain: self, `::AbstractController::Base`, `::ActiveSupport::Configurable`
Inherits:	AbstractController::Base `::Object` AbstractController::Base ActionController::Metal
Defined in:	actionpack/lib/action_controller/metal.rb, actionpack/lib/action_controller/test_case.rb

Overview

Metal is the simplest possible controller, providing a valid ::Rack interface without the additional niceties provided by Base.

A sample metal controller might look like this:

class HelloController < ActionController::Metal
  def index
    self.response_body = "Hello World!"
  end
end

And then to route requests to your metal controller, you would add something like this to config/routes.rb:

get 'hello', to: HelloController.action(:index)

The .action method returns a valid ::Rack application for the ::Rails router to dispatch to.

Rendering Helpers

By default, Metal provides no utilities for rendering views, partials, or other responses aside from some low-level setters such as #response_body=, #content_type=, and #status=. To add the render helpers you’re used to having in a normal controller, you can do the following:

class HelloController < ActionController::Metal
  include AbstractController::Rendering
  include ActionView::Layouts
  append_view_path "#{Rails.root}/app/views"

  def index
    render "hello/index"
  end
end

Redirection Helpers

To add redirection helpers to your metal controller, do the following:

class HelloController < ActionController::Metal
  include ActionController::Redirecting
  include Rails.application.routes.url_helpers

  def index
    redirect_to root_url
  end
end

Other Helpers

You can refer to the modules included in Base to see other features you can bring into your metal controller.

`::AbstractController::Base` - Inherited

.abstract?	Alias for AbstractController::Base.abstract.
.supports_path?	Returns true if the given controller is capable of rendering a path.

Class Method Summary

.action(name)

Returns a ::Rack endpoint for the given action name.
.controller_name

Returns the last part of the controller’s name, underscored, without the ending Controller.
.dispatch(name, req, res)

Direct dispatch to the controller.
.make_response!(request)
.middleware

The middleware stack used by this controller.
.new ⇒ Metal constructor
.use

Pushes the given ::Rack middleware and its arguments to the bottom of the middleware stack.

`::AbstractController::Base` - Inherited

.abstract,
.abstract!	Define a controller as abstract.
.action_methods	A list of method names that should be considered actions.
.clear_action_methods!	action_methods are cached and there is sometimes a need to refresh them.
.controller_path	Returns the full controller name, underscored, without the ending Controller.
.internal_methods	A list of all internal methods for a controller.
.method_added	Refresh the cached action_methods when a new action_method is added.

`::ActiveSupport::DescendantsTracker` - Extended

descendants

Instance Attribute Summary

#content_type rw
#headers readonly
#location rw
#media_type readonly
#middleware_stack rw
#middleware_stack? ⇒ Boolean rw
#params rw
#params=(val) rw
#performed? ⇒ Boolean readonly

Tests if render or redirect has already happened.
#request rw

:attr_reader: request.
#response rw

:attr_reader: response.
#response=(response) rw

Assign the response and mark it as committed.
#response_body=(body) writeonly
#session readonly
#status (also: #response_code) rw

`::AbstractController::Base` - Inherited

#action_name	Returns the name of the action this controller is processing.
#formats	Returns the formats that can be processed by the controller.
#performed?	Tests if a response body is set.
#response_body	Returns the body of the HTTP response sent by the controller.

Instance Method Summary

#controller_name

Delegates to the class’s .controller_name.
#reset_session
#url_for(string)

Basic #url_for that can be overridden for more robust functionality.

`::AbstractController::Base` - Inherited

#action_methods	Delegates to the class’s `.action_methods`.
#available_action?	Returns true if a method for the action is available and can be dispatched, false otherwise.
#controller_path	Delegates to the class’s `.controller_path`.
#process	Calls the action going through the entire Action Dispatch stack.

`::ActiveSupport::Configurable` - Included

#config

Reads and writes attributes from a configuration OrderedOptions.

Constructor Details

.new ⇒ `Metal`

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 210


def initialize
  @_request = nil
  @_response = nil
  @_response_body = nil
  @_routes = nil
  @_params = nil
  super
end

Class Attribute Details

.middleware_stack (rw)

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 288


class_attribute :middleware_stack, default: ActionController::MiddlewareStack.new

.middleware_stack? ⇒ `Boolean` (rw)

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 288


class_attribute :middleware_stack, default: ActionController::MiddlewareStack.new

Class Method Details

.action(name)

Returns a ::Rack endpoint for the given action name.

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 315


def self.action(name)
  app = lambda { |env|
    req = ActionDispatch::Request.new(env)
    res = make_response! req
    new.dispatch(name, req, res)
  }

  if middleware_stack.any?
    middleware_stack.build(name, app)
  else
    app
  end
end

.controller_name

Returns the last part of the controller’s name, underscored, without the ending Controller. For instance, PostsController returns posts. Namespaces are left out, so Admin::PostsController returns posts as well.

