Rails 6: Questions and Answers

(in no particular order)

What are the Rails libraries?

Library	Description
Action Controller	actions
Action Dispatch	routing, params, session, cookies
Active Job	queuing, background jobs
Action Mailer	emails
Active Model	model interfaces
Action Pack	meta-package includes Controller and Dispatch
Active Record	ORM
Active Support	utilities, core extensions
Action View	templating, rendering

New in Rails 5 and 6

Library	Description
Action Cable	websockets since Rails 5
Action Mailbox	internal emails since Rails 6.0
Active Storage	cloud storage since Rails 5.2
Action Text	rich text editing since Rails 6.0

When creating a new Rails application, you have the option to skip:

• Cable

• Mailbox

• Mailer

• Record

• Storage

• Text

• Job?

Cable

Controller

Dispatch

Job

Mailbox

Mailer

Model

Pack

Record

Storage

Support

Text

View

Is it actually possible to use these libraries outside of Rails?

...

What are all those gems in the Gemfile?

Gem	Description
bcrypt
bootsnap
byebug
capybara
image_processing
jbuilder
listen
mysql2
pg
puma
rails
redis
sass-rails
selenium-webdriver
spring
spring-watcher-listen
sqlite3
turbolinks
tzinfo-data
web-console
webdrivers
webpacker

What is Bootsnap, and how does it work?

...

What is Listen, and how does it work?

...

What is Puma, and how does it work?

...

What is Spring, and how does it work?

...

What is Sprockets, and how does it work?

...

What is Turbolinks, and how does it work?

...

Why is there a bin folder, and what is it for?

...

Why is there a vendor folder, and what is it for?

...

What's the difference between all the assets folders?

app/assets

app/javascript

lib/assets

public/assets

How does the asset tree work?

app/assets/config/manifest.js

Why is the config/manifest.js file in app/assets and not config?

Sprockets 4 moves the configuration from config/application.rb to app/assets/config/manifest.js.

Previously, config/application.rb contained:

config.assets.precompile += []

Now app/assets/config/manifest.js contains:

//= link_tree ../images
//= link_directory ../stylesheets .css

What are concerns?

...

If global variables are "bad", what about global helpers?

app/helpers/application_helper.rb

How do credentials/secrets work?

config/credentials.yml.enc

config/master.key

tmp/development_secret.txt

.env

EDITOR="vim --wait" rails credentials:edit

credentials since Rails 5.2

What is @rails/ujs, and how do you use it?

...

How do the meta tags work?

csrf_meta_tags

csp_meta_tags

How does the stylesheet media option work?

media: 'all'

Is there a difference between dependencies and devDependencies?

...