Rails 4: before_filter vs. before_action

In rails >4.0.0 generators creates CRUD operations with before_action not before_filter. It seems to do the same thing. So what's the difference between these two?

As we can see in ActionController::Base, before_action is just a new syntax for before_filter.

However the before_filter syntax is deprecated in Rails 5.0 and will be removed in Rails 5.1

It is just syntax difference, in rails app there is CRUD, and seven actions basically by name index, new, create, show, update, edit, destroy.

Rails 4 make it developer friendly to change syntax before filter to before action.

before_action call method before the actions which we declare, like

before_action :set_event, only: [:show, :update, :destroy, :edit]

set_event is a method which will call always before show, update, edit and destroy.

It is just a name change. before_action is more specific, because it gets executed before an action.

before_filter/before_action: means anything to be executed before any action executes.

Both are same. they are just alias for each other as their behavior is same.

use only before_action with rspec-rails, capybara as before_filter will misbehave to give surprises during testing

class TodosController < ApplicationController
  before_filter :authenticate

  def index
    @todos = Todo.all
  end
  ## Rest of the code follows
end

before_filter

feature 'User creates todo' do
  scenario 'successfully' do
    sign_in
    click_on 'Add Todo'
    fill_in 'Title', with: "Buy Milk"
    click_on 'Submit'

    expect(page).to have_css '.todos li', text: "Buy Milk"
  end
end

the expected failure is

NoMethodError:
       undefined method `authenticate' for #<TodosController:0x0000558b68573f48>

but before_filter gives...

ActionView::Template::Error:
       undefined method `each' for nil:NilClass

That is, somehow the hook runs without error and but the controller goes to view with a @todos uninitialized Better save time, use non deprecated codes...

To figure out what is the difference between before_action and before_filter, we should understand the difference between action and filter.

An action is a method of a controller to which you can route to. For example, your user creation page might be routed to UsersController#new - new is the action in this route.

Filters run in respect to controller actions - before, after or around them. These methods can halt the action processing by redirecting or set up common data to every action in the controller.

> Rails 4 –> _action > > Rails 3 –> _filter