#### Returns

string

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 130


def self.controller_name
  @controller_name ||= (name.demodulize.delete_suffix("Controller").underscore unless anonymous?)
end

.dispatch(name, req, res)

Direct dispatch to the controller. Instantiates the controller, then executes the action named name.

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 331


def self.dispatch(name, req, res)
  if middleware_stack.any?
    middleware_stack.build(name) { |env| new.dispatch(name, req, res) }.call req.env
  else
    new.dispatch(name, req, res)
  end
end

.make_response!(request)

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 134


def self.make_response!(request)
  ActionDispatch::Response.new.tap do |res|
    res.request = request
  end
end

.middleware

The middleware stack used by this controller.

By default uses a variation of ::ActionDispatch::MiddlewareStack which allows for the following syntax:

class PostsController < ApplicationController
  use AuthenticationMiddleware, except: [:index, :show]
end

Read more about [Rails middleware stack] (guides.rubyonrails.org/rails_on_rack.html#action-dispatcher-middleware-stack) in the guides.

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 310


def self.middleware
  middleware_stack
end

.use

Pushes the given ::Rack middleware and its arguments to the bottom of the middleware stack.

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 293


def use(...)
  middleware_stack.use(...)
end

Instance Attribute Details

#content_type (rw)

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 204


delegate :content_type, to: "@_response"

#headers (readonly)

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 180


delegate :headers, to: "@_response"

#location (rw)

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 200


delegate :location, to: "@_response"

#media_type (readonly)

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 208


delegate :media_type, to: "@_response"

#middleware_stack (rw)

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 288


class_attribute :middleware_stack, default: ActionController::MiddlewareStack.new

#middleware_stack? ⇒ `Boolean` (rw)

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 288


class_attribute :middleware_stack, default: ActionController::MiddlewareStack.new

#params (rw)

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 219


def params
  @_params ||= request.parameters
end

#params=(val) (rw)

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 223


def params=(val)
  @_params = val
end

#performed? ⇒ `Boolean` (readonly)

Tests if render or redirect has already happened.

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 245


def performed?
  response_body || response.committed?
end

#request (rw)

:attr_reader: request

The ::ActionDispatch::Request instance for the current request.

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 164


attr_internal :request

#response (rw)

:attr_reader: response

The ::ActionDispatch::Response instance for the current response.

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 170


attr_internal_reader :response

#response=(response) (rw)

Assign the response and mark it as committed. No further processing will occur.

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 268


def response=(response)
  set_response!(response)

  # Force `performed?` to return true:
  @_response_body = true
end

#response_body=(body) (writeonly)

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 234


def response_body=(body)
  if body
    body = [body] if body.is_a?(String)
    response.body = body
    super
  else
    response.reset_body!
  end
end

#session (readonly)

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 176


delegate :session, to: "@_request"

#status (rw) Also known as: #response_code

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 196


delegate :status, to: "@_response"

Instance Method Details

#controller_name

Delegates to the class’s .controller_name.

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 156


def controller_name
  self.class.controller_name
end

#reset_session

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 284


def reset_session
  @_request.reset_session
end

#url_for(string)

Basic url_for that can be overridden for more robust functionality.

[ GitHub ]

# File 'actionpack/lib/action_controller/metal.rb', line 230


def url_for(string)
  string
end

Class: ActionController::Metal

Overview

Rendering Helpers

Redirection Helpers

Other Helpers

Class Attribute Summary

::AbstractController::Base - Inherited

Class Method Summary

::AbstractController::Base - Inherited

::ActiveSupport::DescendantsTracker - Extended

Instance Attribute Summary

::AbstractController::Base - Inherited

Instance Method Summary

::AbstractController::Base - Inherited

::ActiveSupport::Configurable - Included

Constructor Details

.new ⇒ Metal

Class Attribute Details

.middleware_stack (rw)

.middleware_stack? ⇒ Boolean (rw)

Class Method Details

.action(name)

.controller_name

.dispatch(name, req, res)

.make_response!(request)

.middleware

.use

Instance Attribute Details

#content_type (rw)

#headers (readonly)

#location (rw)

#media_type (readonly)

#middleware_stack (rw)

#middleware_stack? ⇒ Boolean (rw)

#params (rw)

#params=(val) (rw)

#performed? ⇒ Boolean (readonly)

#request (rw)

#response (rw)

#response=(response) (rw)

#response_body=(body) (writeonly)

#session (readonly)

#status (rw) Also known as: #response_code

Instance Method Details

#controller_name

#reset_session

#url_for(string)

`::AbstractController::Base` - Inherited

`::AbstractController::Base` - Inherited

`::ActiveSupport::DescendantsTracker` - Extended

`::AbstractController::Base` - Inherited

`::AbstractController::Base` - Inherited

`::ActiveSupport::Configurable` - Included

.new ⇒ `Metal`

.middleware_stack? ⇒ `Boolean` (rw)

#middleware_stack? ⇒ `Boolean` (rw)

#performed? ⇒ `Boolean` (readonly)