Sequel Playground

README.md

ruby migrate.rb create ruby migrate.rb drop

$ irb

require_relative 'sequel'

user = User.first

user.send_welcome_email

user.notifications

migrate.rb

require 'sequel'

DB = Sequel.connect('postgres://postgres@localhost:5432/graveyard')
DB.extension :pg_enum

def drop_tables
  [:users, :comments, :posts, :notifications].each do |table|
    puts "Dropping table #{table}"
    DB.drop_table table if DB.table_exists?(table)
  end
end

def create_tables
  unless DB.table_exists?(:users)
    puts 'Creating users'

    DB.create_table :users do
      primary_key :id
      String :first_name, null: false
      String :last_name, null: false
    end
  end

  unless DB.table_exists?(:comments)
    puts 'Creating comments'

    DB.create_table :comments do
      primary_key :id
      foreign_key :user_id, null: false
      foreign_key :post_id, null: false
      String :text, null: false
    end
  end

  unless DB.table_exists?(:posts)
    puts 'Creating posts'

    DB.create_table :posts do
      primary_key :id
      foreign_key :user_id, null: false
      String :title, null: false
      String :body, null: false
    end
  end

  unless DB.table_exists?(:notifications)
    puts 'Creating notifications'
    DB.drop_enum(:type)
    DB.create_enum(:type, %w[password_reset rent_payment welcome_email])

    DB.create_table :notifications do
      primary_key :id
      foreign_key :user_id
      type :type
    end
  end
end

drop_tables if ARGV[0] == 'drop'
create_tables if ARGV[0] == 'create'

sequel.rb

require 'sequel'

DATABASE_NAME = 'sequel_playground'
DB = Sequel.connect("postgres://postgres@localhost:5432/#{DATABASE_NAME}")

class User < Sequel::Model
  one_to_many :comments
  one_to_many :posts
  one_to_many :notifications

  def send_welcome_email
    return if received_notification?(:welcome)
    create_notification('welcome')
    puts 'Welcome to the app!'
  end

  def rent_reminder
    return if received_notification?(:rent_reminder)
    create_notification('rent_reminder')
    puts 'Time to pay your rent!'
  end

  def password_reset
    create_notification('password_reset')
    puts 'Someone has requested a password reset'
  end

  def received_notification?(type)
    self.reload.notifications.any? do |notification|
      notification.type == Notification::TYPES[type.to_sym]
    end
  end

  def create_notification(type)
    Notification.create(user_id: self.id, type: type.to_s)
  end
end

class Post < Sequel::Model
  many_to_one :user
  one_to_many :comments
end

class Comment < Sequel::Model
  many_to_one :post
  many_to_one :user
end

class Notification < Sequel::Model
  one_to_one :user

  TYPES = {
    welcome: 'welcome',
    rent_reminder: 'rent_reminder',
    password_reset: 'password_reset'
  }
end

jane = User.create(
  first_name: 'Jane',
  last_name: 'Doe'
)

john = User.create(
  first_name: 'John',
  last_name: 'Brownstein'
)

Post.create(
  user_id: jane.id,
  title: 'How to Lose Weight',
  body: 'blah blah blah'
)

['this post sucks', 'great post!', 'lol'].each do |text|
  Comment.create(post_id: Post.first.id, text: text, user: john)
end