Represents an HTTP response generated by a controller action. One can use an ActionDispatch::Response object to retrieve the current state of the response, or customize the response. An Response object can either represent a "real" HTTP response (i.e. one that is meant to be sent back to the web browser) or a test response (i.e. one that is generated from integration tests). See CgiResponse and TestResponse, respectively.

Response is mostly a Ruby on Rails framework implement detail, and should never be used directly in controllers. Controllers should use the methods defined in ActionController::Base instead. For example, if you want to set the HTTP response‘s content MIME type, then use ActionControllerBase#headers instead of Response#headers.

Nevertheless, integration tests may want to inspect controller responses in more detail, and that‘s when Response can be useful for application developers. Integration test methods such as ActionDispatch::Integration::Session#get and ActionDispatch::Integration::Session#post return objects of type TestResponse (which are of course also of type Response).

For example, the following demo integration "test" prints the body of the controller response to the console:

 class DemoControllerTest < ActionDispatch::IntegrationTest
   def test_print_root_path_to_console
     get('/')
     puts @response.body
   end
 end