[Srijan Wednesday Webinar] Rails 5: What's in It for Me?

Rails 5
What’s in it for
me?
@_cha1tanya
@BigBinary
@Srijan

Rails.5.started
_on?
Nov, 2014

Ruby 2.2.2+
Rails 5 will require that your apps runs on
Ruby 2.2.2 or latest.

Chance to cleanup
Rails internals

Keyword arguments
Rails code can use keyword arguments
internally as now it only supports Ruby 2.2.2 +

Action Cable
DHH talking about Action Cable
https://www.youtube.com/watch?
v=n0WUjGkDFS0

Full Stack
It has both Ruby side as well as JavaScript
side.

Seamless
integration with
other parts

module ApplicationCable
class Connection < ActionCable::Connection::Base
identified_by :current_user
def connect
self.current_user = find_verified_user
end
protected
def find_verified_user
id = cookies.signed[:user_id]
if current_user = User.find_by(id: id)
current_user
else
reject_unauthorized_connection
end
end
end
end

Ruby side
Initially it was started with hard dependency on event
machine.
It was later dropped in
https://github.com/rails/rails/commit/74497eabd52f2f9f8c
383808b11286283046c2b2.
Now Action Cable does not have hard dependency on
Event machine

These are the 3 dependencies of Action
Cable on Ruby side:
websocket-driver
nio4r
concurrent-ruby

Inline
Async
Good for development and test mode.

Evented Redis
Non-Evented Redis
Postgresql
For production mode.

Rendering a
template
outside of
controller

ActionController::Renderer.render

Twitter API
Github API
Supplementary APIs where apps are still
traditional web apps

Proliferation of
client side
frameworks

Rails as a Back
End
Which results into using Rails only as back
end app.

JBuilder
ActiveModel::Serial
izer
These can be used with API only apps to
generate JSON

Create new Rails API only app
with
rails new api_app --api

Convert existing app to API only app
config.api_only = true

Puma
Puma is default web server now

config/puma.rb
Newly created Rails 5 apps will come with a
config/puma.rb by default.

In Rails 5, just use `rails`
rails db:migrate

One `rails`
command to bind
them all!

rails restart
Ability to restart Rails app in development.
https://github.com/rails/rails/issues/18876

tmp/restart.txt
Similar to how passenger restarts app by touching
tmp/restart.txt

Caching in
development mode
In previous Rails versions, caching does not
work automatically in development. Now it
will work in Rails 5.

Toggles caching
in development

Filtering
routes
Ability to filter routes.

rails routes -c PostsController

Reloading in
development
Rails reloads all code in development when something
changes. For that it has to do a complete walkthrough
of all files.

Check something has
changed or not

Test Runner
Rails 5 has added Rspec like test runner
http://blog.bigbinary.com/2016/01/03/test-
runner-in-rails-5.html

Running a single test by line number
$ bin/rails test test/models/user_test.rb:27

$ bin/rails test test/models test/jobs

$ bin/rails t
Run options: --seed 51858
# Running:
.F
Failure:
PostsControllerTest#test_should_get_new:
Expected response to be a <success>, but was a <302>
redirect to <http://test.host/posts>
bin/rails test test/controllers/posts_controller_test.rb:15

$ bin/rails t -f
Run options: -f --seed 59599
# Running:
..F
Failure:
PostsControllerTest#test_should_get_new:
Expected response to be a <success>, but was a <302> redirect to
<http://test.host/posts>
bin/rails test test/controllers/posts_controller_test.rb:15
Interrupted. Exiting...
Finished in 0.179125s, 16.7481 runs/s, 22.3308 assertions/s.
3 runs, 4 assertions, 1 failures, 0 errors, 0 skips

See complete backtrace with -b switch
$ bin/rails t -b
Error:
PostsControllerTest#test_should_create_post:
NameError: undefined local variable or method `boom' for
#<PostsController:0x007fc53c4eb868>
/rails-5-test-runner-app/app/controllers/posts_controller.rb:29:in
`create'
/sources/rails/actionpack/lib/action_controller/metal/basic_implicit_render.rb
:4:in `send_action'
/sources/rails/actionpack/lib/abstract_controller/base.rb:183:in
`process_action'
/sources/rails/actionpack/lib/action_controller/metal/rendering.rb:30:in
`process_action'
/sources/rails/actionpack/lib/abstract_controller/callbacks.rb:20:in
`block in process_action'
/sources/rails/activesupport/lib/active_support/callbacks.rb:126:in `call'
.....
/sources/rails/activesupport/lib/active_support/testing/assertions.rb:71:in
`assert_difference'
/rails-5-test-runner-app/test/controllers/posts_controller_test.rb:19:in
`block in <class:PostsControllerTest>'

gem ‘action-controller_testing’

Controller tests
are integration
tests

def test_index
get :index
assert_response :success
end

Example of changed controller test.
def test_index
get posts_url
assert_response :success
end

ActionController::TestCase
In Rails 4.x this was the superclass for all controller
tests.

ActionDispatch::IntegrationTest
Now it is this one. Also a lot of effort has gone into
making these tests faster.

More focus on
integration
testing

def index
http_cache_forever do
render ‘index’
end
end

Use it with
caution!
It will literally set the cache control headers
for ‘forever’. Make sure that you are using it
with static content only.

@users = User.where(city: 'Pune')

No record is deleted.
No record is added.

ActiveRecord::Relation#cache_key

@users.cache_key
=> "users/query-67ed32b36805123"

cache(@users) do
………
end

Limitations
Doesn’t work well with limits and groups.

