Exploring ActionController::Responder

Anything that responds to call, accepting three arguments, can be a responder. The three arguments given to call are the current controller, the resource (or a nested resource or an array of resources), and a hash of options. All the options given to respond_with are forwarded to the responder as the third argument.

ActionController::Responder implements the call method in a single line of code, as we can see in the Rails source code:

rails/actionpack/lib/action_controller/metal/responder.rb
 
def​ self.call(*args)
 
new(*args).respond
 
end

The call method forwards these three arguments to the ActionController::Responder initialization and then calls respond:

rails/actionpack/lib/action_controller/metal/responder.rb ...

Get Crafting Rails 4 Applications, 2nd Edition now with O’Reilly online learning.

O’Reilly members experience live online training, plus books, videos, and digital content from 200+ publishers.