Handle controller responses using Rails before_action

Using Rails before_action you can return an HTTP response before the actual controller action is invoked, in the example below, the create action. This allows you to clean up your controller code, so instead of having the create action running the code defined in setup_request and verify_request you can have a before action handle it for you.

The head method used below is an alias for responding only with the status given (as a symbol), headers, and an empty body.

class ExampleController < ApplicationController
  before_action :verify_request, :setup_request

  def create
    # handle action if before_action's have not rendered head

  def setup_request
    head :ok unless application_exists

  def verify_request
    head :unauthorized unless auth_token.present?