# index.html.erb
<%= render partial: 'todo',
collection: @todos %>
# _todo.html.erb
<% cache todo do %>
<%= todo.name %>
<% end %>

Just pass `cached: true` and Rails will fetch all caches
at once.
# index.html.erb
<%= render partial: 'todo',
collection: @todos,
cached: true %>
# _todo.html.erb
<% cache todo do %>
<%= todo.name %>
<% end %>

ApplicationReco
rd
ApplicationRecord is a new superclass for all app models,
analogous to app controllers subclassing ApplicationController
instead of ActionController::Base. This gives apps a single spot to
configure app-wide model behavior

class Post < ActiveRecord::Base
end

class Post < ApplicationRecord
end

#or
Added the #or method on ActiveRecord::Relation,
allowing use of the OR operator to combine WHERE or
HAVING clauses

Post.where('id = 1').or(Post.where('id = 2'))
# => SELECT * FROM posts WHERE (id = 1) OR
(id = 2)

has_secure_toke
n
Added ActiveRecord::SecureToken in order to
encapsulate generation of unique tokens for
attributes in a model using SecureRandom
https://github.com/rails/rails/pull/18217

class User < ApplicationRecord
has_secure_token
end

>> user = User.new
>> user.save
=> true
>> user.token
=> 'qjCbex522DfVEVd5ysUWppWQ'

>> user = User.first
=> <User id: 11, name: 'John', email: 'john@example.com',
token: "jRMcN645BQyDr67yHR3qjsJF",
token: "qjCbex522DfVEVd5ysUWppWQ">
>> user.token
=> "qjCbex522DfVEVd5ysUWppWQ"
>> user.regenerate_token
=> true
>> user.token
=> "tYYVjnCEd1LAXvmLCyyQFzbm"

For eg. in Rails 4.x
t.timestamps null: false

But in Rails 5, there is no `null: false` still it adds
`NULL` constraint when the migration is run in Rails 5.
t.timestamps # Rails 5

ActiveRecord::Migration
[5.0]
Superclass of migrations in Rails 5. Tells Rails for which
version this migration was generated.

Time.current
=> Fri, 12 Feb 2016 08:53:31 UTC +00:00
Time.current.next_day
=> Sat, 13 Feb 2016 08:53:31 UTC +00:00
Time.current.prev_day
=> Thu, 11 Feb 2016 08:53:31 UTC +00:00

Time.current
=> Fri, 12 Feb 2016 09:15:10 UTC +00:00
Time.current.next_week
=> Mon, 15 Feb 2016 00:00:00 UTC +00:00
Time.current.next_week(same_time: true)
=> Mon, 15 Feb 2016 09:15:20 UTC +00:00

Time.current
=> Fri, 12 Feb 2016 09:47:40 UTC +00:00
Time.current.on_weekend?
=> false
Time.current.tomorrow
=> Sat, 13 Feb 2016 09:48:47 UTC +00:00
Time.current.tomorrow.on_weekend?
=> tru

Time.current
=> Fri, 12 Feb 2016 09:47:40 UTC +00:00
Time.current.on_weekday?
=> true
Time.current.tomorrow
=> Sat, 13 Feb 2016 09:48:47 UTC +00:00
Time.current.tomorrow.on_weekday?
=> false

Time.current
=> Fri, 12 Feb 2016 09:47:40 UTC +00:00
Time.current.next_weekday
=> Mon, 15 Feb 2016 09:55:14 UTC +00:00
Time.current.prev_weekday
=> Thu, 11 Feb 2016 09:55:33 UTC +00:00

users = [{id: 1, name: 'Max'},
{id: 2, name: 'Mark'},
{id: 3, name: 'Jen'}]
users.pluck(:name)
=> ["Max", "Mark", "Jen"]

users = [{id: 1, name: 'Max'},
{id: 2, name: 'Mark'},
{id: 3, name: 'Jen'}]
users.pluck(:id, :name)
=> [[1, "Max"], [2, "Mark"],
[3, "Jen"]]

Improvement to
Active Record’s
pluck

# In Rails 4.x
users = User.all
SELECT `users`.* FROM `users`
# SELECT "users"."id", "users"."name"
FROM “users"
=> [[1, "Max"], [2, "Mark"],
[3, "George"]]

# In Rails 5
users = User.all
SELECT `users`.* FROM `users`
=> [[1, "Max"], [2, "Mark"],
[3, "George"]]

vehicles = ['Car', 'Bike', 'Truck',
'Bus']
vehicles.without("Car", "Bike")
=> ["Truck", "Bus"]

vehicles = {car: 'Hyundai', bike:
'Honda', bus: 'Mercedes', truck:
'Tata'}
vehicles.without(:bike, :bus)
=> {:car=>"Hyundai", :truck=>"Tata"}

Halting
callback chain
Changed the way in which callback chains can be halted. The
preferred method to halt a callback chain from now on is to
explicitly throw(:abort).
https://github.com/rails/rails/pull/17227

return false from
one of the `before`
callbacks

Rails 5 no longer
has this side
effect!

throw(:abort)
Explicitly throw(:abort) to stop it.

While upgrading, it
will still halt
For older apps getting upgraded to Rails 5, the
callback will still halt with returning false, as this is a
breaking change.

ActiveSupport.halt_callback_chains_on_return_false
Once you are ready, toggle this flag and it will use new behaviour of throw.

https://github.com/rails/rails/pul
l/21057
l/18643
l/21411
l/21155
l/20946

If you are new to Rails, check out the Rails Doctrine to
understand the philosophy behind Rails.
rubyonrails.org/doctr
ine/

blog.bigbinary.com/categori
es/Rails%205

Thank you!
@_cha1tanya
@BigBinary
@Srijan

[Srijan Wednesday Webinar] Rails 5: What's in It for Me?

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