Plug pipeline in controllers

In many web frameworks, there's a way to filter and intercept requests that are dispatched to a controller’s action and perform specific checks on them. For example, Rails has filters, specifically the before_action hooks, which are called before the request reaches the controller’s action. These checks can log a request, perform a redirect, or even halt the request-response cycle. A well-known usage of these filters is to ensure that an incoming request is authenticated:

Figure 5.1 – Plug pipeline in Phoenix

Here’s how authentication using filters looks in a Rails controller:

class PageController < ApplicationController
  before_action :ensure_authenticated!
  before_action :ensure_authorized!, only: [:index]
  def index
    # index action related code
  end
  def show
    # show action related code...