Cheatsheet for Ruby on Rails

basic.rb

##CRUD##

#create
Human.create

#read
Human.find(2)
Human.first
Human.last
human.name

#update
human.name("albert")
human.save

#delete
human.destroy

##Model##
class Human < ActiveRecord::base
  validates_presence_of :name
  validates_uniqueness_of :name
  validates :name, presence: true, uniqueness: true
  has_many: titles
  
end

class Title < ActiveRecord::Base
  belongs_to :human, foreign_key: :human_id, dependent: :destroy
end

controller.rb

# convention over configuration

# it will render show.html.erb
class ProductController < ApplicationController
  def show
    @product = Product.find(params[:id])
  end
end

# it will render status.html.erb
class ProductController < ApplicationController
  def show
    @product = Product.find(1)
    @products = Tweet.includes(:thumbnail).recent
    render action: "status"
  end
end

# params
?id=123&status[today]=good

#session hash
#flash hash
#params hash


#redirect_to 
before_action get_product, only: [:edit, :delete]

models.rb

#Scoping allows you to specify commonly-used queries 
#which can be referenced as method calls on the association objects or models. 

class Human < ActiveRecord::Base
  scope :smart, where(smart: true)
  scope :young, where("age < 25")
  scope :recent, where("create_at desc").limit(3)
end

#reading no need self, setting need self
class Human < ActiveRecord::Base
  before_save :become_smart
  
  def become_smart
    self.smart = true if age > 25
  end
  
end

#before after events
before_save
after_save
before_validation
after_validation
before_create
after_create
before_destroy
after_destroy

#has_one
humans = Human.includes(:pet).all

rails.sh

$rails new ProjectName

$rails generate / g

$rails console / c

$rails server / s

$rails dbconsole / db

$rails g scaffold Human name:string bio:text age:integer

string text boolean decimal float binary date time datetime

####

$rails db:migrate
$rails db:rollback
$rails db:schema:dump
$rails db:setup

$bundle install

routes.rb

# app/config/routes.rb
get '/new_product' => 'product#new'

get '/all' => 'products#index' as all_products
<%= link_to "all products", all_products_path %>

get '/all' => redirect('/products')

get '/filter_by/:category' => 'products:index'

#root

root to: "tweets#index"

root_path

ruby.rb

hash = { 'color' => 'green', 'number' => 5 } # string as keys
hash['color'] #=> 'green'

hash = { defcon: 3, action: true } # symbol as keys
hash['defcon'] #=> 3