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.
Rendering Helpers
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
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 ActionController::Base to see other features you can bring into your metal controller.
- A
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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.
Parameters
- action - An action name
Returns
- proc - A rack application
Makes the controller a rack endpoint that points to the action in the given env’s action_dispatch.request.path_parameters key.
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
Alias for middleware_stack
Adds given middleware class and its args to bottom of middleware_stack
Basic implementations for content_type=, location=, and headers are provided to reduce the dependency on the RackDelegation module in Renderer and Redirector.
Delegates to the class’ controller_name