ActionController::Metal is the simplest possible controller, providing a valid Rack interface without the additional niceties provided by ActionController::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:
match 'hello', :to => HelloController.action(:index)
The action method returns a valid Rack application for the Rails router to dispatch to.
ActionController::Metal by default provides no utilities for rendering views, partials, or other responses aside from explicitly calling of 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 ActionController::Rendering append_view_path "#{Rails.root}/app/views" def index render "hello/index" end end
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
You can refer to the modules included in ActionController::Base to see other features you can bring into your metal controller.
Return a rack endpoint for the given action. Memoize the endpoint, so multiple calls into MyController.action will return the same object for the same action.
action - An action name
proc - A rack application
# File lib/action_controller/metal.rb, line 244 244: def self.action(name, klass = ActionDispatch::Request) 245: middleware_stack.build(name.to_s) do |env| 246: new.dispatch(name, klass.new(env)) 247: end 248: end
Makes the controller a rack endpoint that points to the action in the given env’s action_dispatch.request.path_parameters key.
# File lib/action_controller/metal.rb, line 231 231: def self.call(env) 232: action(env['action_dispatch.request.path_parameters'][:action]).call(env) 233: end
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.
string
# File lib/action_controller/metal.rb, line 116 116: def self.controller_name 117: @controller_name ||= self.name.demodulize.sub(/Controller$/, '').underscore 118: end
Alias for middleware_stack
# File lib/action_controller/metal.rb, line 225 225: def self.middleware 226: middleware_stack 227: end
# File lib/action_controller/metal.rb, line 159 159: def content_type 160: headers["Content-Type"] 161: end
Basic implementations for content_type=, location=, and headers are provided to reduce the dependency on the RackDelegation module in Renderer and Redirector.
# File lib/action_controller/metal.rb, line 155 155: def content_type=(type) 156: headers["Content-Type"] = type.to_s 157: end
Delegates to the class’ controller_name
# File lib/action_controller/metal.rb, line 121 121: def controller_name 122: self.class.controller_name 123: end
# File lib/action_controller/metal.rb, line 106 106: def env 107: @_env ||= {} 108: end
# File lib/action_controller/metal.rb, line 163 163: def location 164: headers["Location"] 165: end
# File lib/action_controller/metal.rb, line 167 167: def location=(url) 168: headers["Location"] = url 169: end
# File lib/action_controller/metal.rb, line 143 143: def params 144: @_params ||= request.parameters 145: end
# File lib/action_controller/metal.rb, line 147 147: def params=(val) 148: @_params = val 149: end
# File lib/action_controller/metal.rb, line 195 195: def performed? 196: response_body 197: end
# File lib/action_controller/metal.rb, line 184 184: def response_body=(val) 185: body = if val.is_a?(String) 186: [val] 187: elsif val.nil? || val.respond_to?(:each) 188: val 189: else 190: [val] 191: end 192: super body 193: end
# File lib/action_controller/metal.rb, line 176 176: def status 177: @_status 178: end
# File lib/action_controller/metal.rb, line 180 180: def status=(status) 181: @_status = Rack::Utils.status_code(status) 182: end
basic url_for that can be overridden for more robust functionality
# File lib/action_controller/metal.rb, line 172 172: def url_for(string) 173: string 174: end
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