Rails Tutorial

March 29, 2023

Rails Book Tutorial

Tools

Cloud 9. Visit https://console.aws.amazon.com/ and search for cloud 9 for online environment
Heroku. Login:

Ruby on Rails

echo "gem: --no-document" >> ~/.gemrc save time by skipping downloading docs gem install rails -v 7.0.4 install rails, particular version gem install bundler -v 2.3.14 install bundler, particular version source <(curl -sL https://cdn.learnenough.com/resize) resize cloud9 vm rails _7.0.4_ new hello_app --skip-bundle create app but allow for gemfile modifications. You can edit the gemfile versions before continuing. bundle _2.3.14_ install run install rails server or rails s start the server.

For cloud9 make sure to edit the development environment config and add:

  config.hosts.clear
  config.web_console.whitelisted_ips = [<your_ip>]

git config --global init.defaultBranch main set default branch name git config --global credential.helper "cache --timeout=86400" set login cache time for easy use in cloud9 git branch -M main set the main branch

building without production gems

bundle _2.3.14_ config set --local without 'production'
bundle _2.3.14_ install
bundle _2.3.14_ lock --add-platform x86_64-linux
source <(curl -sL https://cdn.learnenough.com/heroku_install) # install heroku

heroku login -i login on the cloud app git push heroku main push branch up to heroku heroku logs show logs herokue app:info get app info

rails generate scaffold User name:string email:string scaffold users rails db:migrate apply db changes heroku run rails db:migrate migrate db in heroku heroku logs --tail watch logs rails destroy controller StaticPages home help remove a controller rails destroy model User remove a user rails db:rollback rollback migration

ERB

<% ... %> executes code <%= ... %> executes and inserts <%= yield %> inserts page contents

test_helper.rb

require "minitest/reporters"
Minitest::Reporters.use!

bundle _2.3.14_ exec guard init add guard to watch tests bundle _2.3.14_ exec guard run guard

For Cloud9, edit ~/.irbrc:

IRB.conf[:PROMPT_MODE] = :SIMPLE
IRB.conf[:AUTO_INPUT_MODE] = false

rails c open IRB

attr_accessor :name, :email adds getter and setter to the class @name is an instance var

https://en.wikipedia.org/wiki/Active_record_pattern https://sqlitebrowser.org/

brew install --cask db-browser-for-sqlite install sqlite browser

rails console --sandbox load console in a sandbox, any modficaitons are rolled back on exit

DB migrations

The rails way is to generate a migraion: rails generate migration add_index_to_users_email

self.email = email.downcase is ok, email = email.downcase is not. Assignment requires self, the value does not

heroku run rails db:migrate production db migrate heroku run rails console --sandbox run the rails console on production heroku

<%= debug(params) if Rails.env.development? %> debug params rails server --environment production run production rails db:migrate RAILS_ENV=production migrate production

https://stackoverflow.com/questions/941594/understanding-the-rails-authenticity-token

assert_no_difference use for db testing, more idiomatic

concerns are a way of mixing in functionality.

https://www.akshaykhot.com/how-rails-concerns-work-and-how-to-use-them/

session fixation use reset_session to avoid

@current_user = @current_user || User.find_by(id: session[:user_id]) and @current_user ||= User.find_by(id: session[:user_id]) are the same, the latter is more idiomatic

rails importmap:install turbo:install stimulus:install usually run automatically but we skipped with --skip-bundle

user&.authenticate safe navigation operator

unless @user == current_user is the same as unless current_user?(@user), the latter is more idiomatic and expressive

rails db:migrate:reset
rails db:seed

user.microposts.build(arg) # more idiomatic, through relationship
user.microposts.find_by(id: 1)

build is an alias for new

default_scope -> { order(created_at: :desc) } sort desending on create date -> is stabby lambda syntax, takes a block and returns a proc

https://github.com/faker-ruby/faker

private methods can be called from derived classes

https://guides.rubyonrails.org/active_record_querying.html

cloud 9 memory/cpu issues

https://docs.aws.amazon.com/cloud9/latest/user-guide/troubleshooting.html#troubleshooting-ide-low-memory

sudo swapon --show
sudo swapoff -a # if running
sudo fallocate --length 512MB /var/swapfile && sudo chmod 600 /var/swapfile && sudo mkswap /var/swapfile && echo '/var/swapfile swap swap defaults 0 0' | sudo tee -a /etc/fstab > /dev/null
sudo swapon /var/swapfile

image upload

rails active_storage:install
rails db:migrate

sudo apt-get -y install imagemagick

amazon:
  service: S3
  access_key_id:     <%= ENV['AWS_ACCESS_KEY_ID'] %>
  secret_access_key: <%= ENV['AWS_SECRET_ACCESS_KEY'] %>
  region:            <%= ENV['AWS_REGION'] %>
  bucket:            <%= ENV['AWS_BUCKET'] %>

many-to-many relationships are complex

naive implementation

through relationships are likely better

model folled through active relationships

    add_index :relationships, :follower_id
    add_index :relationships, :followed_id
    add_index :relationships, [:follower_id, :followed_id], unique: true

would allow a unique combo or indiviual (async) relationships

user.active_relationships.build(followed_id: ...) build relationships

By default, Rails expects a foreign key of the form <class>_id

has_many :followeds, through: :active_relationships rails default associations, overridden by has_many :following, through: :active_relationships, source: :followed to make more sense

https://guides.rubyonrails.org/routing.html

https://hotwired.dev/

https://www.learnenough.com/action-cable

&:to_s shorthand for { |i| i.to_s }, use with map for example

http://railscasts.com/episodes/274-remember-me-reset-password

As a general rule, if a method doesn’t need an instance of an object, it should be a class method

Class methods

def self.digest(string)
end

def User.digest(string)
end

class << self
def digest(string)
end
end

if (user_id = session[:user_id]) if session id exists, ,assing to user_id. () is a convention to denote assignment

pushing to heroku with maintenence mode

heroku maintenance:on
git push heroku
heroku run rails db:migrate
heroku maintenance:off

before_create :create_activation_digest method reference, calls the method create_activation_digest

# mutliple db calls
# update_attribute(:activated,    true)
# update_attribute(:activated_at, Time.zone.now)

# single db call
update_columns(activated: true, activated_at: Time.zone.now)

heroku addons:create sendgrid:starter sendgrid addon grep heroku .git/config show config

https://docs.sendgrid.com/ui/sending-email/sender-verification